Supertex inc. HV9912DB1 High Brightness Boost LED Driver Demoboard with 1:3000 Dimming Ratio and Hiccup Mode Protection General Description Specifications The HV9912DB1 is an LED driver demoboard capable of driving up Parameter Value to 20 one-watt LEDs in series from an input of 21 - 27VDC. It uses Input voltage (steady state): 21 - 27VDC the Supertex HV9912 in a boost topology. The converter has very good initial regulation (+/-5%) and excellent line and load regulation Output LED string voltage: 35V min - 80V max over the entire input and output voltage range (<+/- 1%). The full Output current: 350mA +/-5% load efficiency of the converter is typically greater than 90%. Output current ripple: 10% typical The HV9912DB1 is protected against open LED and output short Switching frequency: 200kHz circuit conditions. It is also protected under input under-voltage Full load efficiency: 93% (at 24V input) conditions by limiting the input current. It has an excellent PWM dimming response, with typical rise and fall times less than 1.0s, Open LED protection: Shuts down at 92V which allows high PWM dimming ratios. The switching frequency of Output short circuit Included the HV9912DB1 can be synchronized to other HV9912 boards or protection: to an external 200kHz clock by connecting the clock to the SYNC Input under voltage Included pin of the HV9912DB1. protection: 1:3000 dimming ratio PWM dimming: The HV9912DB1 features hiccup mode short circuit and open LED at 200Hz protection. Upon detection of either fault condition, the IC shuts down the driver and periodically attemps to restart until the fault condition ends. The HV9912DB1 also features a built-in 500ns blanking to prevent false tripping of the over-current comparator due to parasitic capacitance spikes during PWM dimming. Board Layout and Connection Diagram V IN + Actual size: 64.0mm x 34.5mm Connections SYNC - To synchronize two or more boards, connect the Input - The input is connected between the terminals of SYNC pins of all the boards together. To synchronize the connector J1 as shown in the Connection Diagram. HV9912DB1 to an external 200kHz clock, connect the clock between the SYNC and GND pins of terminal J3. Output - The output is connected between the terminals of connector J2 as shown. Note: During PWM dimming, pin 2 of connector J3 should be left Enable/PWM Dimming - To just enable the board, short pins open. Also, the PWM signal must have the proper polarity PWMD and VDD of connector J3 as shown by the dashed with the positive connected to pin 3 of J3. Note that pin 4 lines. To PWM dim the board, connect the external push- of J3 is internally connected to the return path of the input pull waveform source between terminals PWMD and GND voltage. of connector J3 as shown by the solid lines. Doc. DSDB-HV9912DB1 Supertex inc. A032913 www.supertex.comHV9912DB1 Testing The Demoboard 95 Normal Operation: Connect the input source and the output LEDs as shown in the Connection Diagram and enable the 94 board. The LEDs will glow with a steady intensity. Connecting 93 an ammeter in series with the LEDs will allow measurement 92 of the LED current. The current will be 350mA +/- 5%. 91 90 Current Regulation: With the input power to the converter 35 40 45 50 55 60 65 70 75 80 disconnected, change the LED string voltage within Output Voltage (V) the specifications mentioned. The current output of the Fig. 1 Efficiency vs. Output Voltage HV9912DB1 will remain very steady over the entire load range. Vary the input voltage while the circuit is operational. 95 The current will be regulated over the entire line range. 94 93 Open LED test: Connect a voltmeter across the output 92 terminals of the HV9912DB1. Start the demoboard normally, 91 and once the LED current reaches steady state, unplug 90 one end of the LED string from the demoboard. The output 20 22 24 26 28 voltage will rise to about 92V and the HV9912DB1 will shut Input Voltage (V) down. Once the LED string is reconnected, the driver will Fig. 2 Efficiency vs. Input Voltage start regulating current. 2. Current Regulation: Figs. 3 and 4 show the output cur- Short Circuit Test: When the HV9912DB1 is operating in rent regulation vs. output voltage and input voltage respec- steady state, connect a jumper across the terminals of the tively. The total current regulation (line and load combined) LED string. Notice that the output current will immediately is found to be less than 1%. go to zero and the converter will shut down. Removing the 0.354 jumper will cause the HV9912DB1 to restart and continue to regulate the LED current. 0.352 0.350 PWM Dimming: With the input voltage to the board disconnected, apply a TTL compatible, push-pull square wave 0.348 signal between PWMD and GND terminals of connector J3 0.346 as shown in the Connection Diagram. Turn the input voltage 35 40 45 50 55 60 65 70 75 80 back on and adjust the duty cycle and/or frequency of the Output Voltage (V) PWM dimming signal. The output current will track the PWM Fig. 3 Output Current vs. Output Voltage dimming signal. Note that although the converter operates perfectly well at 1.0kHz PWM dimming frequency, the widest PWM dimming ratio can be obtained at lower frequencies 0.354 like 100 or 200Hz. 0.352 0.350 Typical Results 0.348 1. Efficiency: The efficiency of the converter at various LED 0.346 string voltages are shown in Fig.1 (measured at the nominal 20 22 24 26 28 input voltage of 24V). Fig.2 shows the full load efficiency Input Voltage (V) of the converter at varying input voltages. The minimum ef- Fig. 4 Output Current vs. Input Voltage ficiency of 93% for the converter occurs at 21V input and full load output. Doc. DSDB-HV9912DB1 Supertex inc. A032913 2 www.supertex.com Output Current (A) Efficiency (%) Efficiency (%) Output Current (A)