UNITRODE UC1852, UC2852, UC3852 Technical data

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UNITRODE UC1852, UC2852, UC3852 Technical data

UC1852

UC2852

UC3852

High Power-Factor Preregulator

FEATURES

Low-Cost Power Factor Correction

Power Factor Greater Than 0.99

Few External Parts Required

Controlled On-Time Boost PWM

Zero-Current Switching

Limited Peak Current

Min and Max Frequency Limits

Starting Current Less Than 1mA

High-Current FET Drive Output

Under-Voltage Lockout

DESCRIPTION

The UC1852 provides a low-cost solution to active power-factor correction (PFC) for systems that would otherwise draw high peak current pulses from AC power lines. This circuit implements zero-current switched boost conversion, producing sinusoidal input currents with a minimum of external components, while keeping peak current substantially below that of fully-discontinuous converters.

The UC1852 provides controlled switch on-time to regulate the output bulk DC voltage, an off-time defined by the boost inductor, and a zero-current sensing circuit to reactivate the switch cycle. Even though switching frequency varies with both load and instantaneous line voltage, it can be maintained within a reasonable range to minimize noise generation.

While allowing higher peak switch currents than continuous PFCs such as the UC1854, this device offers less external circuitry and smaller inductors, yet better performance and easier line-noise filtering than discontinuous current PFCs with no sacrifice in complexity or cost. The ability to obtain a power factor in excess of 0.99 makes the UC1852 an optimum choice for low-cost applications in the 50 to 500 watt power range. Protection features of these devices include under-voltage lockout, output clamping, peak-current limiting, and maximum-frequency clamping.

The UC1852 family is available in 8-pin plastic and ceramic dual in-line packages, and in the 8-pin small outline IC package (SOIC). The UC1852 is specified for operation from -55°C to +125°C, the UC2852 is specified for operation from -40°C to +85°C, and the UC3852 is specified for operation from 0°C to +70°C.

TYPICAL APPLICATION

UDG-92001

10/94

This Material Copyrighted By Its Respective Manufacturer

ABSOLUTE MAXIMUM RATINGS

Supply Voltage (Low-impedance Source)..........................

30.0V

Supply Current (High-impedance Source) ......................

30.0mA

OUT Current, Peak.............................................................

±1.0A

OUT Energy, Capacitive Load............................................

5.0μJ

Input Voltage, ISNS ............................................................

±5.0V

Input Voltage, VFB.............................................

–0.3V to +10.0V

COMP Current...............................................................

±10.0mA

ISET Current..................................................................

–10.0mA

Power Dissipation at Ta25°C (Note 3) ..............................

1.0W

Storage Temperature .......................................

–65°C to +150°C

Lead Temperature (Soldering, 10 Seconds)...................

+300°C

Note 1: All voltages with respect to GND (Pin 1).

Note 2: All currents are positive into the specified terminal. Note 3: Refers to DIL-8 Package. Consult Packaging Section of Unitrode Integrated Circuits databook for thermal limitations and considerations of package.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UC1852

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UC2852

CONNECTION DIAGRAM

 

 

 

 

 

 

 

UC3852

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DIL–8 (TOP VIEW)

 

 

SOIC–8 (TOP VIEW)

 

 

J or N Package

 

 

 

 

 

 

D Package

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UDG-92002

ELECTRICAL CHARACTERISTICS Unless otherwise stated, VCC=24V, ISET=50kΩ to GND, RAMP=1nF to GND, ISNS= –0.1V, VFB connected to COMP, no load on OUT, –55°C<Ta<+125°C for the UC1852, –40°C<Ta<+85°C for the UC2852, and 0°C<Ta<+70°C for the UC3852, and Ta=Tj.

PARAMETER

TEST CONDITIONS

MIN.

TYP.

MAX.

UNITS

Timer Section

 

 

 

 

 

ISET Voltage

 

4.5

5.0

5.5

V

RAMP Charge Current

RAMP=2.5V

88

98

108

μA

RAMP Discharge Current

ISNS= –1.0V, RAMP=1.0V

12

28

50

mA

RAMP Saturation Voltage

ISNS= –1.0V, IRAMP=100μA

 

0.006

0.200

V

RAMP Threshold - Maximum Frequency

VFB=10V, COMP open

0.92

1.02

1.12

V

RAMP Threshold - PWM Comparator

 

3.9

4.3

4.8

V

Current Sense Comparator

 

 

 

 

 

ISNS Restart Threshold

 

–18

–10

–4

mV

ISNS Fault Threshold

 

–550

–450

–350

mV

ISNS Input Current

 

–100

–30

100

μA

Error Amplifier Section

 

 

 

 

 

VFB Input Voltage

 

4.6

5.0

5.3

V

VFB Input Bias Current

 

–5.00

–0.03

5.00

μA

COMP Sink Current

COMP=7.5V

10

 

 

mA

COMP Source Current

COMP=2.5V

–300

–175

–100

μA

COMP Clamp Voltage

VFB=0.0V, COMP open

9.2

10.0

10.6

V

OUT Output

 

 

 

 

 

OUT Saturation Voltage High

VCC=13V, IOUT= –200mA, RAMP=2V

0.5

1.7

2.5

V

OUT Saturation Voltage Low

IOUT=200mA, ISNS= –1.0V

0.5

1.6

2.2

V

OUT Saturation Voltage Low @ 10mA

IOUT=10mA, ISNS= –1.0V

 

0.05

0.40

V

OUT Clamp Voltage

IOUT= –200mA, RAMP=2V

10.0

12.0

14.5

V

OUT Voltage during UVLO

IOUT=100mA, VCC=0V

0.5

1.0

2.2

V

Overall Section

 

 

 

 

 

Inactive Supply Current

VCC=10V

0.2

0.4

1.0

mA

Active Supply Current

 

3.0

6.0

10.0

mA

VCC Clamp Voltage

ICC=25mA

30

33

36

V

VCC Turn-On Threshold

 

14.5

16.3

17.5

V

VCC Turn-Off Threshold

 

10.5

11.5

13.0

V

VCC Threshold Hysteresis

 

3

5

7

V

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