14-SOIC charge pump for negative rail generation
The ICL7662CBD+T is a charge pump DC-DC converter from Analog Devices that generates a negative output voltage equal to -Vin from a positive input rail between 4.5 V and 20 V.
The 10 kHz switching frequency is fixed and unsynchronized — the output ripple sits at this fundamental and its harmonics, so the downstream LDO or filter must attenuate the 10 kHz band. With no synchronous rectifier (: No), the output diode drop adds to the voltage loss; the effective output voltage is -Vin minus two Schottky drops in a typical two-diode charge pump. Ratiometric function means the output tracks the input proportionally — a 5 V input yields approximately -5 V out, and a 12 V input yields approximately -12 V out, within the charge pump's load capability.