TC115 PFM/PWM Step-Up DC/DC Converter Features Package Type SOT-89-5 High Efficiency at Low Output Load Currents via PFM Mode PS 5 4 Assured Start-up at 0.9V 80 A (Typ) Supply Current GND LX 85% Typical Efficiency at 100 mA TC115 140 mA Typical Output Current V 2.0V IN NC PS SHDN Low Power Shutdown Mode 1 2 3 No External Switching Transistor Needed Space-Saving SOT-89 Package General Description Applications The TC115 is a high-efficiency step-up DC/DC Pagers converter for small, low input voltage or battery- Cellular Phones powered systems. This device has a start-up voltage Palmtops of 0.9V and a typical supply current of 80 A. Phase 1-Cell to 3-Cell Battery Powered Systems compensation and soft-start circuitry are included on- chip. Unlike conventional PWM step-up converters, Cameras, Video Recorders the TC115 automatically shifts to pulse frequency Local +3V to +5V Supplies modulation (PFM) at low loads, resulting in reduced supply current and improved efficiency. The TC115 requires only an external diode, an inductor and a capacitor, while supporting typical output cur- rents of 140 mA. Supply current is reduced to less than input is brought low. 0.5 A (max) when SHDN Small size, low installed cost and low supply current make the TC115 step-up converter ideal for use in a wide range of battery-powered systems. Functional Block Diagram L 1 100 H Sumida CD-54 D 1 +3V OUT + + C IN5817 + 1 1.5V PS C 10 F 2 5 4 47 F Tantalum GND LX TC115 NC PS SHDN 1 2 3 1.5V to +3V, 50 mA Supply 2002-2012 Microchip Technology Inc. DS21361D-page 1TC115 1.0 ELECTRICAL PIN FUNCTION TABLE CHARACTERISTICS Symbol Description Absolute Maximum Ratings NC Not connected Power Supply Voltage (PS)...............................................12V PS Power and voltage sense input Power Dissipation ......................................................500 mW SHDN Shutdown input LX Sink Current......................................................400 mA pk LX Inductor switch output SHDN Input Voltage ..........................................................12V GND Ground terminal Operating Temperature Range........................-40C to +85C Storage Temperature Range.........................-40C to +125C Stresses above those listed underAbsolute Maximum Rating may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of the specifications is not implied. Exposure to Absolute Maximum Rating conditions for extended periods may affect device reliability. DC CHARACTERISTICS Electrical Specifications: Unless otherwise noted, V = 5V, T = +25C. Circuit configuration is illustrated in Figure 5-1. OUT A Parameters Sym Min Typ Max Units Conditions Operating Supply Voltage V 0.9 10.0 V Note 5 IN Start-Up Supply Voltage V 0.9 VI = 1 mA START OUT LX Maximum Sink Current I 350 mA LXMAX LX Limit Frequency f 200 kHz V = VLX LIM LX LIM LX Limit Voltage VLX 0.7 1.3 V Note 2 LIM No Load Supply Current I 13 26 AI = 0, V = V x 0.8 (Note 3) DD OUT IN OUT Boost Mode Supply Current I 80 135 A No external components, CC V = (0.95 x V ) applied to PS (or IN OUT V ) input DD Standby Supply Current I 9 17 A No external components, STBY V = (1.1 x V ) applied to PS IN OUT (or V ) input DD Shutdown Supply Current I 0.5 A SHDN = 0V SD Oscillator Frequency f 85 100 115 kHz Note 2, Note 4 OSC Output Voltage V V x 0.975 V V x 1.025 V V = 2.2V minimum (Note 1) OUT R R R IN LX Output ON Resistance Rswon 1.4 2.4 V = 0.4V LX Duty Cycle PFMDUTY 10 17 25 % No external components (PFM Operating Mode) Maximum Duty Cycle MAX- 80 87 92 % Note 4 DUTY Soft Start Time t 4 10 20 msec SS Efficiency h 85 % SHDN Input Logic High V 0.75 V IH SHDN Input Logic Low V 0.20 V IL Note 1: V is the nominal factory-programmed output voltage setting. R 2: VLX is the voltage on the LX pin (with internal switch ON) that will cause the oscillator to run at twice nominal LIM frequency in to limit the switch current through the internal N-channel switching transistor. 3: Measured with D = MA735 (reverse current < 1 A at a reverse voltage of 10V). 1 4: With TC115 operating in PWM mode. 5: See Section 4.4, Behavior When V is Greater Than the Factory-Programmed V Setting. IN OUT DS21361D-page 2 2002-2012 Microchip Technology Inc.