Low-Noise Positive- and Negative-Output Charge Pump With Integrated LDO

The LM27762 delivers very low-noise positive and

negative outputs that are adjustable between ±1.5V and ±5V. Input voltage range is

from 2.7V to 5.5V, and output current goes up to ±250mA. With an operating current

of only 390µA and 0.5µA typical shutdown current, the

LM27762 provides excellent performance for power amplifier and DAC bias and other

high-current, low-noise negative voltage needs. The device provides a small design

size with few external components.

Negative voltage is generated by a regulated

inverting charge pump followed by a low-noise negative LDO. The inverting charge

pump of the LM27762 device operates at 2MHz (typical) switching frequency to reduce

output resistance and voltage ripple. Positive voltage is generated from the input

by a low-noise positive LDO.

Positive and negative outputs of LM27762 have

dedicated enable inputs. These outputs support independent timing for the positive

and negative rails for specific system power-sequence needs. Enable inputs can be

also shorted together and connected to the input voltage. The LM27762 has an

optional Power-Good feature.