RT7250A/B

3

DS7250A/B-01 May 2012

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©

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

RT7250A/B into shutdown mode, reducing the supply current to less than 5

μA.

Attach this pin to VIN with a 100k

Ω 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. The output of this pin is low if the output voltage is

12.5% less than the nominal voltage. Otherwise, it is an open drain.

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