3

1

2

8

7

6

5

4

OSCILLATOR

S

Q

R

RC

1.2R

R

0.5 V

PEAK CURRENT

COMPARATOR

Q

Q

T

S

Q

R

S

Q

R

VDD

VOLTAGE

REFERENCE

14 V

PWM

COMPARATOR

PWM

LATCH

SOFT START

0.5 V

VDD–1 V

0.75 V

2.2 V

2.0 V

FB

COMP

CS

VDD

OUTA

OUTB

GND

SLOPE = 1 V/ms

VDD OK

OVERCURRENT

COMPARATOR

22 k Ω

UCC2808-1, UCC2808-2, UCC3808-1, UCC3808-2

www.ti.com

SLUS168E – APR 1999 – REVISED AUGUST 2015

7 Detailed Description

7.1 Overview

The UCCx808-x device is a highly-integrated, low power current mode push-pull PWM controller. The controller

employs low starting current, and employs an internal control algorithm that offers accurate static output voltage

regulation against line and load. The UCCx808-x family offers a variety of package temperature range options,

and choice of undervoltage lockout levels. The family has UVLO thresholds and hysteresis options for offline and

battery-powered system.

Table 1. Undervoltage Lockout Levels

PART NUMBER

TURN ON THRESHOLD

TURN OFF THRESHOLD

UCCx808-1

12.5 V

8.3 V

UCCx808-2

4.3 V

4.1 V

Table 2. Undervoltage Lockout Options

PACKAGED DEVICES

UVLO OPTION

SOIC (D)

PDIP (N)

12.5 V/8.3 V

UCC2808D-1

UCC2808N-1

–40°C to 85°C

4.3 V/4.1 V

UCC2808D-2

UCC2808N-2

12.5 V/8.3 V

UCC3808D-1

UCC3808N-1

0°C to 70°C

4.3 V/4.1 V

UCC3808D-2

UCC3808N-2

7.2 Functional Block Diagram

Pinout shown is for SOIC and PDIP packages.

Figure 4. Functional Block Diagram

Copyright © 1999–2015, Texas Instruments Incorporated

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Product Folder Links: UCC2808-1 UCC2808-2 UCC3808-1 UCC3808-2