Charge pump for small negative or doubled rails
The Analog Devices MAX1853EXT+T is a ratiometric charge pump IC that generates either a negative output equal to -Vin or a doubled positive output of 2Vin from a single 2.5 V to 5.5 V input. It delivers up to 30 mA at a fixed switching frequency of 200 kHz. Typical applications include generating a small negative bias rail for op-amps, LCD contrast supplies, or a low-current boosted rail in battery-powered portable gear.
30 mA output — sizing the load budget
The 30 mA output current limit is the hard ceiling for this charge pump. It suits small-signal rails — a single op-amp bias, a level-shifter supply, or an LCD contrast driver — not a main power rail. If your load draws more than 30 mA peak, this part will drop out of regulation. The fixed 200 kHz switching frequency means the output ripple spectrum is predictable; plan for a ceramic output capacitor sized for that frequency.
Input range and output configuration
The output is ratiometric, not regulated — it tracks the input as either -Vin or 2Vin.