ent

enb

IN UVLO

enb

R

R

V

V

R

(

)

1.23

+

=

´

EN

VIN

Voltage

Mode

Control

VOUT

GND

SS

FB

1.5 PH

2.2 PF

2.2 PF

1:

1

2

3

4, EP

5

6, 7

LMZ10504

SNVS610N – DECEMBER 2009 – REVISED SEPTEMBER 2015

www.ti.com

7 Detailed Description

7.1 Overview

The LMZ10504 SIMPLE SWITCHER power module is a complete, easy-to-use DC-DC solution capable of

driving up to a 4-A load with exceptional power conversion efficiency, output voltage accuracy, line and load

regulation. The LMZ10504 is available in an innovative package that enhances thermal performance and allows

for hand or machine soldering. The LMZ10504 is a reliable and robust solution with the following features:

lossless cycle-by-cycle peak current limit to protect for overcurrent or short-circuit fault, thermal shutdown, input

undervoltage lockout, and prebiased start-up.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Enable

The LMZ10504 features an enable (EN) pin and associated comparator to allow the user to easily sequence the

LMZ10504 from an external voltage rail, or to manually set the input UVLO threshold. The turnon or rising

threshold and hysteresis for this comparator are typically 1.23 V and 0.15 V, respectively. The precise reference

for the enable comparator allows the user to ensure that the LMZ10504 will be disabled when the system

demands it to be.

The EN pin should not be left floating. For always-on operation, connect EN to VIN.

7.3.2 Enable and UVLO

Using a resistor divider from VIN to EN as shown in the schematic diagram below, the input voltage at which the

part begins switching can be increased above the normal input UVLO level according to:

(1)

10

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