ADM660ARZ (ANALOG DEVICES)

The ADM660ARZ is a CMOS Switched-capacitor Voltage Converter that can be used to either invert the input supply voltage giving VOUT = -VIN or double it giving VOUT = 2VIN. This inverting scheme is ideal for generating a negative rail in single power supply systems. Only two small external capacitors are needed for the charge pump. Output currents up to 50mA with greater than 90% efficiency are achievable, while 100mA achieves greater than 80% efficiency. A frequency control (FC) input pin is used to select either 25 or 120kHz charge-pump operation. This is used to optimize capacitor size and quiescent current. With 25kHz selected, a 10µF external capacitor is suitable, while with 120kHz the capacitor may be reduced to 2.2µF. The oscillator frequency can also be controlled with an external capacitor connected to the OSC input or by driving this input with an external clock.