RT7252A/B

3

DS7252A/B-01 April 2012

www.richtek.com

©

Copyright

2012 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

Function Block Diagram

Pin No.

Pin Name

Pin Function

1

SW

Switch Node. Connect to external L-C filter.

2

VIN

Input Supply Voltage. Must bypass with a suitably large ceramic

capacitor.

3

BOOT

Bootstrap for High Side Gate Driver. Connect 0.01

μF or greater ceramic

capacitor from BOOT to SW pin.

4

EN

Chip Enable. A logic-high enables the converter; a logic-low forces the

RT7252A/B into shutdown mode, reducing the supply current to less

than 5

μA. Attach this pin to VIN with a 100kΩ pull up resistor for

automatic startup.

5

FB

Feedback Input Pin. For an adjustable output, connect an external

resistive voltage divider to this pin.

6

PGOOD

Power Good Indicator with Open Drain. The output of this pin is pulled to

low when the FB is lower than 0.7V; otherwise it is high impedance. A

100k

Ω pull-high resistor is needed.

7, 9 (Exposed Pad)

GND

Ground. The exposed pad must be soldered to a large PCB and

connected to GND for maximum power dissipation.

8

NC

No Internal Connection.

Functional Pin Description

Internal

Regulator

+

-

Enable

Comparator

EN

2.5V

5k

3V

VIN

OSC

340kHz/800kHz

Foldback

Control

+

-

1pF

35pF 400k

+

-

Error Amp

0.8V

UV Comparator

+

-

+

-

Current

Comparator

OV Comparator

0.4V

UV

FB

R

SQ

Q

+

-

0.7V

FB

BOOT

155m

SW

GND

PGOOD

Current Sense

Amplifier

Slope Comp

PGOOD

Comparator

150m

+

-

1V

OV