Datasheet

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UCC25705, UCC25706, UCC35705, UCC35706

HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR

SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010

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D Greater Than 4-MHz Operation

D Integrated Oscillator / Voltage Feed Forward

Compensation

D >4:1 Input Voltage Range

D 25-ns Current Limit Delay

D Programmable Maximum Duty Cycle Clamp

D Optocoupler Interface

D 50-μA Start-Up Current

D 4.2-mA Operating Current @ 1 MHz

D Smallest Footprint of the 8-pin MSOP

Package Minimizes Board Area and Height

description

The UCC35705 and UCC35706 devices are 8-pin voltage mode primary side c ontrollers with fast over-current

protection. These devices are used as core high-speed building blocks in high performance isolated and non-isolated

power converters.

UCC35705/UCC35706 devices feature a high speed oscillator with integrated feed-forward compensation for

improved converter performance. A typical current sense to output delay time of 25 ns provides fast response to

overload conditions. The IC also provides an accurate programmable maximum duty cycle clamp for increased

protection which can also be disabled for the oscillator to run at maximum possible duty cycle.

Two UVLO options are offered. The UCC35705 with lower turn-on voltage is intended for dc-to-dc converters while

the higher turn-on voltage and the wider UVLO range of the UCC35706 is better s uited for offline applications.

The UCC35705/UCC35706 family is offered in 8-pin MSOP (DGK), SOIC (D) and PDIP (P) packages.

typical application schematic

UDG-99181

VDD

OUT

GND

ILIM

VFF

DISCH

UCC35705/6

OUT

SOFT

START

CIRCUIT

TPS2829

FB 2

MODE = 1

FET DRIVER

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

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

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

ILIM

VFF

DISCH

VDD

OUT

GND

D, OR P PACKAGE

(TOP VIEW)

ILIM

VFF

DISCH

VDD

OUT

GND

DGK PACKAGE

(TOP VIEW)

Summary of content (22 pages)

PAGE 1
UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 D Greater Than 4-MHz Operation D Integrated Oscillator / Voltage Feed Forward D D D D D D D Compensation >4:1 Input Voltage Range 25-ns Current Limit Delay Programmable Maximum Duty Cycle Clamp Optocoupler Interface 50-μA Start-Up Current 4.
PAGE 2
UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 absolute maximum ratings over operating free-air temperature (unless otherwise noted)†} Supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 V Input voltage (VFF,RC,ILIM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 electrical characteristics, VDD = 11 V, VIN = 30 V, RT = 47 k, RDISCH = 400 k, RFF = 14 k, CT = 220 pF, CVDD = 0.1 μF, and no load on the outputs, 0°C ≤ TA ≤ 70°C for the UCC3570x and --40°C ≤ TA ≤ 85°C for the UCC2570x, TA = TJ, (unless otherwise specified) line sense section PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Low line comparator threshold 0.95 1.00 1.
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UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 pin descriptions DISCH: A resistor to VIN sets the oscillator discharge current programming a maximum duty cycle. When grounded, an internal comparator switches the oscillator to a quick discharge mode. A small 100-pF capacitor between DISCH and GND may reduce oscillator jitter without impacting feed-forward performance.
PAGE 5
UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 pin descriptions (continued) 50 mV DISCH 4 -+ MODE 1.0 V VDD I LOW LINE 2 * I (MODE=1) 0 (MODE = 0) CLK -+ VFF 3 RC 5 S Q RD RD RD Q PWM LATCH 7 OUT 8 VDD 6 GND 1 ILIM -- 30 * I (MODE=1) 80 Ω (MODE = 0) Q + S + RD Q UVLO UCC35705 (8.8 V/8 V) UCC35706 (12 V/8 V) -- 100 mV 0.
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UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 FUNCTIONAL DESCRIPTION V IN RT R DISCH RC 5 DISCH 4 VDD CT I DISCH 30 * I DISCH 2 * IDISCH VFF 3 R FF Figure 2.
PAGE 7
UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 FUNCTIONAL DESCRIPTION component selection for oscillator with duty cycle clamp (MODE = 1) For a power converter with the following specifications: D D D D D VIN(min) = 18 V VIN(max) = 75 V VIN(shutdown) = 15 V FOSC = 1 MHz DMAX = 0.78 at VIN(min) In this mode, the on-time is approximately: D TON(max) = 780 ns D TOFF(min) = 220 ns D VFF(min) = 18 = 1.
PAGE 8
UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 FUNCTIONAL DESCRIPTION oscillator without duty cycle clamp (MODE = 0) In this mode, the timing capacitor is discharged through a low impedance directly to ground. The DISCH pin is externally grounded. A comparator connected to DISCH senses the ground connection and disables both the discharge current source and VFF current source.
PAGE 9
UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 FUNCTIONAL DESCRIPTION component selection for oscillator without duty cycle clamp (MODE = 0) For a power converter with the following specifications: D D D D VIN(min) = 18 V VIN(max) = 75 V VIN(shutdown) = 15 V FOSC = 1 MHz With these specifications, V FF(min) = 18 = 1.2 V 15 (1) Pick CT = 220 pF (2) Calculate RT.
PAGE 10
UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 TYPICAL CHARACTERISTICS OPERATING CURRENT (AT 1mHz) vs TEMPERATURE LOW-LINE THRESHOLD vs. TEMPERATURE 1.05 4.7 1.04 4.6 1.03 Low-Line Threshold -- V 4.8 IDD -- mA 4.5 4.4 4.3 4.2 1.02 1.01 1.00 0.99 4.1 0.98 4.0 0.97 3.9 0.96 3.8 0.
PAGE 11
UCC25705, UCC25706, UCC35705, UCC35706 HIGH-SPEED VOLTAGE MODE PULSE WIDTH MODULATOR SLUS473B -- NOVEMBER 1999 -- REVISED OCTOBER 2010 TYPICAL CHARACTERISTICS CURRENT-LIMIT THRESHOLD vs TEMPERATURE CURRENT-LIMIT PROP DELAY vs TEMPERATURE 35 220 33 215 Current-Limit Prop Delay --ns Current-Limit Threshold --mV 31 210 205 200 195 190 29 27 25 23 21 19 185 17 180 15 --50 --25 0 25 50 75 100 125 --50 --25 0 25 50 75 100 125 Temperature °C Temperature °C Figure 10 Figure 11 Revis
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 10-Jun-2014 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.
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PACKAGE MATERIALS INFORMATION www.ti.com 16-Aug-2012 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant UCC25705DGKTR VSSOP DGK 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 UCC25705DTR SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1 UCC35705DTR SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 16-Aug-2012 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) UCC25705DGKTR VSSOP DGK 8 2500 367.0 367.0 35.0 UCC25705DTR SOIC D 8 2500 367.0 367.0 35.0 UCC35705DTR SOIC D 8 2500 367.0 367.0 35.
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