FB

SW

RTN

BST

1.225V

VILIM

LM25019

ILIM

COMPARATOR

+

-

V UVLO

ON/OFF

TIMERS

COT CONTROL

LOGIC

1.225V

START-UP

REGULATOR

FEEDBACK

DISABLE

THERMAL

SHUTDOWN

UVLO

OVER-VOLTAGE

1.62V

UVLO

4.5V

SD

SHUTDOWN

VDD REG

BG REF

0.66V

20 µA

CURRENT

LIMIT

ONE-SHOT

LM25019

SNVS952D – DECEMBER 2012 – REVISED DECEMBER 2014

www.ti.com

7 Detailed Description

7.1 Overview

The LM25019 step-down switching regulator features all the functions needed to implement a low-cost, efficient,

buck converter that can supply up to 100 mA to the load. This high-voltage regulator contains 48 V, N-channel

buck and synchronous switches, is easy to implement, and is provided in thermally enhanced SO PowerPAD-8

and WSON-8 packages. The regulator operation is based on a constant on-time control scheme using an on-

while providing minimum foldback. The simplified block diagram of the LM25019 device is shown in Figure 10.

The LM25019 device can be applied in numerous applications to efficiently regulate down higher voltages. This

regulator is well suited for 12-V and 24-V rails. Protection features include: thermal shutdown, undervoltage

lockout, minimum forced off-time, and an intelligent current limit.

7.2 Functional Block Diagram

Figure 10. Functional Block Diagram

8

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