SW

BST

NC

NC

NC

NC

RTN

FB

SS

11

10

9

5

4

3

2

1

6

7

8

12

13

14

VCC

VIN

RON/SD

SGND

ISEN

SW

BST

RTN

VCC

FB

SS

VIN

10

9

8

7

6

5

4

3

2

1

RON/SD

SGND

ISEN

LM25010

SNVS419D – DECEMBER 2005 – REVISED FEBRUARY 2013

www.ti.com

Connection Diagram

Pin Descriptions

PIN NUMBER

NAME

DESCRIPTION

APPLICATION INFORMATION

WSON-10

HTSSOP-14

1

2

SW

Switching node

Internally connected to the buck switch source. Connect to

the inductor, free-wheeling diode, and bootstrap capacitor.

2

3

BST

Boost pin for bootstrap

Connect a capacitor from SW to the BST pin. The capacitor

capacitor

is charged from VCC via an internal diode during the buck

switch off-time.

3

4

ISEN

Current sense

During the buck switch off-time, the inductor current flows

through the internal sense resistor, and out of the ISEN pin

to the free-wheeling diode. The current limit comparator

keeps the buck switch off if the ISEN current exceeds 1.25A

(typical).

4

5

SGND

Current sense ground

Re-circulating current flows into this pin to the current sense

resistor.

5

6

RTN

Circuit ground

Ground return for all internal circuitry other than the current

sense resistor.

6

9

FB

Voltage feedback input from

Input to both the regulation and over-voltage comparators.

the regulated output

The FB pin regulation level is 2.5V.

7

10

SS

Softstart

An internal 11.5 µA current source charges the SS pin

capacitor to 2.5V to soft-start the reference input of the

regulation comparator.

8

11

RON/SD

On-time control and

An external resistor from VIN to the RON/SD pin sets the

shutdown

buck switch on-time. Grounding this pin shuts down the

regulator.

9

12

VCC

Output of the bias regulator

larger capacitor from VCC to ground, as close as possible to

the pins. An external voltage can be applied to this pin to

10

13

VIN

Input supply voltage

Nominal input range is 6V to 42V. Input bypass capacitors

should be located as close as possible to the VIN and RTN

pins.

1, 7, 8, 14

NC

No connection

No internal connection. Can be connected to ground plane to

improve heat dissipation.

EP

Exposed pad

Exposed metal pad on the underside of the device. It is

recommended to connect this pad to the PC board ground

plane to aid in heat dissipation.

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

2

Submit Documentation Feedback

Copyright © 2005–2013, Texas Instruments Incorporated

Product Folder Links: LM25010