LP38856 datasheet(10/24 Pages) TI

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LP38856-x.x

GND

OUT

BIAS

Under-Voltage

Lock-Out

Thermal

Shut Down

1.2V

Enable

VREF

0.6V

ILIMIT

rEN

LP38856

SNVS336F – JUNE 2006 – REVISED AUGUST 2015

www.ti.com

7 Detailed Description

7.1 Overview

The LP38556 is a fast-response, high-current, low-dropout regulator, available in output voltages 0.8 V and 1.2

V. This device is capable of delivering 3-A continuous load current. Standard regulator features, such as

overcurrent and overtemperature protection, are also included.

The LP38556 contains several features:

•

Low dropout voltage, typical 240 mV at 3-A load.

•

Low GND pin current, typical 10 mA at 3-A load.

•

A shutdown feature is available, allowing the regulator to consume only 1 µA when EN pin is low.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Enable Operation

The enable pin (EN) provides a mechanism to enable, or disable, the regulator output stage. The EN pin has an

internal pullup, through a typical 180-k

Ω resistor, to VBIAS.

If the EN pin is actively driven, pulling the EN pin above the VEN threshold of 1.25 V (typical) will turn the

regulator output on, while pulling the EN pin below the VEN threshold will turn the regulator output off. There is

approximately 100 mV of hysteresis built into the enable threshold provide noise immunity.

If the enable function is not needed, the EN pin must be left open, or connected directly to VBIAS. If the EN pin is

left open, stray capacitance on this pin must be minimized, otherwise the output turnon will be delayed while the

stray capacitance is charged through the internal resistance (rEN).

7.3.2 Input Voltage

The input voltage (VIN) is the high current external voltage rail that will be regulated down to a lower voltage,

which is applied to the load. The input voltage must be at least VOUT + VDO, and no higher than whatever value is

used for VBIAS.

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