UNITRODE UC1853, UC2853, UC3853 Technical data

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UNITRODE UC1853, UC2853, UC3853 Technical data

UC1853

UC1853

UC2853

UC3853

High Power Factor Preregulator

FEATURES

Complete 8-pin Power Factor Solution

Reduced External Components

RMS Line Voltage Compensation

Precision Multiplier/Squarer/Divider

Internal 75kHz Synchronizable Oscillator

Average Current Mode PWM Control

Overvoltage Protection Comparator

High Current, Clamped Gate Driver

DESCRIPTION

The UC3853 provides simple, yet high performance active power factor correction. Using the same control technique as the UC1854, this 8-pin device exploits a simplified architecture and an internal oscillator to minimize external component count. The UC3853 incorporates a precision multiplier/squarer/divider circuit, voltage and current loop error amplifiers, and a precision voltage reference to implement average current mode control with RMS line voltage compensation. This control technique maintains constant loop gain with changes in input voltage, which minimizes input line current distortion over the worldwide input voltage range.

The internal 75kHz oscillator includes an external clock input, allowing synchronization to downstream converters. Additionally, the device features an overvoltage protection comparator, a clamped MOSFET gate driver which self-biases low during undervoltage lockout, and low startup and supply current.

These devices are available in 8-pin plastic and ceramic dual in-line (DIP) packages, and 8-lead small outline (SOIC) packages. The UC1853 is specified for operation from –55°C to +125°C, the UC2853 is specified for operation from –25°C to +85°C, and the UC3853 is specified for operation from 0°C to +70°C.

BLOCK DIAGRAM

UDG-94120-1

11/97

ABSOLUTE MAXIMUM RATINGS

Supply Voltage (VCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V Output Drive Current,

Continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.125A Peak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5A Output Minimum Voltage . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V IAC Maximum Input Current . . . . . . . . . . . . . . . . . . . . . . . . 1mA IMO Maximum Output Current . . . . . . . . . . . . . . . . . . . . . –2mA IMO Minimum Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V FB Maximum Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 5V VCOMP Maximum Voltage. . . . . . . . . . . . . . . . . . . . . . . . . 6.2V ICOMP Sourcing Current . . . . . . . . . . . . . . . . . . . . Self-Limiting ICOMP Sinking Current . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA ICOMP Maximum Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 7.2V Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C Junction Temperature. . . . . . . . . . . . . . . . . . . –55°C to +150°C Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C

All voltages with respect to GND. Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages.

UC1853

UC2853

UC3853

CONNECTION DIAGRAM

DIL-8, SOIC-8 (Top View)

J or N, D Package

ELECTRICAL CHARACTERISTICS

Unless otherwise stated, these parameters apply for TA = –55°C to +125°C for the

 

UC1853; –25°C to +85°C for the 2853; and 0°C to +70°C for the UC3853; VCC =

 

16V, VFB = 3V, IAC = 100mA, VVCOMP = 3.75V, VICOMP = 3V, TA = TJ.

 

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Undervoltage Lockout Section

 

 

 

 

 

VCC Turn-on Threshold

VVCOMP, VICOMP Open

 

11.5

13

V

Hysteresis

 

1.5

1.8

2.1

V

Supply Current Section

 

 

 

 

 

IVCC Startup

VCC = 8V, IAC = 100μA; VVCOMP, VICOMP Open

 

250

500

mA

IVCC

IAC = 0μA, VICOMP = 0V

 

10

15

mA

Voltage Loop Error Amplifier Section

 

 

 

 

 

Transconductance

IOUT = ± 20μA 0-70C

300

450

575

μmho

 

Temperature

135

 

640

μmho

Input Voltage

0-70C

2.925

3

3.075

V

 

Temperature

2.9

 

3.1

V

AVOL

VVCOMP = 1V – 4V

50

60

 

dB

Output Sink Current

VFB = 3.2V, VVCOMP = 3.75V

20

50

 

μA

Output Source Current

VFB = 2.8V, VVCOMP = 3.75V

 

–50

–20

μA

Output Voltage High

 

5.5

6

 

V

Output Voltage Low

 

 

0.6

0.9

V

Current Loop Error Amplifier Section

 

 

 

 

 

Offset Voltage

 

0

 

6

mV

Voltage Gain

VICOMP = 1V – 4V

 

70

 

dB

Sink Current

VIMO = 100mV, VICOMP = 3V

1

 

 

mA

Source Current

VIMO = –0.1V, VICOMP = 3V

 

–150

–80

mA

Output High

IICOMP = –50mA

6

6.8

 

V

Output Low

IICOMP = 50mA

 

0.3

0.8

V

PWM Modulator Gain

VICOMP = 2V – 3V (Note 1)

 

20

 

%/V

2

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