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2015-08-0011

PT0497-4

08/31/15

7

PI5PD2556/2557

Precision Adjustable

Current-Limited Power Switch

Figure 14 Switch Current Vs. Drain-Source Voltage Across

Functional Block Diagram

Figure 15

Functional Block Diagram

Functional Description

Overview

The PI5PD2556/2557 is a single-channel, current-limited power-distribution switch using N-channel MOSFETs for applications

where short circuits or heavy capacitive loads will be encountered. This device allows the user to program the current-limit

threshold between 500 mA and 5.0 A (typ) via an external resistor. This device incorporates an internal charge pump and gate

drive circuitry necessary to drive the N-channel MOSFETs. The charge pump supplies power to the driver circuit for each channel

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 PI5PD2556/2557 limits the output current to the programmed current-limit threshold

IOS during an over-current 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 the N-channel MOSFET is no longer fully enhanced.

-40°C

25°C

125°

C