RT8299

3

DS8299-01 May 2012

www.richtek.com

©

Copyright

2012 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

Function Block Diagram

Functional Pin Description

Pin No.

SOP-8

(Exposed Pad)

WDFN-10L 3x3

Pin Name

Pin Function

1

5

BOOT

Bootstrap for High Side Gate Driver. Connect a 0.1

μF or greater

ceramic capacitor from BOOT to SW pin.

2

6, 7

VIN

Supply Input Voltage. Must bypass with a suitably large ceramic

capacitor.

3

8, 9

SW

Switch Node. Connect to external LC filter.

4, 9

(Exposed Pad)

10, 11

(Exposed Pad)

GND

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

connected to GND for maximum power dissipation.

5

1

FB

Feedback Input. This pin is connected to the converter output. It

is used to regulate the output of the converter to a desired value

via an internal resistive voltage divider. For an adjustable output,

an external resistive voltage divider is connected to this pin.

6

3

EN

Enable Input. A logic high enables the converter; a logic low

forces the RT8299 into shutdown mode, reducing the supply

current to less than 3

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

up resistor for automatic startup.

7

2

PGOOD

Power Good Output. The output of this pin is open drain.

8

4

VCC

Bias Supply.

Driver

-

+

Current Sense

Amplifier

PWM

Comparator

Oscillator

500kHz

Ramp

Generator

Regulator

+

-

Error

Amplifier

SW

BOOT

FB

EN

VIN

+

-

GND

VCC

1pF

30pF

300k

OC Limit

Clamp

Reference

PGOOD

Generator

PGOOD

S Q

R Q

+

-

2V

3V

5k

Comparator