Charge pump with 100 mA output and selectable frequency
The Maxim Integrated MAX660CSA+T is a charge-pump DC-DC converter that delivers a fixed output of either -Vin (inverting) or 2Vin (doubling) from a single input between 1.5 V and 5.5 V. It is rated for 100 mA output current and operates at a user-selectable switching frequency of 10 kHz or 80 kHz, letting you trade capacitor size against switching noise.
What the 100 mA rating and 1.5 V minimum input mean for the BOM
The 100 mA output current sets the load budget: if your downstream rail needs more than that, you step up to a higher-current charge pump or a switching regulator. The 1.5 V minimum input means the part can run from a single alkaline cell (nominal 1.5 V) or a Li-ion cell (3.0–4.2 V) down to its end-of-discharge voltage. The 5.5 V maximum input covers standard 5 V logic rails with margin. The two switching frequencies let you use smaller ceramic capacitors at 80 kHz (lower ripple) or larger, cheaper electrolytics at 10 kHz if noise is less critical.