FB

VIN

VCC

REGULATOR

DRIVER

HB

ADAPTIVE

TIMER

EN

UVLO

UVLO

ERROR

AMP

DIS

COMP

CLK

S

R

Q

Q

OSCILLATOR

AGND

CLK

CSG

RAMP GENERATOR

+

SLEEP

MODE

SHUTDOWN

PWM

CURRENT

LIMIT

RAMP

SS

VIN

5 PA

1V

10 PA

CS

DRIVER

PGND

LO

VOUT

HO

SW

1

2

3

4

5

14

6

15

10

13

12

20

19

18

+

-

4.5V

17

HICCUP FAULT TIMER

256 CLOCK CYCLES

UVLO

LOGIC

STANDBY

UVLO

7

8

9

16

VCCX

A =10

VCC

DEMB

11

TRACK

SAMPLE

and

HOLD

CLK

DIODE

EMULATION

CONTROL

SS

SW

THERMAL

SHUTDOWN

3V

VCCX

EN

SYNC

1.215 V

1

0.5V

Q2

Q1

L1

D1

RT/SYNC

1.215V

7. 4 V

LM25116

D2

( VIN - VOUT ) + 25 PA

V x

/

.6V

6V - 42V

LM25116

www.ti.com

SNVS509C – APRIL 2007 – REVISED AUGUST 2011

BLOCK DIAGRAM AND TYPICAL APPLICATION CIRCUIT

Figure 2. Typical Application Circuit

DETAILED OPERATING DESCRIPTION

The LM25116 high voltage switching regulator features all of the functions necessary to implement an efficient

high voltage buck regulator using a minimum of external components. This easy to use regulator integrates high-

side and low-side MOSFET drivers capable of supplying peak currents of 2 Amps. The regulator control method

is based on current mode control utilizing an emulated current ramp. Emulated peak current mode control

provides inherent line feed-forward, cycle by cycle current limiting and ease of loop compensation. The use of an

emulated control ramp reduces noise sensitivity of the pulse-width modulation circuit, allowing reliable processing

of the very small duty cycles necessary in high input voltage applications. The operating frequency is user

programmable from 50 kHz to 1 MHz. An oscillator/synchronization pin allows the operating frequency to be set

by a single resistor or synchronized to an external clock. Fault protection features include current limiting, thermal

shutdown and remote shutdown capability. An under-voltage lockout input allows regulator shutdown when the

input voltage is below a user selected threshold, and an enable function will put the regulator into an extremely

low current shutdown via the enable input. The TSSOP-20EP package features an exposed pad to aid in thermal

dissipation.

Copyright © 2007–2011, Texas Instruments Incorporated

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