TC1121

The TC1121 is a charge pump converter with 100 mA output current capability. It converts a 2.4V to 5.5V input to a corresponding negative output voltage. As with all charge pump converters, the TC1121 uses no inductors saving cost, size and EMI.

An on-board oscillator operates at a typical frequency of 10 kHz (at V+ = 5V) when the frequency control input (FC) is connected to ground. The oscillator frequency increases to 200 kHz when FC is connected to V+, allowing the use of smaller capacitors. Operation at sub-10 kHz frequencies results in lower quiescent NScurrent and is accomplished with the addition of an external capacitor from OSC (pin 7) to ground. The TC1121 also can be driven from an external clock NSconnected OSC. Typical supply current at 10 kHz is 50 A, and falls to less than 1 A when the shutdown input is brought low, whether the internal or an external clock is used. The TC1121 is available in 8-pin SOIC, MSOP and PDIP packages.