LM34914

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SNVS453A – MAY 2007 – REVISED DECEMBER 2007

Pin Descriptions (continued)

Pin Number

Name

Description

Application Information

5

RTN

Circuit Ground

Ground for all internal circuitry other than the current limit

detection.

6

FB

Feedback input from the regulated

Internally connected to the regulation and over-voltage

output

comparators. The regulation level is 2.5V.

7

SS

Softstart

An internal current source charges an external capacitor to

2.5V, providing the softstart function.

8

RON/SD

On-time control and shutdown

An external resistor from VIN to this pin sets the buck switch

on-time. Grounding this pin shuts down the regulator.

9

Output from the startup regulator

Nominally regulated at 7.0V. Connect a 0.1 µF capacitor from

this pin to RTN. An external voltage (8V to 14V) can be

applied to this pin to reduce internal dissipation. An internal

diode connects VCC to VIN.

10

VIN

Input supply voltage

Operating input range is 8.0V to 40V.

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.

Absolute Maximum Ratings

(1)

VIN to RTN

44V

BST to RTN

52V

SW to RTN (Steady State)

-1.5V

BST to VCC

44V

VIN to SW

44V

BST to SW

14V

VCC to RTN

14V

SGND to RTN

-0.3V to +0.3V

Current out of ISEN

See text

SS to RTN

-0.3V to 4V

All Other Inputs to RTN

-0.3 to 7V

Human Body Model

2kV

Storage Temperature Range

-65°C to +150°C

JunctionTemperature

150°C

(1)

Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which

operation of the device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.

(2)

The human body model is a 100pF capacitor discharged through a 1.5k

Ω resistor into each pin.

Operating Ratings

(1)

VIN Voltage

8.0V to 40V

Junction Temperature

−40°C to + 125°C

(1)

Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which

operation of the device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Copyright © 2007, Texas Instruments Incorporated

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