AAT3190 datasheet(8/16 Pages) ANALOGICTECH

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AAT3190

Positive/Negative Charge Pump for Voltage Bias

3190.2005.03.1.0

Functional Block Diagram

Control

UVLO

Band

Gap

Ref.

Reference

Oscillator

Over-

Temperature

Protection

DRVP

DRVN

FBP

REF

FBN

GND

Functional Description

Dual Charge Pump Regulators

The AAT3190 provides low-power regulated output

voltages from two individual charge pumps. Using

a single stage, the first charge pump inverts the

supply voltage (V

IN) and provides a regulated neg-

ative output voltage. The second charge pump dou-

bles V

IN and provides a regulated positive output

voltage. These outputs use external Schottky

diodes and capacitor multiplier stages (as many as

required) to regulate up to ±25V. A constant switch-

ing frequency of 1MHz minimizes the output ripple

and capacitor size.

Negative Charge Pump

During the first half-cycle, the P-channel MOSFET

turns on and the flying capacitor C7 charges to V

minus a diode drop (Figure 1). During the second

half-cycle, the P-channel MOSFET turns off and

the N-channel MOSFET turns on, level shifting C7.

This connects C7 in parallel with the output reser-

voir capacitor C10.

If the voltage across C10

minus a diode drop is less than the voltage across

C7, current flows from C7 to C10 until the diode

turns off.

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