D3

D2

D1

C3

C1

B3

B1

A3

A2

A1

SW

RTN

BST

VCC

SS

FB

VIN

ISEN

SGND

RON/SD

D1

D2

D3

C1

C3

B1

B3

A1

A2

A3

LM34919B

LM34919B-Q1

SNVS623B – MAY 2010 – REVISED JULY 2013

www.ti.com

Connection Diagram

Figure 1. Bump Side

Figure 2. Top View

Pin Descriptions

Pin No.

Name

Description

Application Information

A1

RON/SD

On-time control and

An external resistor from VIN to this pin sets the buck switch on-time.

shutdown

Grounding this pin shuts down the regulator.

A2

RTN

Circuit Ground

Ground for all internal circuitry other than the current limit detection.

A3

FB

Feedback input from

Internally connected to the regulation and over-voltage comparators. The

the regulated output

regulation level is 2.5V.

B1

SGND

Sense Ground

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

B3

SS

Softstart

An internal current source charges an external capacitor to 2.5V, providing the

softstart function.

C1

ISEN

Current sense

The re-circulating current flows through the internal sense resistor, and out of

this pin to the free-wheeling diode. Current limit is nominally set at 0.64A.

C3

VCC

Output from the startup Nominally regulated at 7.0V. An external voltage (7V-14V) can be applied to

regulator

this pin to reduce internal dissipation. An internal diode connects VCC to VIN.

D1

VIN

Input supply voltage

Nominal input range is 6.0V to 40V.

D2

SW

Switching Node

Internally connected to the buck switch source. Connect to the inductor, free-

wheeling diode, and bootstrap capacitor.

D3

BST

Boost pin for bootstrap

Connect a 0.022 µF capacitor from SW to this pin. The capacitor is charged

capacitor

from VCC via an internal diode during each off-time.

This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with

appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.

ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more

susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.

2

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