+

+

+

+

BST

RON

RTN

SW

VCC

FB

UVLO

VIN

VOUT1

VOUT2

D1

X1

LM34925

+

D2

7.5V-100V

1

2

3

4

5

6

8

7

Product

Folder

Sample &

Buy

Technical

Documents

Tools &

Software

Support &

Community

Reference

Design

LM34925

SNVS846F – JUNE 2012 – REVISED NOVEMBER 2014

LM34925 Integrated Secondary-Side Bias Regulator for Isolated DC-DC Converters

1 Features

3 Description

The LM34925 regulator features all of the functions

1

•

Wide 7.5-V to 100-V Input Range

needed to implement a low cost, efficient, isolated

•

Integrated 100-mA High-Side,

bias regulator. This high voltage regulator contains

and Low-Side Switches

two 100-V N-Channel MOSFET switches: a high-side

•

No Schottky Required

buck switch and a low-side synchronous switch. The

constant-on-time (COT) control scheme employed in

•

Constant On-Time Control

the LM34925 device requires no loop compensation

•

No Loop Compensation Required

and

provides

excellent

transient

response.

The

•

Ultra-Fast Transient Response

regulator operates with an on-time that is inversely

proportional to the input voltage. This feature allows

•

Nearly Constant Operating Frequency

the operating frequency to remain relatively constant.

•

Intelligent Peak Current Limit

An intelligent peak current limit is implemented with

•

Adjustable Output Voltage From 1.225 V

integrated sense circuit. Other features include a

•

Precision 2% Feedback Reference

programmable input under voltage comparator to

inhibit

operation

during

low-voltage

conditions.

•

Frequency Adjustable to 1 MHz

Protection features include thermal shutdown and

•

Adjustable Undervoltage Lockout (UVLO)

•

Remote Shutdown

device

is

offered

in

8-pin

WSON

and

8-pin SO PowerPAD plastic packages.

•

Thermal Shutdown

•

Packages:

Device Information(1)

–

8-Pin WSON

PART NUMBER

PACKAGE

BODY SIZE (NOM)

–

8-Pin SO PowerPAD™

SO PowerPAD (8)

4.89 mm × 3.90 mm

LM34925

WSON (8)

4.00 mm × 4.00 mm

2 Applications

(1) For all available packages, see the orderable addendum at

•

Isolated Telecom Bias Supply

the end of the data sheet.

•

Isolated Automotive and Industrial Electronics

Typical Application Schematic

1

An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.