Overview: MC1121 100mA Charge Pump Voltage Converter with Shutdown
The MC1121 is a charge pump converter with 100mA 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 MC1121 uses no inductors saving cost, size, and reducing EMI. An on–board oscillator operates at a typical frequency of 10kHz (at VDD = 5V) when the frequency control input (FC) is connected to ground. The oscillator frequency increases to 200kHz when FC is connected to VDD, allowing the use of smaller capacitors. Operation at sub–10kHz frequencies results in lower quiescent current and is acplished with the addition of an external capacitor from OSC (pin 7) to ground. The MC1121 can be driven from an external clock connected OSC. Typical supply current at 10kHz is 50µA, and falls to less than 1µA when the shutdown input is brought low, whether the internal or an external clock is used. The MC1121 is available in a Micro–8 package.
