Texas Instruments UCC3570QTR, UCC3570Q, UCC3570N, UCC3570DTR, UCC3570D Datasheet

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UCC1570 UCC2570 UCC3570

Low Power Pulse Width Modulator

DESCRIPTION

The UCC1570 family of pulse width modulators is intended for application in isolated switching supplies using primary side control and a voltage mode feedback loop.Made with a BiCMOS process, these devices feature low startup current for efficient off-line starting with a bootstrapped low voltage supply. Operating current is also very low; yet these devices maintain the ability to drive a power MOSFET gate at frequencies above 500kHz.

Voltage feedforward provides fast and accurate response to wide line voltage variation without the noise sensitivity of current mode control. Fast current limiting is included with the ability to latch off after a programmable number of repetitive faults has occurred. This allows the power supply to ride through a temporary overload, while still shutting down in the event of a permanent fault. Additional versatility is provided with a maximum duty cycle clamp programmable within a 20% to 80% range and line voltage sensing with a programmable window of allowable operation.

10 I3

10 I4

VFWD

FREQ

SLOPE

RAMP

ISET

CLOCK

GENERATOR

HIGH

LINE

LOW LINE

FEEDBK

SOFTST

CURLIM

CURRENT

LIMIT

CLK

RAMP VALLEY

RAMP PEAK

RAMP

LATCH

GENERATOR

4.5V

VREF

15V

GND

13/9V

VCC

OUT

PGND

PWM

LATCH

0.2V

CLK

COUNT

SHUTDOWN

LATCH

SHUTDOWN

0.6V

R S

12 13

BLOCK DIAGRAM

04/99

FEATURES

• Low Power BiCMOS Process

• 85µA Start-up Current

• 1mA Run Current

• 1A Peak Gate Drive Output

• Voltage Feed Forward

• Programmable Duty Cycle Clamp

• Optocoupler Interface

• 500kHz Operation

• Soft Start

• Fault Counting Shutdown

• Fault Latch Off or Automatic Restart

UCC1570 UCC2570 UCC3570

Supply Voltage

(Limit Supply Current to 20mA) . . . . . . . Self Limiting at 15V

Supply Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +20mA

Analog Inputs (CURLIM, VFWD, FEEBK) . . . . . . . . . . . . . . 6V

Programming Current I

SLOPE,IISET

. . . . . . . . . . . . . . . . . –1mA

Output Current I

OUT

DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±180mA

Pulse (0.5ms) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1.2A

Note: All voltages are with respect to GND. Currents are positive into the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of package.

ABSOLUTE MAXIMUM RATINGS CONNECTION DIAGRAMS

DIL-14 (TOP VIEW) N or J Package

PLCC-20 (TOP VIEW) Q Package

SOIC-14 (TOP VIEW) D Package

ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for T

= 0 to 70°C for the

UCC3570, TA= –40 to 85°C for the UCC2570, TA=–55 to 125°C for the UCC1570, R

ISET

=100k, R

SLOPE

=121k, C

FREQ

=180pF,

RAMP

=150pF, VCC=11V and TA=TJ.

PARAMETER TEST CONDITIONS Min Typ Max Units

Reference

VREF VCC =10 to 13V, I

VREF

= 0 to 2mA 4.9 5 5.1 V Line Regulation VCC = 10 to 13V 2 10 mV Load Regulation I

VREF

= 0 to 2mA 2 10 mV

Short Circuit Current VREF = 0 10 50 mA

VCC

Vth (On) 12 13 V Vth (Off) 8 9 10 V Hysteresis 345V VCC I

VCC

= 10mA 13.5 15 16 V

VCC

Start VCC = 11V, VCC Comparator Off 85 150 µA

VCC Run

VCC Comparator On 1 1.5 mA

Temperature Range Package

UCC1570J –55°C to +125°C Ceramic Dip UCC2570D –40°C to +85°C SOIC UCC2750N Plastic Dip UCC3570D 0°C to +70°C SOIC UCC3570N Plastic Dip UCC3570Q PLCC

ORDERING INFORMATION

UCC1570 UCC2570 UCC3570

ELECTRICAL CHARACTERISTICS:

Unless otherwise stated, these specifications apply for TA= 0 to 70°C for the

UCC3570, TA= –40 to 85°C for the UCC2570, TA=–55 to 125°C for the UCC1570, R

ISET

=100k, R

SLOPE

=121k, C

FREQ

=180pF,

RAMP

=150pF, VCC=11V and TA=TJ.

PARAMETER TEST CONDITIONS Min Typ Max Units

Line Sense

Vth High Line Comparator 3.9 4 4.1 V Vth Low Line Comparator 0.96 1 1.04 V lib (VFWD) 0 ±100 nA

Oscillator

Frequency 90 100 110 kHz

Ramp Generator

RAMP/ISLOPE

9 10 11 A/A

–I

RAMP/IISET

9 10 11 A/A Peak Ramp Voltage 3.8 4 4.2 V Valley Ramp Voltage 0.95 1 1.05 V ISET Voltage Level 0.95 1 1.05 V

Soft Start

Saturation VCC = 11V, VCC Comparator Off 25 100 mV I

SOFTST/IISET

0.8 1 1.2 A/A

Pulse Width Modulator

lib(FEEDBK) 0 ±100 n A FEEDBK Zero Duty Cycle 0.9 1 1.1 V

Maximum Duty Cycle, (Note 1) 3.8 4 4.2 V

Current Limit

lib(CURLIM) 0 ±100 nA Vth Current Limit 180 200 220 mV Vth Shutdown 500 600 700 mV

Fault Counter

Vth 3.8 4 4.2 V Vsat 0 100 mV I

COUNT/IISET

0.8 1 1.2 A/A

Output Driver

Vsat High I

OUT

= –100mA 0.4 1 V

Vsat Low I

OUT

= 100mA 0.4 1 V

Rise/Fall Time C

OUT

= 1nF, (Note 1) 20 100 ns

Note 1: This parameter guaranteed by design but not 100% tested in production.

VCC: Chip supply voltage pin. Bypass to PGND with a

low ESL/ESR 0.1µF capacitor plus a capacitor for gate charge storage.Lead lengths must be minimum.

PGND: Ground pin for the output driver. Keep connections less than 2cm. Carefully maintain low impedance path for high current return.

OUT: Gate drive output pin. Connect to the gate of a power MOSFET with a resistor greater than 2Ω. Keep connection lengths under 2cm.

VFWD: Voltage Feed Forward and Line Sense pin. Connect to input DC line using a resistive divider.

SLOPE: Program the charging current for RAMP with a resistor from this pin to GND. This pin will follow VFWD.

FEEDBK: Input to the pulse width modulator comparator. Drive this pin with an optocoupler to GND and a resistor to VREF. Modulation input range is from 1V to 4V.

ISET: A resistor from this pin to GND programs RAMP discharge current, FREQ current, SOFTST current, and COUNT current.

PIN DESCRIPTIONS

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