Charge pump voltage inverter, -Vin output
The Analog Devices ICL7662EBA+ is a charge pump voltage converter that generates a regulated negative output voltage equal to the input voltage (-Vin), from a positive input rail. It is a fixed-output, ratiometric topology device — the output tracks the input, so a +5V supply yields -5V, and +12V yields -12V, without external inductor magnetics. Switching at 10kHz, it delivers the negative rail from a 4.5V to 20V input range, covering common 5V, 9V, 12V, and 15V system buses. The 10kHz switching frequency keeps external capacitor sizes modest — 10 µF electrolytics are typical for the flying and reservoir capacitors — while staying below the noise floor of most audio or instrumentation circuits.
Input range and output regulation
The 4.5V minimum input means the device operates from a 5V rail with headroom, and the 20V maximum input allows direct connection to a 12V or 15V supply without pre-regulation. Because the output is -Vin (fixed ratio), the negative rail tracks the positive rail — a 5V ±5% input gives a -5V ±5% output, so the downstream load sees the same tolerance as the source. No synchronous rectifier is used internally — the charge pump relies on diode steering, which sets a practical output current ceiling around 10-20 mA before the voltage drop across the diodes erodes efficiency. For loads drawing a few milliamps (op-amp negative rails, bias supplies, LCD contrast), the simple topology keeps the BOM to two capacitors and no inductor.
As an active part from Analog Devices, it is sourced through authorized distribution channels.