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PINOUT DIAGRAMS

UCC28230

UCC28231

SLUS814 – FEBRUARY 2008

TERMINAL FUNCTIONS

DFN-12

TSSOP-14

NAME

I/O

FUNCTION

PIN #

VREF is a 10-mA output reference, 1.5% accurate 5 V for UCC28230 and 3.3 V for

UCC28231. The reference voltage has short circuit protection that can be used for fixed

1

1

VREF

O

switching frequency setting and/or for housekeeping microcontroller. Place decoupling

capacitor in the range of 1

µF to 2.2 µF from this pin to GND.

The off-time control threshold pin uses a resistor divider to set current level as

2

2

OST

I

maximum value at no load condition.

3

3

OS

I

4

NC

No connection pin, TSSOP-14 only.

Oscillator timing input pin. The external resistor which is connected between this pin and

4

5

RT

I

VIN sets the oscillator frequency which varies with VIN. Tieing the external resistor to

VREF sets fixed frequency operation independent of VIN.

Input for setting the adjustable soft-start and hiccup mode. Place the soft-start capacitor

5

6

SS

I/O

capacitor value set the soft-start timing, duration of cycle-by-cycle current limit and OFF

time for hiccup mode operation.

Current sensing pin used for cycle-by-cycle current limit, short circuit protection and off

6

7

CS

time control.

8

AGND

Analog ground, TSSOP-14 only.

7

9

GND

Ground pin connected to thermal pad. All signals are referenced to this node.

0.2-A sink/source switching output pin. Connect this pin to an external driver that

8

10

O2_DIN

O

provides 1-D pulse.

0.2-A sink/source switching output pin. Connect this pin to an external driver that

9

11

O2_D

O

provides D pulse.

0.2-A sink/source switching output pin. Connect this pin to an external driver that

10

12

O1_DIN

O

provides 1-D pulse.

0.2-A sink/source switching output pin. Connect this pin to an external driver that

11

13

O1_D

O

provides D pulse.

Connect this pin to a 7-V to 17-V bias supply. Place a high quality at least 1-

µF ceramic

12

14

VDD

I

bypass capacitor from this pin to GND.

Copyright © 2008, Texas Instruments Incorporated

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Product Folder Link(s): UCC28230 UCC28231