Datasheet

D1D2D3

C1C3

B1B3

A1A2A3

D3D2D1

C3C1

B3B1

A3A2A1

RTN

BST

VCC

VIN

ISEN

SGND

RON/SD

LM34919

SNOSAY2E –MAY 2007–REVISED FEBRUARY 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 the Internally connected to the regulation and over-voltage comparators. 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 regulates 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 8.0V 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 V

via an internal diode during each off-time.

Product Folder Links: LM34919