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SLUS456D − APRIL 1999 - REVISED AUGUST 2002

www.ti.com

D Dual Output Drive Stages in Push-Pull

Configuration

D Current Sense Discharge Transistor to

Improve Dynamic Response

D 130-µA Typical Starting Current

D 1-mA Typical Run Current

D Operation to 1 MHz

D Internal Soft Start

D On-Chip Error Amplifier With 2-MHz Gain

Bandwidth Product

D On Chip VDD Clamping

D Output Drive Stages Capable of 500-mA

Peak-Source Current, 1-A Peak-Sink Current

description

The UCC3808A is a family of BiCMOS push-pull, high-speed, low-power, pulse-width modulators. The UCC3808A

contains all of the control and drive circuitry required for off-line or dc-to-dc fixed frequency current-mode switching

power supplies with minimal external parts count.

The UCC3808A dual output drive stages are arranged in a push-pull configuration. Both outputs switch at half the

oscillator frequency using a toggle flip-flop. The dead time between the two outputs is typically 60 ns to 200 ns

depending on the values of the timing capacitor and resistors, thus limiting each output stage duty cycle to less than

50%.

block diagram

UDG-00097

Note: Pinout shown is for SOIC and PDIP packages. TSSOP pinout is different.

312

OSCILLATOR

1.2R

0.5 V

PEAK CURRENT

COMPARATOR

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

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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

COMP

VDD

OUTA

OUTB

GND

D OR N PACKAGE

(TOP VIEW)

OUTA

VDD

COMP

OUTB

GND

PW PACKAGE

(TOP VIEW)

Summary of content (13 pages)

PAGE 1
SLUS456D − APRIL 1999 - REVISED AUGUST 2002 D Dual Output Drive Stages in Push-Pull D D D D D D D D D OR N PACKAGE (TOP VIEW) Configuration Current Sense Discharge Transistor to Improve Dynamic Response 130-µA Typical Starting Current 1-mA Typical Run Current Operation to 1 MHz Internal Soft Start On-Chip Error Amplifier With 2-MHz Gain Bandwidth Product On Chip VDD Clamping Output Drive Stages Capable of 500-mA Peak-Source Cur
PAGE 2
SLUS456D − APRIL 1999 - REVISED AUGUST 2002 description (continued) The UCC3808A family offers a variety of package options, temperature range options, and choice of undervoltage lockout levels. The family has UVLO thresholds and hysteresis options for off-line and battery powered systems. Thresholds are shown in the table below. The UCC3808A is an enhanced version of the UCC3808 family.
PAGE 3
SLUS456D − APRIL 1999 - REVISED AUGUST 2002 electrical characteristics, TA = 0°C to 70°C for the UCC3808A-x, −40°C to 85°C for the UCC2808A-x, VDD = 10 V (see Note 6), 1-µF capacitor from VDD to GND, R = 22 kΩ, C = 330 pF TA = TJ, (unless otherwise noted) Error Amplifier Section Input voltage COMP = 2 V 1.95 Input bias current 2 –1 Open loop voltage gain COMP sink current FB = 2.
PAGE 4
SLUS456D − APRIL 1999 - REVISED AUGUST 2002 pin assignments COMP: COMP is the output of the error amplifier and the input of the PWM comparator. The error amplifier in the UCC3808A is a true low-output impedance, 2-MHz operational amplifier. As such, the COMP pin can both source and sink current. However, the error amplifier is internally current limited, so that zero duty cycle can be externally forced by pulling COMP to GND.
PAGE 5
SLUS456D − APRIL 1999 - REVISED AUGUST 2002 pin assignments (continued) RC 4 FREQUENCY = VDD 2 S RC (APPROXIMATE FREQUENCY) Q R 1.41 OSCILLATOR OUTPUT 0.2 V UDG-00095 Figure 1. Block Diagram for Oscillator NOTE A: The oscillator generates a sawtooth waveform on RC. During the RC rise time, the output stages alternate on time, but both stages are off during the RC fall time.
PAGE 6
− VIN 36 V TO 72 V + 10 µF 4700 µF www.ti.com 2.80 kΩ 0.1 µF 0.47 µF 86.6 kΩ 330 pF 2 kΩ 2.2 Ω 51 kΩ 1/4 W CURRENT SENSE 0.2 Ω 2K12907 IRF640 BYV 28−200 1000 pF 6 2 CS 3 UCC3808AD−1 7 2.2 Ω 330 pF 20 kΩ 432 Ω 4.99 kΩ RC PRIMARY GROUND 4.99 kΩ RC 4 5 OUTA OUTB GND 62 Ω COMP FB 1 8 VDD 62 Ω 20 kΩ BYV 28−200 IRF640 1000 pF 1 mH 10 Ω 12 NP1 NP2 2 1 6 H11A1 U3 3 240 Ω 0.01 µF 1 kV EF25 7µH 5 4 DF02SGICT NS2 NS1 32CTQ030 0.1 µF ER28 8:2 0.
PAGE 7
SLUS456D − APRIL 1999 - REVISED AUGUST 2002 TYPICAL CHARACTERISTICS IDD vs OSCILLATOR FREQUENCY OSCILLATOR FREQUENCY vs EXTERNAL RC VALUES COMP TO CS OFFSET vs TEMPERATURE 14 1000 1.2 C = 100 pF 12 VDD = 10 V, t = 25 5C 1.0 C = 330 pF 100 C = 1000 pF 10 8 6 C = 820 pF 4 C = 560 pF IDD without load 2 50 100 150 0.6 0.
PAGE 8
PACKAGE OPTION ADDENDUM www.ti.
PAGE 9
PACKAGE OPTION ADDENDUM www.ti.
PAGE 10
PACKAGE OPTION ADDENDUM www.ti.com 10-Jun-2014 PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details.
PAGE 11
PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 TAPE AND REEL INFORMATION *All dimensions are nominal Device UCC2808ADTR-1 Package Package Pins Type Drawing SOIC SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1 UCC2808ADTR-2 SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1 UCC2808APWTR-1 TSSOP PW 8 2000 330.0 12.4 7.0 3.6 1.6 8.0 12.
PAGE 12
PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) UCC2808ADTR-1 SOIC D 8 2500 340.5 338.1 20.6 UCC2808ADTR-2 SOIC D 8 2500 340.5 338.1 20.6 UCC2808APWTR-1 TSSOP PW 8 2000 367.0 367.0 35.0 UCC2808APWTR-2 TSSOP PW 8 2000 367.0 367.0 35.0 UCC3808ADTR-1 SOIC D 8 2500 340.5 338.1 20.6 UCC3808ADTR-2 SOIC D 8 2500 340.5 338.1 20.
PAGE 13
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.