9

TPS25221

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SLVSDT3 – JANUARY 2018

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9 Detailed Description

9.1 Overview

The TPS25221 is current-limited, power-distribution switch using N-channel MOSFETs for applications where

short circuits or heavy capacitive loads are encountered. The TPS25221 has an adjustable current limit up to 2.7

A.

This device incorporates an internal charge pump and the gate drive circuitry necessary to drive the N-channel

MOSFET. The charge pump supplies power to the driver circuit and provides the necessary voltage to pull the

gate of the MOSFET above the source. The charge pump operates from input voltages as low as 2.5 V and

requires little supply current. The driver controls the gate voltage of the power switch. The driver incorporates

circuitry that controls the rise and fall times of the output voltage to limit large current and voltage surges and

provides built-in soft-start functionality.

The TPS25221 limits the output current to the current-limit threshold (set by external resistor for TPS25221) IOS

during an overcurrent or short-circuit event by reducing the charge pump voltage driving the N-channel MOSFET

and operating it in the linear range of operation. The result of limiting the output current to IOS reduces the

output voltage at OUT because N-channel MOSFET is no longer fully enhanced.

9.2 Functional Block Diagram