LNK3205D-TL

LNK3202/3204-6 LinkSwitch-TN2 Family Highly Energy Efficient Off-line Switcher IC with Integrated System Level Protection for Low Component-Count Power Supplies Product Highlights Highest Performance and Design Flexibility ? Supports buck, buck-boost and flyback topologies ? Low component-count buck converter FB BP/M ? Excellent load and line regulation ? Selectable device current limit D S + ? High current limit extends peak power and maximizes continuous LinkSwitch-TN2 Wide Range DC output power High-Voltage Output DC Input ? Low current limit allows the use of lowest-cost surface mount buck chokes ? 66 kHz operation with accurate current limit PI-7841-041816 ? Allows the use of low-cost off-the-shelf inductors Figure 1. Typical Buck Converter Application (See Application Examples ? Reduces size and cost of magnetics and output capacitor Section for Other Circuit Configurations). ? Frequency jittering reduces EMI lfi ter complexity ? Pin-out simpliefi s PCB heat sinking Enhanced Safety and Reliability Features ? Auto-restart for short-circuit and open loop faults ? Limits power delivery to 3% of maximum during a fault ? Output overvoltage protection (OVP) ? Line input overvoltage protection (OVL) ? Hysteretic over-temperature protection (OTP) ? Extended creepage between DRAIN pin and all other pins improves Figure 2. Package Options. P: PDIP-8C, G: SMD-8C, D: SO-8C. field reliability ? 725 V MOSFET rating for excellent surge withstand ? Extremely low component count enhances reliability 1 ? Allows single-sided PCB and full SMD manufacturability Output Current Table ? 230 VAC ?15% 85-265 VAC EcoSmart ? Extremely Energy Efficient 4 Product 2 3 2 3 ? Standby supply current <100 ?A MDCM CCM MDCM CCM ? On/Off control provides constant efcfi iency over a wide load range LNK3202P/G/D 63 mA 80 mA 63 mA 80 mA ? Easily meets all global energy efcfi iency regulations LNK3204P/G/D 120 mA 170 mA 120 mA 170 mA ? No-load <30 mW in high-side buck converters with external bias ? No-load <10 mW in yfl back converters with external bias LNK3205P/G/D 175 mA 270 mA 175 mA 270 mA LNK3206P/G/D 225 mA 360 mA 225 mA 360 mA Applications ? Appliances Table 1. Output Current Table. ? Metering Notes: ? Smart LED drivers and industrial controls 1. Typical output current in a non-isolated buck converter with devices operating ? IOT, home and building automation at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. See Key Description Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. The LinkSwitch?-TN2 family of ICs for non-isolated off-line power 2. Mostly discontinuous conduction mode. supplies provide dramatically improved performance compared to 3. Continuous conduction mode. 4. Packages: P: PDIP-8C, G: SMD-8C, D: SO-8C. traditional linear or cap-dropper solutions. Designs using the highly integrated LinkSwitch-TN2 ICs are more flexible and feature increased efficiency, comprehensive system level protection and higher reliability. The device family supports buck, buck-boost and flyback converter BYPASS pin capacitor value. The high current limit level provides topologies. Each device incorporates a 725 V power MOSFET, oscillator, maximum continuous output current while the low level permits using On/Off control for highest efficiency at light load, a high-voltage very low cost and small surface mount inductors. A full suite of switched current source for self-biasing, frequency jittering, fast protection features enable safe and reliable power supplies protecting (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output the device and the system against input and output overvoltage faults, and input overvoltage protection circuitry onto a monolithic IC. device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. LinkSwitch-TN2 ICs consume very little current in standby resulting in power supply designs that meet all no-load and standby specifications The device family is available in three different packages: PDIP-8C, worldwide. MOSFET current limit modes can be selected through the SO-8C, and SMD-8C. www.power.com January 2017 This Product is Covered by Patents and/or Pending Patent Applications. +LNK3202/3204-6 LinkSwitch-TN2 Family Highly Energy Efficient Off-line Switcher IC with Integrated System Level Protection for Low Component-Count Power Supplies Product Highlights Highest Performance and Design Flexibility ? Supports buck, buck-boost and flyback topologies ? Low component-count buck converter FB BP/M ? Excellent load and line regulation ? Selectable device current limit D S + ? High current limit extends peak power and maximizes continuous LinkSwitch-TN2 Wide Range DC output power High-Voltage Output DC Input ? Low current limit allows the use of lowest-cost surface mount buck chokes ? 66 kHz operation with accurate current limit PI-7841-041816 ? Allows the use of low-cost off-the-shelf inductors Figure 1. Typical Buck Converter Application (See Application Examples ? Reduces size and cost of magnetics and output capacitor Section for Other Circuit Configurations). ? Frequency jittering reduces EMI lfi ter complexity ? Pin-out simpliefi s PCB heat sinking Enhanced Safety and Reliability Features ? Auto-restart for short-circuit and open loop faults ? Limits power delivery to 3% of maximum during a fault ? Output overvoltage protection (OVP) ? Line input overvoltage protection (OVL) ? Hysteretic over-temperature protection (OTP) ? Extended creepage between DRAIN pin and all other pins improves Figure 2. Package Options. P: PDIP-8C, G: SMD-8C, D: SO-8C. field reliability ? 725 V MOSFET rating for excellent surge withstand ? Extremely low component count enhances reliability 1 ? Allows single-sided PCB and full SMD manufacturability Output Current Table ? 230 VAC ?15% 85-265 VAC EcoSmart ? Extremely Energy Efficient 4 Product 2 3 2 3 ? Standby supply current <100 ?A MDCM CCM MDCM CCM ? On/Off control provides constant efcfi iency over a wide load range LNK3202P/G/D 63 mA 80 mA 63 mA 80 mA ? Easily meets all global energy efcfi iency regulations LNK3204P/G/D 120 mA 170 mA 120 mA 170 mA ? No-load <30 mW in high-side buck converters with external bias ? No-load <10 mW in yfl back converters with external bias LNK3205P/G/D 175 mA 270 mA 175 mA 270 mA LNK3206P/G/D 225 mA 360 mA 225 mA 360 mA Applications ? Appliances Table 1. Output Current Table. ? Metering Notes: ? Smart LED drivers and industrial controls 1. Typical output current in a non-isolated buck converter with devices operating ? IOT, home and building automation at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. See Key Description Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. The LinkSwitch?-TN2 family of ICs for non-isolated off-line power 2. Mostly discontinuous conduction mode. supplies provide dramatically improved performance compared to 3. Continuous conduction mode. 4. Packages: P: PDIP-8C, G: SMD-8C, D: SO-8C. traditional linear or cap-dropper solutions. Designs using the highly integrated LinkSwitch-TN2 ICs are more flexible and feature increased efficiency, comprehensive system level protection and higher reliability. The device family supports buck, buck-boost and flyback converter BYPASS pin capacitor value. The high current limit level provides topologies. Each device incorporates a 725 V power MOSFET, oscillator, maximum continuous output current while the low level permits using On/Off control for highest efficiency at light load, a high-voltage very low cost and small surface mount inductors. A full suite of switched current source for self-biasing, frequency jittering, fast protection features enable safe and reliable power supplies protecting (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output the device and the system against input and output overvoltage faults, and input overvoltage protection circuitry onto a monolithic IC. device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. LinkSwitch-TN2 ICs consume very little current in standby resulting in power supply designs that meet all no-load and standby specifications The device family is available in three different packages: PDIP-8C, worldwide. MOSFET current limit modes can be selected through the SO-8C, and SMD-8C. www.power.com January 2017 This Product is Covered by Patents and/or Pending Patent Applications. +LNK3202/3204-6 BYPASS DRAIN (BP/M) (D) REGULATOR 5.0 V FAULT I I FBSD FB PRESENT BYPASS PIN CAPACITOR 5.2 V DETECT AUTO-RESTART BYPASS PIN COUNTER UNDERVOLTAGE OVL + CURRENT LIMIT CLOCK COMPARATOR 5.0 V - RESET 4.5 V V I LIMIT JITTER CLOCK THERMAL SHUTDOWN DC MAX OSCILLATOR S Q FEEDBACK (FB) R Q 2.0 V -V T LEADING EDGE BLANKING OVP DETECT SOURCE (S) PI-7879-100416 Figure 3. Functional Block Diagram. Pin Functional Description SOURCE (S) Pin: This pin is the power MOSFET source connection. It is also the DRAIN (D) Pin: ground reference for the BYPASS and FEEDBACK pins. Power MOSFET drain connection. Provides internal operating current for both start-up and steady-state operation. BYPASS (BP/M) Pin: This pin has multiple functions: P Package (DIP-8C) ? It is the connection point for an external bypass capacitor for the G Package (SMD-8C) D Package (SO-8C) internally generated 5.0 V supply. ? It is a mode selector for the current limit value, depending on the value of the capacitance added. Use of a 0.1 ?F capacitor results 1 8 in the standard current limit value. Use of a 1 ?F capacitor results BP/M 1 8 S BP/M S in the current limit being reduced, allowing design with lowest cost 2 7 2 7 FB S FB S surface mount buck chokes. ? It provides a shutdown function. When the current into the BYPASS 6 S 6 S pin exceeds I for a time equal to 2 to 3 cycles of the internal BPSD 4 5 oscilator (f ), the device enters auto-restart. This can be used to D S OSC 4 5 D S provide an output overvoltage protection function with external circuitry. FEEDBACK (FB) Pin: During normal operation, switching of the power MOSFET is con- PI-7842-022416 trolled by the FEEDBACK pin. MOSFET switching is terminated when a current greater than I (49 ?A) is delivered into this pin. Line Figure 4. Pin Configuration. FB overvoltage protection is detected when a current greater than I FBSD (670 ?A) is delivered into this pin for 2 consecutive switching cycles. 2 Rev. F 01/17 www.power.com - +LNK3202/3204-6 LinkSwitch-TN2 Family Highly Energy Efficient Off-line Switcher IC with Integrated System Level Protection for Low Component-Count Power Supplies Product Highlights Highest Performance and Design Flexibility ? Supports buck, buck-boost and flyback topologies ? Low component-count buck converter FB BP/M ? Excellent load and line regulation ? Selectable device current limit D S + ? High current limit extends peak power and maximizes continuous LinkSwitch-TN2 Wide Range DC output power High-Voltage Output DC Input ? Low current limit allows the use of lowest-cost surface mount buck chokes ? 66 kHz operation with accurate current limit PI-7841-041816 ? Allows the use of low-cost off-the-shelf inductors Figure 1. Typical Buck Converter Application (See Application Examples ? Reduces size and cost of magnetics and output capacitor Section for Other Circuit Configurations). ? Frequency jittering reduces EMI lfi ter complexity ? Pin-out simpliefi s PCB heat sinking Enhanced Safety and Reliability Features ? Auto-restart for short-circuit and open loop faults ? Limits power delivery to 3% of maximum during a fault ? Output overvoltage protection (OVP) ? Line input overvoltage protection (OVL) ? Hysteretic over-temperature protection (OTP) ? Extended creepage between DRAIN pin and all other pins improves Figure 2. Package Options. P: PDIP-8C, G: SMD-8C, D: SO-8C. field reliability ? 725 V MOSFET rating for excellent surge withstand ? Extremely low component count enhances reliability 1 ? Allows single-sided PCB and full SMD manufacturability Output Current Table ? 230 VAC ?15% 85-265 VAC EcoSmart ? Extremely Energy Efficient 4 Product 2 3 2 3 ? Standby supply current <100 ?A MDCM CCM MDCM CCM ? On/Off control provides constant efcfi iency over a wide load range LNK3202P/G/D 63 mA 80 mA 63 mA 80 mA ? Easily meets all global energy efcfi iency regulations LNK3204P/G/D 120 mA 170 mA 120 mA 170 mA ? No-load <30 mW in high-side buck converters with external bias ? No-load <10 mW in yfl back converters with external bias LNK3205P/G/D 175 mA 270 mA 175 mA 270 mA LNK3206P/G/D 225 mA 360 mA 225 mA 360 mA Applications ? Appliances Table 1. Output Current Table. ? Metering Notes: ? Smart LED drivers and industrial controls 1. Typical output current in a non-isolated buck converter with devices operating ? IOT, home and building automation at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. See Key Description Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. The LinkSwitch?-TN2 family of ICs for non-isolated off-line power 2. Mostly discontinuous conduction mode. supplies provide dramatically improved performance compared to 3. Continuous conduction mode. 4. Packages: P: PDIP-8C, G: SMD-8C, D: SO-8C. traditional linear or cap-dropper solutions. Designs using the highly integrated LinkSwitch-TN2 ICs are more flexible and feature increased efficiency, comprehensive system level protection and higher reliability. The device family supports buck, buck-boost and flyback converter BYPASS pin capacitor value. The high current limit level provides topologies. Each device incorporates a 725 V power MOSFET, oscillator, maximum continuous output current while the low level permits using On/Off control for highest efficiency at light load, a high-voltage very low cost and small surface mount inductors. A full suite of switched current source for self-biasing, frequency jittering, fast protection features enable safe and reliable power supplies protecting (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output the device and the system against input and output overvoltage faults, and input overvoltage protection circuitry onto a monolithic IC. device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. LinkSwitch-TN2 ICs consume very little current in standby resulting in power supply designs that meet all no-load and standby specifications The device family is available in three different packages: PDIP-8C, worldwide. MOSFET current limit modes can be selected through the SO-8C, and SMD-8C. www.power.com January 2017 This Product is Covered by Patents and/or Pending Patent Applications. +LNK3202/3204-6 LinkSwitch-TN2 Family Highly Energy Efficient Off-line Switcher IC with Integrated System Level Protection for Low Component-Count Power Supplies Product Highlights Highest Performance and Design Flexibility ? Supports buck, buck-boost and flyback topologies ? Low component-count buck converter FB BP/M ? Excellent load and line regulation ? Selectable device current limit D S + ? High current limit extends peak power and maximizes continuous LinkSwitch-TN2 Wide Range DC output power High-Voltage Output DC Input ? Low current limit allows the use of lowest-cost surface mount buck chokes ? 66 kHz operation with accurate current limit PI-7841-041816 ? Allows the use of low-cost off-the-shelf inductors Figure 1. Typical Buck Converter Application (See Application Examples ? Reduces size and cost of magnetics and output capacitor Section for Other Circuit Configurations). ? Frequency jittering reduces EMI lfi ter complexity ? Pin-out simpliefi s PCB heat sinking Enhanced Safety and Reliability Features ? Auto-restart for short-circuit and open loop faults ? Limits power delivery to 3% of maximum during a fault ? Output overvoltage protection (OVP) ? Line input overvoltage protection (OVL) ? Hysteretic over-temperature protection (OTP) ? Extended creepage between DRAIN pin and all other pins improves Figure 2. Package Options. P: PDIP-8C, G: SMD-8C, D: SO-8C. field reliability ? 725 V MOSFET rating for excellent surge withstand ? Extremely low component count enhances reliability 1 ? Allows single-sided PCB and full SMD manufacturability Output Current Table ? 230 VAC ?15% 85-265 VAC EcoSmart ? Extremely Energy Efficient 4 Product 2 3 2 3 ? Standby supply current <100 ?A MDCM CCM MDCM CCM ? On/Off control provides constant efcfi iency over a wide load range LNK3202P/G/D 63 mA 80 mA 63 mA 80 mA ? Easily meets all global energy efcfi iency regulations LNK3204P/G/D 120 mA 170 mA 120 mA 170 mA ? No-load <30 mW in high-side buck converters with external bias ? No-load <10 mW in yfl back converters with external bias LNK3205P/G/D 175 mA 270 mA 175 mA 270 mA LNK3206P/G/D 225 mA 360 mA 225 mA 360 mA Applications ? Appliances Table 1. Output Current Table. ? Metering Notes: ? Smart LED drivers and industrial controls 1. Typical output current in a non-isolated buck converter with devices operating ? IOT, home and building automation at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. See Key Description Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. The LinkSwitch?-TN2 family of ICs for non-isolated off-line power 2. Mostly discontinuous conduction mode. supplies provide dramatically improved performance compared to 3. Continuous conduction mode. 4. Packages: P: PDIP-8C, G: SMD-8C, D: SO-8C. traditional linear or cap-dropper solutions. Designs using the highly integrated LinkSwitch-TN2 ICs are more flexible and feature increased efficiency, comprehensive system level protection and higher reliability. The device family supports buck, buck-boost and flyback converter BYPASS pin capacitor value. The high current limit level provides topologies. Each device incorporates a 725 V power MOSFET, oscillator, maximum continuous output current while the low level permits using On/Off control for highest efficiency at light load, a high-voltage very low cost and small surface mount inductors. A full suite of switched current source for self-biasing, frequency jittering, fast protection features enable safe and reliable power supplies protecting (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output the device and the system against input and output overvoltage faults, and input overvoltage protection circuitry onto a monolithic IC. device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. LinkSwitch-TN2 ICs consume very little current in standby resulting in power supply designs that meet all no-load and standby specifications The device family is available in three different packages: PDIP-8C, worldwide. MOSFET current limit modes can be selected through the SO-8C, and SMD-8C. www.power.com January 2017 This Product is Covered by Patents and/or Pending Patent Applications. +LNK3202/3204-6 BYPASS DRAIN (BP/M) (D) REGULATOR 5.0 V FAULT I I FBSD FB PRESENT BYPASS PIN CAPACITOR 5.2 V DETECT AUTO-RESTART BYPASS PIN COUNTER UNDERVOLTAGE OVL + CURRENT LIMIT CLOCK COMPARATOR 5.0 V - RESET 4.5 V V I LIMIT JITTER CLOCK THERMAL SHUTDOWN DC MAX OSCILLATOR S Q FEEDBACK (FB) R Q 2.0 V -V T LEADING EDGE BLANKING OVP DETECT SOURCE (S) PI-7879-100416 Figure 3. Functional Block Diagram. Pin Functional Description SOURCE (S) Pin: This pin is the power MOSFET source connection. It is also the DRAIN (D) Pin: ground reference for the BYPASS and FEEDBACK pins. Power MOSFET drain connection. Provides internal operating current for both start-up and steady-state operation. BYPASS (BP/M) Pin: This pin has multiple functions: P Package (DIP-8C) ? It is the connection point for an external bypass capacitor for the G Package (SMD-8C) D Package (SO-8C) internally generated 5.0 V supply. ? It is a mode selector for the current limit value, depending on the value of the capacitance added. Use of a 0.1 ?F capacitor results 1 8 in the standard current limit value. Use of a 1 ?F capacitor results BP/M 1 8 S BP/M S in the current limit being reduced, allowing design with lowest cost 2 7 2 7 FB S FB S surface mount buck chokes. ? It provides a shutdown function. When the current into the BYPASS 6 S 6 S pin exceeds I for a time equal to 2 to 3 cycles of the internal BPSD 4 5 oscilator (f ), the device enters auto-restart. This can be used to D S OSC 4 5 D S provide an output overvoltage protection function with external circuitry. FEEDBACK (FB) Pin: During normal operation, switching of the power MOSFET is con- PI-7842-022416 trolled by the FEEDBACK pin. MOSFET switching is terminated when a current greater than I (49 ?A) is delivered into this pin. Line Figure 4. Pin Configuration. FB overvoltage protection is detected when a current greater than I FBSD (670 ?A) is delivered into this pin for 2 consecutive switching cycles. 2 Rev. F 01/17 www.power.com - +LNK3202/3204-6 600 LinkSwitch-TN2 Functional Description LinkSwitch-TN2 combines a high-voltage power MOSFET switch with 500 a power supply controller in one device. Unlike conventional PWM V DRAIN (pulse width modulator) controllers, LinkSwitch-TN2 uses a simple 400 ON/OFF control to regulate the output voltage. The LinkSwitch-TN2 controller consists of an oscillator, feedback (sense and logic) circuit, 300 5.0 V regulator, BYPASS pin undervoltage circuit, over-temperature protection, line and output overvoltage protection, frequency jittering, 200 current limit circuit, leading edge blanking and a 725 V power MOSFET. The LinkSwitch-TN2 incorporates additional circuitry for 100 auto-restart. Oscillator 0 The typical oscillator frequency is internally set to an average of f 68 kHz OSC (66 kHz). Two signals are generated from the oscillator: the maximum 64 kHz duty cycle signal (DC ) and the clock signal that indicates the (MAX) beginning of each cycle. 020 The LinkSwitch-TN2 oscillator incorporates circuitry that introduces a Time (?s) small amount of frequency jitter, typically 4 kHz peak-to-peak, to minimize EMI emission. The modulation rate of the frequency jitter is Figure 5. Frequency Jitter. set to 1 kHz to optimize EMI reduction for both average and quasi- peak emissions. The frequency jitter should be measured with the BYPASS Pin Undervoltage oscilloscope triggered at the falling edge of the DRAIN waveform. The BYPASS pin undervoltage circuitry disables the power MOSFET The waveform in Figure 5 illustrates the frequency jitter of the when the BYPASS pin voltage drops below V ?V (approximately 4.5 V). BP BPH LinkSwitch-TN2. Once the BYPASS pin voltage drops below this threshold, it must rise back to V to enable (turn-on) the power MOSFET. BP Feedback Input Circuit The feedback input circuit at the FEEDBACK pin consists of a low Over-Temperature Protection impedance source follower output set at V (2.0 V). When the The thermal shutdown circuitry senses the die temperature. The FB current delivered into this pin exceeds I (49 ?A), a low logic level threshold is set at T (142 ?C typical) with a 75 ?C (T ) hysteresis. SD SDH FB (disable) is generated at the output of the feedback circuit. This When the die temperature rises above T the power MOSFET is SD output is sampled at the beginning of each cycle on the rising edge disabled and remains disabled until the die temperature falls to of the clock signal. If high, the power MOSFET is turned on for that T ?T , at which point it is re-enabled. SD SDH cycle (enabled), otherwise the power MOSFET remains off (disabled). Current Limit The sampling is done only at the beginning of each cycle. Subse- The current limit circuit senses the current in the power MOSFET. quent changes in the FEEDBACK pin voltage or current during the When this current exceeds the internal threshold (I ), the power LIMIT remainder of the cycle do not impact the MOSFET enable/disable MOSFET is turned off for the remainder of that cycle. The leading status. If a current greater than I is injected into the feedback pin FBSD edge blanking circuit inhibits the current limit comparator for a short while the MOSFET is enabled for at least two consecutive cycles the time (t ) after the power MOSFET is turned on. This leading edge LEB part will stop switching and enter auto-restart off-time. Normal blanking time has been set so that current spikes caused by capaci- switching resumes after the auto-restart off-time expires. This tance and rectiefi r reverse recovery time will not cause premature shutdown function allows implementing line overvoltage protection in termination of the switching pulse. Current limit can be selected using flyback converters (see Figure 6). The current into the FEEDBACK pin the BYPASS pin capacitor (0.1 ?F for normal current limit / 1 ?F for should be limited to less than 1.2 mA. reduced current limit). LinkSwitch-TN2 selects between normal and 5.0 V Regulator and 5.2 V Shunt Voltage Clamp reduced current limit at power-up prior to switching. The 5.0 V regulator charges the bypass capacitor connected to the Auto-Restart BYPASS pin to V by drawing a current from the voltage on the BP In the event of a fault condition such as output overload, output DRAIN, whenever the MOSFET is off. The BYPASS pin is the internal short, or an open-loop condition, LinkSwitch-TN2 enters into supply voltage node for the LinkSwitch-TN2. When the MOSFET is auto-restart operation. An internal counter clocked by the oscillator on, the LinkSwitch-TN2 runs off of the energy stored in the bypass gets reset every time the FEEDBACK pin is pulled high. If the capacitor. Extremely low power consumption of the internal circuitry FEEDBACK pin is not pulled high for t (50 ms), the power AR(ON) allows the LinkSwitch-TN2 to operate continuously from the current MOSFET switching is disabled for a time equal to the auto-restart drawn from the DRAIN pin. A bypass capacitor value of 0.1 ?F is off-time. The first time a fault is asserted the off-time is 150 ms sufficient for both high frequency decoupling and energy storage. (t First Off Period). If the fault condition persists, subsequent AR(OFF) In addition, there is a shunt regulator clamping the BYPASS pin at off-times are 1500 ms long (t Subsequent Periods). The AR(OFF) V (5.2 V) when current is provided to the BYPASS pin through auto-restart alternately enables and disables the switching of the BP(SHUNT) an external resistor. This facilitates powering of LinkSwitch-TN2 power MOSFET until the fault condition is removed. The auto-restart externally through a bias winding to decrease the no-load consump- counter is gated by the switch oscillator. tion to about 10 mW (flyback). The device stops switching instantly and enters auto-restart when a current ?I is delivered into the BPSD BYPASS pin. Adding an external Zener diode from the output voltage to the BYPASS pin allows implementing an hysteretic OVP function in a flyback converter (see Figure 6). The current into the BYPASS pin should be limited to less than 16 mA. 3 Rev. F 01/17 www.power.com PI-3660-081303LNK3202/3204-6 LinkSwitch-TN2 Family Highly Energy Efficient Off-line Switcher IC with Integrated System Level Protection for Low Component-Count Power Supplies Product Highlights Highest Performance and Design Flexibility ? Supports buck, buck-boost and flyback topologies ? Low component-count buck converter FB BP/M ? Excellent load and line regulation ? Selectable device current limit D S + ? High current limit extends peak power and maximizes continuous LinkSwitch-TN2 Wide Range DC output power High-Voltage Output DC Input ? Low current limit allows the use of lowest-cost surface mount buck chokes ? 66 kHz operation with accurate current limit PI-7841-041816 ? Allows the use of low-cost off-the-shelf inductors Figure 1. Typical Buck Converter Application (See Application Examples ? Reduces size and cost of magnetics and output capacitor Section for Other Circuit Configurations). ? Frequency jittering reduces EMI lfi ter complexity ? Pin-out simpliefi s PCB heat sinking Enhanced Safety and Reliability Features ? Auto-restart for short-circuit and open loop faults ? Limits power delivery to 3% of maximum during a fault ? Output overvoltage protection (OVP) ? Line input overvoltage protection (OVL) ? Hysteretic over-temperature protection (OTP) ? Extended creepage between DRAIN pin and all other pins improves Figure 2. Package Options. P: PDIP-8C, G: SMD-8C, D: SO-8C. field reliability ? 725 V MOSFET rating for excellent surge withstand ? Extremely low component count enhances reliability 1 ? Allows single-sided PCB and full SMD manufacturability Output Current Table ? 230 VAC ?15% 85-265 VAC EcoSmart ? Extremely Energy Efficient 4 Product 2 3 2 3 ? Standby supply current <100 ?A MDCM CCM MDCM CCM ? On/Off control provides constant efcfi iency over a wide load range LNK3202P/G/D 63 mA 80 mA 63 mA 80 mA ? Easily meets all global energy efcfi iency regulations LNK3204P/G/D 120 mA 170 mA 120 mA 170 mA ? No-load <30 mW in high-side buck converters with external bias ? No-load <10 mW in yfl back converters with external bias LNK3205P/G/D 175 mA 270 mA 175 mA 270 mA LNK3206P/G/D 225 mA 360 mA 225 mA 360 mA Applications ? Appliances Table 1. Output Current Table. ? Metering Notes: ? Smart LED drivers and industrial controls 1. Typical output current in a non-isolated buck converter with devices operating ? IOT, home and building automation at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. See Key Description Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. The LinkSwitch?-TN2 family of ICs for non-isolated off-line power 2. Mostly discontinuous conduction mode. supplies provide dramatically improved performance compared to 3. Continuous conduction mode. 4. Packages: P: PDIP-8C, G: SMD-8C, D: SO-8C. traditional linear or cap-dropper solutions. Designs using the highly integrated LinkSwitch-TN2 ICs are more flexible and feature increased efficiency, comprehensive system level protection and higher reliability. The device family supports buck, buck-boost and flyback converter BYPASS pin capacitor value. The high current limit level provides topologies. Each device incorporates a 725 V power MOSFET, oscillator, maximum continuous output current while the low level permits using On/Off control for highest efficiency at light load, a high-voltage very low cost and small surface mount inductors. A full suite of switched current source for self-biasing, frequency jittering, fast protection features enable safe and reliable power supplies protecting (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output the device and the system against input and output overvoltage faults, and input overvoltage protection circuitry onto a monolithic IC. device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. LinkSwitch-TN2 ICs consume very little current in standby resulting in power supply designs that meet all no-load and standby specifications The device family is available in three different packages: PDIP-8C, worldwide. MOSFET current limit modes can be selected through the SO-8C, and SMD-8C. www.power.com January 2017 This Product is Covered by Patents and/or Pending Patent Applications. +LNK3202/3204-6 LinkSwitch-TN2 Family Highly Energy Efficient Off-line Switcher IC with Integrated System Level Protection for Low Component-Count Power Supplies Product Highlights Highest Performance and Design Flexibility ? Supports buck, buck-boost and flyback topologies ? Low component-count buck converter FB BP/M ? Excellent load and line regulation ? Selectable device current limit D S + ? High current limit extends peak power and maximizes continuous LinkSwitch-TN2 Wide Range DC output power High-Voltage Output DC Input ? Low current limit allows the use of lowest-cost surface mount buck chokes ? 66 kHz operation with accurate current limit PI-7841-041816 ? Allows the use of low-cost off-the-shelf inductors Figure 1. Typical Buck Converter Application (See Application Examples ? Reduces size and cost of magnetics and output capacitor Section for Other Circuit Configurations). ? Frequency jittering reduces EMI lfi ter complexity ? Pin-out simpliefi s PCB heat sinking Enhanced Safety and Reliability Features ? Auto-restart for short-circuit and open loop faults ? Limits power delivery to 3% of maximum during a fault ? Output overvoltage protection (OVP) ? Line input overvoltage protection (OVL) ? Hysteretic over-temperature protection (OTP) ? Extended creepage between DRAIN pin and all other pins improves Figure 2. Package Options. P: PDIP-8C, G: SMD-8C, D: SO-8C. field reliability ? 725 V MOSFET rating for excellent surge withstand ? Extremely low component count enhances reliability 1 ? Allows single-sided PCB and full SMD manufacturability Output Current Table ? 230 VAC ?15% 85-265 VAC EcoSmart ? Extremely Energy Efficient 4 Product 2 3 2 3 ? Standby supply current <100 ?A MDCM CCM MDCM CCM ? On/Off control provides constant efcfi iency over a wide load range LNK3202P/G/D 63 mA 80 mA 63 mA 80 mA ? Easily meets all global energy efcfi iency regulations LNK3204P/G/D 120 mA 170 mA 120 mA 170 mA ? No-load <30 mW in high-side buck converters with external bias ? No-load <10 mW in yfl back converters with external bias LNK3205P/G/D 175 mA 270 mA 175 mA 270 mA LNK3206P/G/D 225 mA 360 mA 225 mA 360 mA Applications ? Appliances Table 1. Output Current Table. ? Metering Notes: ? Smart LED drivers and industrial controls 1. Typical output current in a non-isolated buck converter with devices operating ? IOT, home and building automation at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. See Key Description Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. The LinkSwitch?-TN2 family of ICs for non-isolated off-line power 2. Mostly discontinuous conduction mode. supplies provide dramatically improved performance compared to 3. Continuous conduction mode. 4. Packages: P: PDIP-8C, G: SMD-8C, D: SO-8C. traditional linear or cap-dropper solutions. Designs using the highly integrated LinkSwitch-TN2 ICs are more flexible and feature increased efficiency, comprehensive system level protection and higher reliability. The device family supports buck, buck-boost and flyback converter BYPASS pin capacitor value. The high current limit level provides topologies. Each device incorporates a 725 V power MOSFET, oscillator, maximum continuous output current while the low level permits using On/Off control for highest efficiency at light load, a high-voltage very low cost and small surface mount inductors. A full suite of switched current source for self-biasing, frequency jittering, fast protection features enable safe and reliable power supplies protecting (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output the device and the system against input and output overvoltage faults, and input overvoltage protection circuitry onto a monolithic IC. device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. LinkSwitch-TN2 ICs consume very little current in standby resulting in power supply designs that meet all no-load and standby specifications The device family is available in three different packages: PDIP-8C, worldwide. MOSFET current limit modes can be selected through the SO-8C, and SMD-8C. www.power.com January 2017 This Product is Covered by Patents and/or Pending Patent Applications. +LNK3202/3204-6 BYPASS DRAIN (BP/M) (D) REGULATOR 5.0 V FAULT I I FBSD FB PRESENT BYPASS PIN CAPACITOR 5.2 V DETECT AUTO-RESTART BYPASS PIN COUNTER UNDERVOLTAGE OVL + CURRENT LIMIT CLOCK COMPARATOR 5.0 V - RESET 4.5 V V I LIMIT JITTER CLOCK THERMAL SHUTDOWN DC MAX OSCILLATOR S Q FEEDBACK (FB) R Q 2.0 V -V T LEADING EDGE BLANKING OVP DETECT SOURCE (S) PI-7879-100416 Figure 3. Functional Block Diagram. Pin Functional Description SOURCE (S) Pin: This pin is the power MOSFET source connection. It is also the DRAIN (D) Pin: ground reference for the BYPASS and FEEDBACK pins. Power MOSFET drain connection. Provides internal operating current for both start-up and steady-state operation. BYPASS (BP/M) Pin: This pin has multiple functions: P Package (DIP-8C) ? It is the connection point for an external bypass capacitor for the G Package (SMD-8C) D Package (SO-8C) internally generated 5.0 V supply. ? It is a mode selector for the current limit value, depending on the value of the capacitance added. Use of a 0.1 ?F capacitor results 1 8 in the standard current limit value. Use of a 1 ?F capacitor results BP/M 1 8 S BP/M S in the current limit being reduced, allowing design with lowest cost 2 7 2 7 FB S FB S surface mount buck chokes. ? It provides a shutdown function. When the current into the BYPASS 6 S 6 S pin exceeds I for a time equal to 2 to 3 cycles of the internal BPSD 4 5 oscilator (f ), the device enters auto-restart. This can be used to D S OSC 4 5 D S provide an output overvoltage protection function with external circuitry. FEEDBACK (FB) Pin: During normal operation, switching of the power MOSFET is con- PI-7842-022416 trolled by the FEEDBACK pin. MOSFET switching is terminated when a current greater than I (49 ?A) is delivered into this pin. Line Figure 4. Pin Configuration. FB overvoltage protection is detected when a current greater than I FBSD (670 ?A) is delivered into this pin for 2 consecutive switching cycles. 2 Rev. F 01/17 www.power.com - +LNK3202/3204-6 LinkSwitch-TN2 Family Highly Energy Efficient Off-line Switcher IC with Integrated System Level Protection for Low Component-Count Power Supplies Product Highlights Highest Performance and Design Flexibility ? Supports buck, buck-boost and flyback topologies ? Low component-count buck converter FB BP/M ? Excellent load and line regulation ? Selectable device current limit D S + ? High current limit extends peak power and maximizes continuous LinkSwitch-TN2 Wide Range DC output power High-Voltage Output DC Input ? Low current limit allows the use of lowest-cost surface mount buck chokes ? 66 kHz operation with accurate current limit PI-7841-041816 ? Allows the use of low-cost off-the-shelf inductors Figure 1. Typical Buck Converter Application (See Application Examples ? Reduces size and cost of magnetics and output capacitor Section for Other Circuit Configurations). ? Frequency jittering reduces EMI lfi ter complexity ? Pin-out simpliefi s PCB heat sinking Enhanced Safety and Reliability Features ? Auto-restart for short-circuit and open loop faults ? Limits power delivery to 3% of maximum during a fault ? Output overvoltage protection (OVP) ? Line input overvoltage protection (OVL) ? Hysteretic over-temperature protection (OTP) ? Extended creepage between DRAIN pin and all other pins improves Figure 2. Package Options. P: PDIP-8C, G: SMD-8C, D: SO-8C. field reliability ? 725 V MOSFET rating for excellent surge withstand ? Extremely low component count enhances reliability 1 ? Allows single-sided PCB and full SMD manufacturability Output Current Table ? 230 VAC ?15% 85-265 VAC EcoSmart ? Extremely Energy Efficient 4 Product 2 3 2 3 ? Standby supply current <100 ?A MDCM CCM MDCM CCM ? On/Off control provides constant efcfi iency over a wide load range LNK3202P/G/D 63 mA 80 mA 63 mA 80 mA ? Easily meets all global energy efcfi iency regulations LNK3204P/G/D 120 mA 170 mA 120 mA 170 mA ? No-load <30 mW in high-side buck converters with external bias ? No-load <10 mW in yfl back converters with external bias LNK3205P/G/D 175 mA 270 mA 175 mA 270 mA LNK3206P/G/D 225 mA 360 mA 225 mA 360 mA Applications ? Appliances Table 1. Output Current Table. ? Metering Notes: ? Smart LED drivers and industrial controls 1. Typical output current in a non-isolated buck converter with devices operating ? IOT, home and building automation at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. See Key Description Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. The LinkSwitch?-TN2 family of ICs for non-isolated off-line power 2. Mostly discontinuous conduction mode. supplies provide dramatically improved performance compared to 3. Continuous conduction mode. 4. Packages: P: PDIP-8C, G: SMD-8C, D: SO-8C. traditional linear or cap-dropper solutions. Designs using the highly integrated LinkSwitch-TN2 ICs are more flexible and feature increased efficiency, comprehensive system level protection and higher reliability. The device family supports buck, buck-boost and flyback converter BYPASS pin capacitor value. The high current limit level provides topologies. Each device incorporates a 725 V power MOSFET, oscillator, maximum continuous output current while the low level permits using On/Off control for highest efficiency at light load, a high-voltage very low cost and small surface mount inductors. A full suite of switched current source for self-biasing, frequency jittering, fast protection features enable safe and reliable power supplies protecting (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output the device and the system against input and output overvoltage faults, and input overvoltage protection circuitry onto a monolithic IC. device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. LinkSwitch-TN2 ICs consume very little current in standby resulting in power supply designs that meet all no-load and standby specifications The device family is available in three different packages: PDIP-8C, worldwide. MOSFET current limit modes can be selected through the SO-8C, and SMD-8C. www.power.com January 2017 This Product is Covered by Patents and/or Pending Patent Applications. +LNK3202/3204-6 LinkSwitch-TN2 Family Highly Energy Efficient Off-line Switcher IC with Integrated System Level Protection for Low Component-Count Power Supplies Product Highlights Highest Performance and Design Flexibility ? Supports buck, buck-boost and flyback topologies ? Low component-count buck converter FB BP/M ? Excellent load and line regulation ? Selectable device current limit D S + ? High current limit extends peak power and maximizes continuous LinkSwitch-TN2 Wide Range DC output power High-Voltage Output DC Input ? Low current limit allows the use of lowest-cost surface mount buck chokes ? 66 kHz operation with accurate current limit PI-7841-041816 ? Allows the use of low-cost off-the-shelf inductors Figure 1. Typical Buck Converter Application (See Application Examples ? Reduces size and cost of magnetics and output capacitor Section for Other Circuit Configurations). ? Frequency jittering reduces EMI lfi ter complexity ? Pin-out simpliefi s PCB heat sinking Enhanced Safety and Reliability Features ? Auto-restart for short-circuit and open loop faults ? Limits power delivery to 3% of maximum during a fault ? Output overvoltage protection (OVP) ? Line input overvoltage protection (OVL) ? Hysteretic over-temperature protection (OTP) ? Extended creepage between DRAIN pin and all other pins improves Figure 2. Package Options. P: PDIP-8C, G: SMD-8C, D: SO-8C. field reliability ? 725 V MOSFET rating for excellent surge withstand ? Extremely low component count enhances reliability 1 ? Allows single-sided PCB and full SMD manufacturability Output Current Table ? 230 VAC ?15% 85-265 VAC EcoSmart ? Extremely Energy Efficient 4 Product 2 3 2 3 ? Standby supply current <100 ?A MDCM CCM MDCM CCM ? On/Off control provides constant efcfi iency over a wide load range LNK3202P/G/D 63 mA 80 mA 63 mA 80 mA ? Easily meets all global energy efcfi iency regulations LNK3204P/G/D 120 mA 170 mA 120 mA 170 mA ? No-load <30 mW in high-side buck converters with external bias ? No-load <10 mW in yfl back converters with external bias LNK3205P/G/D 175 mA 270 mA 175 mA 270 mA LNK3206P/G/D 225 mA 360 mA 225 mA 360 mA Applications ? Appliances Table 1. Output Current Table. ? Metering Notes: ? Smart LED drivers and industrial controls 1. Typical output current in a non-isolated buck converter with devices operating ? IOT, home and building automation at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. See Key Description Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. The LinkSwitch?-TN2 family of ICs for non-isolated off-line power 2. Mostly discontinuous conduction mode. supplies provide dramatically improved performance compared to 3. Continuous conduction mode. 4. Packages: P: PDIP-8C, G: SMD-8C, D: SO-8C. traditional linear or cap-dropper solutions. Designs using the highly integrated LinkSwitch-TN2 ICs are more flexible and feature increased efficiency, comprehensive system level protection and higher reliability. The device family supports buck, buck-boost and flyback converter BYPASS pin capacitor value. The high current limit level provides topologies. Each device incorporates a 725 V power MOSFET, oscillator, maximum continuous output current while the low level permits using On/Off control for highest efficiency at light load, a high-voltage very low cost and small surface mount inductors. A full suite of switched current source for self-biasing, frequency jittering, fast protection features enable safe and reliable power supplies protecting (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output the device and the system against input and output overvoltage faults, and input overvoltage protection circuitry onto a monolithic IC. device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. LinkSwitch-TN2 ICs consume very little current in standby resulting in power supply designs that meet all no-load and standby specifications The device family is available in three different packages: PDIP-8C, worldwide. MOSFET current limit modes can be selected through the SO-8C, and SMD-8C. www.power.com January 2017 This Product is Covered by Patents and/or Pending Patent Applications. +LNK3202/3204-6 BYPASS DRAIN (BP/M) (D) REGULATOR 5.0 V FAULT I I FBSD FB PRESENT BYPASS PIN CAPACITOR 5.2 V DETECT AUTO-RESTART BYPASS PIN COUNTER UNDERVOLTAGE OVL + CURRENT LIMIT CLOCK COMPARATOR 5.0 V - RESET 4.5 V V I LIMIT JITTER CLOCK THERMAL SHUTDOWN DC MAX OSCILLATOR S Q FEEDBACK (FB) R Q 2.0 V -V T LEADING EDGE BLANKING OVP DETECT SOURCE (S) PI-7879-100416 Figure 3. Functional Block Diagram. Pin Functional Description SOURCE (S) Pin: This pin is the power MOSFET source connection. It is also the DRAIN (D) Pin: ground reference for the BYPASS and FEEDBACK pins. Power MOSFET drain connection. Provides internal operating current for both start-up and steady-state operation. BYPASS (BP/M) Pin: This pin has multiple functions: P Package (DIP-8C) ? It is the connection point for an external bypass capacitor for the G Package (SMD-8C) D Package (SO-8C) internally generated 5.0 V supply. ? It is a mode selector for the current limit value, depending on the value of the capacitance added. Use of a 0.1 ?F capacitor results 1 8 in the standard current limit value. Use of a 1 ?F capacitor results BP/M 1 8 S BP/M S in the current limit being reduced, allowing design with lowest cost 2 7 2 7 FB S FB S surface mount buck chokes. ? It provides a shutdown function. When the current into the BYPASS 6 S 6 S pin exceeds I for a time equal to 2 to 3 cycles of the internal BPSD 4 5 oscilator (f ), the device enters auto-restart. This can be used to D S OSC 4 5 D S provide an output overvoltage protection function with external circuitry. FEEDBACK (FB) Pin: During normal operation, switching of the power MOSFET is con- PI-7842-022416 trolled by the FEEDBACK pin. MOSFET switching is terminated when a current greater than I (49 ?A) is delivered into this pin. Line Figure 4. Pin Configuration. FB overvoltage protection is detected when a current greater than I FBSD (670 ?A) is delivered into this pin for 2 consecutive switching cycles. 2 Rev. F 01/17 www.power.com - +LNK3202/3204-6 600 LinkSwitch-TN2 Functional Description LinkSwitch-TN2 combines a high-voltage power MOSFET switch with 500 a power supply controller in one device. Unlike conventional PWM V DRAIN (pulse width modulator) controllers, LinkSwitch-TN2 uses a simple 400 ON/OFF control to regulate the output voltage. The LinkSwitch-TN2 controller consists of an oscillator, feedback (sense and logic) circuit, 300 5.0 V regulator, BYPASS pin undervoltage circuit, over-temperature protection, line and output overvoltage protection, frequency jittering, 200 current limit circuit, leading edge blanking and a 725 V power MOSFET. The LinkSwitch-TN2 incorporates additional circuitry for 100 auto-restart. Oscillator 0 The typical oscillator frequency is internally set to an average of f 68 kHz OSC (66 kHz). Two signals are generated from the oscillator: the maximum 64 kHz duty cycle signal (DC ) and the clock signal that indicates the (MAX) beginning of each cycle. 020 The LinkSwitch-TN2 oscillator incorporates circuitry that introduces a Time (?s) small amount of frequency jitter, typically 4 kHz peak-to-peak, to minimize EMI emission. The modulation rate of the frequency jitter is Figure 5. Frequency Jitter. set to 1 kHz to optimize EMI reduction for both average and quasi- peak emissions. The frequency jitter should be measured with the BYPASS Pin Undervoltage oscilloscope triggered at the falling edge of the DRAIN waveform. The BYPASS pin undervoltage circuitry disables the power MOSFET The waveform in Figure 5 illustrates the frequency jitter of the when the BYPASS pin voltage drops below V ?V (approximately 4.5 V). BP BPH LinkSwitch-TN2. Once the BYPASS pin voltage drops below this threshold, it must rise back to V to enable (turn-on) the power MOSFET. BP Feedback Input Circuit The feedback input circuit at the FEEDBACK pin consists of a low Over-Temperature Protection impedance source follower output set at V (2.0 V). When the The thermal shutdown circuitry senses the die temperature. The FB current delivered into this pin exceeds I (49 ?A), a low logic level threshold is set at T (142 ?C typical) with a 75 ?C (T ) hysteresis. SD SDH FB (disable) is generated at the output of the feedback circuit. This When the die temperature rises above T the power MOSFET is SD output is sampled at the beginning of each cycle on the rising edge disabled and remains disabled until the die temperature falls to of the clock signal. If high, the power MOSFET is turned on for that T ?T , at which point it is re-enabled. SD SDH cycle (enabled), otherwise the power MOSFET remains off (disabled). Current Limit The sampling is done only at the beginning of each cycle. Subse- The current limit circuit senses the current in the power MOSFET. quent changes in the FEEDBACK pin voltage or current during the When this current exceeds the internal threshold (I ), the power LIMIT remainder of the cycle do not impact the MOSFET enable/disable MOSFET is turned off for the remainder of that cycle. The leading status. If a current greater than I is injected into the feedback pin FBSD edge blanking circuit inhibits the current limit comparator for a short while the MOSFET is enabled for at least two consecutive cycles the time (t ) after the power MOSFET is turned on. This leading edge LEB part will stop switching and enter auto-restart off-time. Normal blanking time has been set so that current spikes caused by capaci- switching resumes after the auto-restart off-time expires. This tance and rectiefi r reverse recovery time will not cause premature shutdown function allows implementing line overvoltage protection in termination of the switching pulse. Current limit can be selected using flyback converters (see Figure 6). The current into the FEEDBACK pin the BYPASS pin capacitor (0.1 ?F for normal current limit / 1 ?F for should be limited to less than 1.2 mA. reduced current limit). LinkSwitch-TN2 selects between normal and 5.0 V Regulator and 5.2 V Shunt Voltage Clamp reduced current limit at power-up prior to switching. The 5.0 V regulator charges the bypass capacitor connected to the Auto-Restart BYPASS pin to V by drawing a current from the voltage on the BP In the event of a fault condition such as output overload, output DRAIN, whenever the MOSFET is off. The BYPASS pin is the internal short, or an open-loop condition, LinkSwitch-TN2 enters into supply voltage node for the LinkSwitch-TN2. When the MOSFET is auto-restart operation. An internal counter clocked by the oscillator on, the LinkSwitch-TN2 runs off of the energy stored in the bypass gets reset every time the FEEDBACK pin is pulled high. If the capacitor. Extremely low power consumption of the internal circuitry FEEDBACK pin is not pulled high for t (50 ms), the power AR(ON) allows the LinkSwitch-TN2 to operate continuously from the current MOSFET switching is disabled for a time equal to the auto-restart drawn from the DRAIN pin. A bypass capacitor value of 0.1 ?F is off-time. The first time a fault is asserted the off-time is 150 ms sufficient for both high frequency decoupling and energy storage. (t First Off Period). If the fault condition persists, subsequent AR(OFF) In addition, there is a shunt regulator clamping the BYPASS pin at off-times are 1500 ms long (t Subsequent Periods). The AR(OFF) V (5.2 V) when current is provided to the BYPASS pin through auto-restart alternately enables and disables the switching of the BP(SHUNT) an external resistor. This facilitates powering of LinkSwitch-TN2 power MOSFET until the fault condition is removed. The auto-restart externally through a bias winding to decrease the no-load consump- counter is gated by the switch oscillator. tion to about 10 mW (flyback). The device stops switching instantly and enters auto-restart when a current =I is delivered into the BPSD BYPASS pin. Adding an external Zener diode from the output voltage to the BYPASS pin allows implementing an hysteretic OVP function in a flyback converter (see Figure 6). The current into the BYPASS pin should be limited to less than 16 mA. 3 Rev. F 01/17 www.power.com PI-3660-081303