FB

SW

RTN

ON TIMER

DRIVER

BST

LEVEL

SHIFT

SD/

2.5V

THERMAL

SHUTDOWN

0.725A

BUCK

SWITCH

CURRENT

SENSE

COMPLETE

START

COMPLETE

START

Ron

100 PH

L1

C2

15 PF

R3

3.01k

R4

1k

R2

100k

200k

C4

0.01 PF

C3

0.1 PF

12V -42V

10V

LM25007

UVLO

FB

R5

1

UVLO

REGULATION

COMPARATOR

OVER-VOLTAGE

COMPARATOR

2.875V

SD

SD

COMPLETE

START

MINIMUM OFF

TIMER

C1

1 PF

8

6

5

3

4

1

2

7

7V SERIES

REGULATOR

CURRENT LIMIT

OFF TIMER

SHUTDOWN

C5

0.1 PF,

100V

D1

Q

CLR

Q

SET

S

R

+

-

+

-

+

-

LM25007

www.ti.com

SNVS401C – JANUARY 2006 – REVISED FEBRUARY 2013

Pin Descriptions

Pin

Name

Description

Application Information

1

SW

Switching Node

Power switching node. Connect to the inductor, bootstrap capacitor, and free-wheeling

diode.

2

BST

Boost Boot–strap

An external capacitor is required between the BST and the SW pins. A 0.01µF ceramic

capacitor input

capacitor is recommended.

3

RCL

Current Limit OFF time

A resistor between this pin and RTN sets the off-time when current limit is detected.

programming pin

The off-time is preset to 17 µs if FB = 0V .

4

RTN

Circuit Ground

5

FB

Feedback Signal from

This pin is connected to the inverting input of the internal regulation comparator. The

Regulated Output

regulation threshold is 2.5V.

6

RON/SD

On-time set pin

A resistor between this pin and VIN sets the switch on-time as a function of Vin. The

minimum recommended on-time is 300ns at the maximum input voltage.

7

VCC

Output from the internal

If an auxiliary voltage is available to raise the voltage on this pin above the regulation

high voltage bias

setpoint (7V), the internal series pass regulator will shutdown, reducing the IC power

regulator.

dissipation. Do not exceed 14V. This output provides gate drive power for the internal

Buck switch. An internal diode is provided between this pin and the BST pin. A local

0.1uF decoupling capacitor is recommended.

8

VIN

Input supply voltage

Recommended operating range: 9V to 42V.

-

EP

Exposed pad, underside

Exposed metal pad on the WSON package underside. It is recommended to connect

of the WSON package

this pad to the PC board ground plane to aid in heat dissipation.

option

Typical Application Circuit and Block Diagram

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