RT2856

2

DS2856-10

October 2016

www.richtek.com

©

Copyright

2016 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

Functional Pin Description

Pin No.

Pin Name

Pin Function

1

RT/SYNC

Oscillator Resistor and External Frequency Synchronization Input. Connecting a

resistor from this pin to GND sets the switching frequency or connecting an

external clock to this pin changes the switching frequency.

2, 3,

15 (Exposed Pad)

GND

System Ground. Provide the ground return path for the control circuitry and

low-side power MOSFET. The exposed pad must be soldered to a large PCB

and connected to GND for minimum power dissipation.

4, 5

PVIN

Power Input. Supplies the power switches of the device.

6

VIN

Supply Voltage Input. Supplies the control circuitry and internal reference of the

device.

7

FB

Feedback Voltage Input. This pin is used to set the desired output voltage via an

external resistive divider. The feedback reference voltage is 0.8V typically.

8

COMP

Compensation Node. The current comparator threshold increases with this

control voltage. Connect external compensation elements to this pin to stabilize

the control loop.

9

SS/TR

Soft-Start and Tracking Control Input. Connect a capacitor from SS to GND to

set the soft-start period. The soft-start period can be used to track and sequence

when the external voltage on this pin overrides the internal reference.

10

EN

Enable Control Input. Floating this pin or connecting this pin to logic high can

enable the device and connecting this pin to GND can disable the device.

11, 12

LX

Switch Node. LX is the switching node that supplies power to the output and

connect the output LC filter from LX to the output load.

13

BOOT

Bootstrap Supply for High-Side Gate Driver. Connect a 100nF or greater

capacitor from LX to BOOT to power the high-side switch.

14

PGOOD

Power Good Indicator Output. This pin is an open-drain logic output that is pulled

to ground when the output voltage is lower or higher than its specified threshold

under the conditions of OVP, OTP, dropout, EN shutdown, or during slow start.

Ordering Information

Note :

Richtek products are :

ments of IPC/JEDEC J-STD-020.

Pin Configurations

(TOP VIEW)

WQFN-14AL 3.5x3.5

Package Type

QW : WQFN-14AL 3.5x3.5 (W-Type)

RT2856

Lead Plating System

G : Green (Halogen Free and Pb Free)

GND

GND

PVIN

PVIN

VIN

BOOT

LX

EN

SS/TR

LX

2

4

3

9

13

10

11

12

6

5

8

7

14

1

GND

15