SI9145

Si9145 Vishay Siliconix Low-Voltage Switchmode Controller FEATURES D D D D D D 2.7-V to 7-V Input Operating Range Voltage-Mode PWM Control High-Speed, Source-Sink Output Drive (200 mA) Internal Oscillator (up to 2 MHz) Standby Mode 0−100% Controllable Maximum Duty-Cycle DESCRIPTION The Si9145 switchmode controller IC is ideally suited for high efficiency dc/dc converters in low input voltage systems. Operation is guaranteed down to 2.7 V, with a minimum start-up voltage of 3.0 V making the Si9145 ideal for use with NiCd, NMH, and lithium ion battery packs. A mode select pin allows the output driver polarity to be programmed allowing the device to function as a step-up or step-down converter. Features include a precision bandgap reference, a wide bandwidth error amplifier, a 2-MHz oscillator, an input voltage monitor with standby mode and a 200-mA output driver. Supply current in normal operation is typically 1.1 mA and 250 mA in standby mode. The Si9145 implements conventional voltage mode control. The maximum duty cycle in boost mode can be limited by voltage on DMAX/SS pin. Frequency can be externally programmed by selection of ROSC and COSC. The Si9145 is available in both standard and lead (Pb)-free 16-pin SOIC and TSSOP packages and is specified over the industrial temperature range (−25_C to 85_C). FUNCTIONAL BLOCK DIAGRAM 1.5-V Reference Generator VDD UVLOSET UVLO VREF VUVLO ENABLE Temp Sense S OTS R MODE SELECT DMAX/SS COMP Error Amp NI FB + − + − Logic Cont...