PAD

2

6

3

4

5

1

7

16

15

17

18

19

20

21

PVIN

SW

SW

SW

SW

PVIN

PGND

FREQ

EN

AGND

AGND

AGND

AGND

2V5

LM21305

SNVS639F – DECEMBER 2009 – REVISED MARCH 2013

www.ti.com

DESCRIPTION (CONTINUED)

The LM21305 offers flexible system configuration with programmable switching frequency from 300 kHz to 1.5

MHz using one resistor or via external clock synchronization. On-chip bias supply sub-regulators alleviate the

need for external bias power and simplify PCB layout. The device also offers internal soft-start to limit inrush

current, pre-biased and monotonic startup capability, cycle-by-cycle current limiting, and thermal shutdown. Peak

current-mode control with a high-gain error amplifier maintains stability throughout the entire input voltage and

load current ranges and enables excellent line and load transient response.

Offered in a thermally enhanced WQFN-28 package, the LM21305 features internal output over-voltage and

over-current protection circuits for increased system reliability. A precision enable pin and integrated input UVLO

allow the turn-on of the device to be tightly controlled and sequenced. An integrated open-drain power good

indicator provides power rail sequencing capability and fault indication.

Connection Diagram

Figure 1. WQFN-28 Package, Exposed Pad

Package Number RSG

2

Submit Documentation Feedback

Copyright © 2009–2013, Texas Instruments Incorporated

Product Folder Links: LM21305