TC105 PFM/PWM Step-Down DC/DC Controller Features Package Type 57 A (Typ) Supply Current 5-Pin SOT-23A 1A Output Current V SHDN OUT 0.5 A Shutdown Mode 5 4 300kHz Switching Frequency for Small Inductor Size Programmable Soft-Start TC105 92% Typical Efficiency Small Package: 5-Pin SOT-23A 1 23 V EXT GND DD Applications NOTE: 5-Pin SOT-23A is equivalent to the EIAJ SC-74A Palmtops Battery-Operated Systems General Description Portable Instruments Positive LCD Bias Generators The TC105 is a step-down (Buck) switching controller Portable Communicators that furnishes output currents of up to 1A (max) while delivering a typical efficiency of 92%. The TC105 Hand-Held Scanners normally operates in pulse width modulation mode 5V to 3V Down Converters (PWM), but automatically switches to pulse frequency modulation (PFM) at low output loads for greater Device Selection Table efficiency. Oscillator frequency is 300kHz, allowing use of small (22 H) inductors. Supply current draw is only Output Osc. Operating Part 102 A (max), and is reduced to less than 0.5 Awhen Voltage Package Freq. Temp. Number the SHDN input is brought low. Regulator operation is (V)* (kHz) Range suspended during shutdown. The TC105 accepts a TC105503ECT 5.0 5-Pin SOT-23A 300 -40Cto+85C maximum input voltage of 10V. TC105333ECT 3.3 5-Pin SOT-23A 300 -40Cto+85C TheTC105 is availableinasmall 5-PinSOT-23A TC105303ECT 3.0 5-Pin SOT-23A 300 -40Cto+85C package, occupies minimum board space and is ideal *Other output voltages are available. Please contact for a wide range of applications. Microchip Technology Inc. for details. Functional Block Diagram L 22 H (Sumida CD54) 1 3.3V V OUT R 470K SS OFF C2 ON D 47 F 1 (From System MA737 C Control Logic) SS 10V 0.033 F Tantalum 5 4 V OUT SHDN TC105333ECT V EXT DD GND 1 2 3 Si 9430 P + V BATT C 10 F/16V 1 6V NiMH 3.3V Regulated Supply Using 6V NiMH Battery Pack Input 2002 Microchip Technology Inc. DS21349B-page 1TC105 *Stresses above those listed underAbsolute Maximum 1.0 ELECTRICAL Rating may cause permanent damage to the device. These CHARACTERISTICS are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the Absolute Maximum Ratings* operation sections of the specifications is not implied. Exposure to Absolute Maximum Rating conditions for Voltage on V ....................................... -0.3V to +12V DD extended periods may affect device reliability. EXT Output Current ........................................100mA Voltage on V ,EXT, OUT SHDN Pins .....................................-0.3V to V +0.3V DD Power Dissipation.............................................150mW Operating Temperature Range.............-40C to +85C Storage Temperature Range ..............-40C to +125C TC105 ELECTRICAL SPECIFICATIONS Electrical Characteristics: Note 1, f =300 kHz T = 25C, unless otherwise noted. OSC A Symbol Parameter Min Typ Max Units Test Conditions V Operating Supply Voltage 2.2 10.0 V DD V Minimum Input Voltage 0.9 2.2 V EXT = High No external components DDMIN V = 0V, SHDN =V OUT IN I Operating Supply Current 57 102 A No external components V =3.0V, 3.3V DD R 67 122 V = 0V, SHDN =V V =5.0V OUT IN R I Standby Supply Current 15 27 A No external components V =3.0V, 3.3V STBY R 16 29 V =SHDN=V V =5.0V OUT IN R I Shutdown Supply Current 0.5 A SHDN =GND SHDN f Oscillator Frequency 255 300 345 kHz V =V +0.3V OSC IN OUT V Output Voltage V x0.975 V V x1.025 Note2 OUT R R R DTYMAX Maximum Duty Cycle (PWM Mode) 100 % DTYPFM Duty Cycle (PFM Mode) 15 25 35 % I =0mA OUT V SHDN Input Logic High 0.65 V V = 0V, No external components IH OUT V SHDN Input Logic Low 0.20 V V = 0V, No external components IL OUT REXTH EXT ON Resistance to V 17 24 No external components V =3.0V DD R 16 22 V =3.3V R 12 17 V =5.0V R V = SHDN=V ,V =(V 0.4V) OUT IN EXT IN REXTL EXT ON Resistance to GND 15 20 No external components V =3.0V R 14 19 V =3.3V R 10 14 V =5.0V R V = 0V, SHDN =V ,V =0.4V OUT IN EXT Efficiency 92 % Note 1: V =3.0V,V =4.5V, I = 200mA R IN OUT V =3.3V,V =5.0V, I = 220mA R IN OUT V =5.0V,V =7.5V, I = 320mA R IN OUT 2: V is the factory output voltage setting. R DS21349B-page 2 2002 Microchip Technology Inc.