Fairchild Semiconductor ML4803CP1 Datasheet

January 2001

PRELIMINARY

ML4803

8-Pin PFC and PWM Controller Combo

GENERAL DESCRIPTION

The ML4803 is a space-saving controller for power factor
corrected, switched mode power supplies that offers very
low start-up and operating currents.

Power Factor Correction (PFC) offers the use of smaller,
lower cost bulk capacitors, reduces power line loading
and stress on the switching FETs, and results in a power
supply fully compliant to IEC1000-3-2 specifications. The
ML4803 includes circuits for the implementation of a
leading edge, average current “boost” type PFC and a
trailing edge, PWM.

The ML4803-1’s PFC and PWM operate at the same
frequency, 67kHz. The PFC frequency of the ML4803-2 is
automatically set at half that of the 134kHz PWM. This
higher frequency allows the user to design with smaller
PWM components while maintaining the optimum
operating frequency for the PFC. An overvoltage
comparator shuts down the PFC section in the event of a
sudden decrease in load. The PFC section also includes
peak current limiting for enhanced system reliability.

BLOCK DIAGRAM

4

3

5

6

VEAO

I

SENSE

–1V

V

DC

I

LIMIT

35µA

M1

M7

ONE PIN ERROR AMPLIFIER

PFC I

LIMIT

V

M6

26k

40k

+

–

V

REF

7V

CC

+

COMP

–

–1

M2

PFC/PWM UVLO

1.2V

PFC OFF

–4

PWM – 134kHz

–

COMP

+

M3

R1 C1

OSCILLATOR

PFC – 67kHz

PWM COMPARATOR

–

COMP

+

1.5V

FEATURES

■ Internally synchronized PFC and PWM in one 8-pin IC

■ Patented one-pin voltage error amplifier with advanced

input current shaping technique

■ Peak or average current, continuous boost, leading

edge PFC (Input Current Shaping Technology)

■ High efficiency trailing-edge current mode PWM

■ Low supply currents; start-up: 150µA typ., operating:

2mA typ.

■ Synchronized leading and trailing edge modulation

■ Reduces ripple current in the storage capacitor

between the PFC and PWM sections

■ Overvoltage, UVLO, and brownout protection

■ PFC V

30pF

DUTY CYCLE

LIMIT

DC I

–

+

V

CC

17.5V

M4

+

COMP

–

LIMIT

OVP with PFC Soft Start

CC

7

VCC OVP

+

COMP

16.2V

–

CONTROL

PFC

LOGIC

SOFT START

PWM

CONTROL

LOGIC

REF

V

REF

GND

PFC OUT

LEADING
EDGE PFC

TRAILING

EDGE PWM

PWM OUT

2

1

8

REV. 1.1 1/24/2001

ML4803

PIN CONFIGURATION

PIN DESCRIPTION

PFC OUT

GND

I

SENSE

VEAO

ML4803
8-Pin PDIP (P08)
8-Pin SOIC (S08)

1

2

3

4

TOP VIEW

8

7

6

5

PWM OUT

V

CC

I

LIMIT

V

DC

PIN NAME FUNCTION

1 PFC OUT PFC driver output

2 GND Ground

3I

SENSE

Current sense input to the PFC current
limit comparator

4 VEAO PFC one-pin error amplifier input

PIN NAME FUNCTION

5V

DC

6I

LIMIT

7V

CC

PWM voltage feedback input

PWM current limit comparator input

Positive supply (may require an
external shunt regulator)

8 PWM OUT PWM driver output

2 REV. 1.1 1/24/2001

ABSOLUTE MAXIMUM RATINGS

ML4803

Absolute maximum ratings are those values beyond which
the device could be permanently damaged. Absolute
maximum ratings are stress ratings only and functional
device operation is not implied.

Junction Temperature ............................................. 150°C

Storage Temperature Range...................... –65°C to 150°C

Lead Temperature (Soldering, 10 sec)..................... 260°C

Thermal Resistance (θ

)

JA

Plastic DIP ..................................................... 110°C/W

I

Current (average) ..............................................40mA

CC

MAX ................................................................18.3V

V

CC

I

Voltage .................................................. -5V to 1V

SENSE

Voltage on Any Other Pin ...... GND - 0.3V to V

CC

+ 0.3V

Plastic SOIC ................................................... 160°C/W

OPERATING CONDITIONS

Peak PFC OUT Current, Source or Sink ....................... 1A

Peak PWM OUT Current, Source or Sink..................... 1A

PFC OUT, PWM OUT Energy Per Cycle................... 1.5µJ

Temperature Range

ML4803CX-X ............................................. 0°C to 70°C

ML4803IX-X ........................................... -40°C to 85°C

ELECTRICAL CHARACTERISTICS

Unless otherwise specified, VCC = 15V, TA = Operating Temperature Range (Note 1)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

ONE-PIN ERROR AMPLIFIER

VEAO Output Current TA = 25ºC, V

Line Regulation 10V < VCC < 15V, V

VCC OVP COMPARATOR

Threshold Voltage TA = 0ºC to 70ºC 15.5 16.0 16.5 V

PFC I

DC I

OSCILLATOR

PFC

COMPARATOR

LIMIT

Threshold Voltage -0.9 -1 -1.15 V

Delay to Output 150 300 ns

COMPARATOR

LIMIT

Threshold Voltage 1.4 1.5 1.6 V

Delay to Output 150 300 ns

Initial Accuracy TA = 25°C 626774kHz

Voltage Stability 10V < VCC < 15V 1 %

Temperature Stability 2%

Total Variation Over Line and Temp 60 67 74.5 kHz
Dead Time PFC Only 0.3 0.45 0.65 µs

Minimum Duty Cycle V

Maximum Duty Cycle V
Output Low Impedance 8 15 Ω

EAO

EAO

> 7.0V,I

< 4.0V,I

= 6V 33.5 35.0 36.5 µA

EAO

= 6V 0.1 0.3 µA

EAO

= -0.2V 0 %

SENSE

= 0V 90 95 %

SENSE

Output Low Voltage I

REV. 1.1 1/24/2001 3

= -100mA 0.8 1.5 V

OUT

I

= –10mA, VCC = 8V 0.7 1.5 V

OUT

ML4803

ELECTRICAL CHARACTERISTICS (Continued)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

PFC (Continued)

Output High Impedance 8 15 Ω

Output High Voltage I

Rise/Fall Time CL = 1000pF 50 ns

PWM

Duty Cycle Range TA = 0ºC to 70ºC, ML4803-2 0-43 0-47 0-50 %

Output Low Impedance 8 15 Ω

Output Low Voltage I

Output High Impedance 8 15 Ω

= 100mA, VCC = 15V 13.5 14.2 V

OUT

TA = 0ºC to 70ºC, ML4803-1 0-49.5 0-50 %

= –100mA 0.8 1.5 V

OUT

I

= –10mA, VCC = 8V 0.7 1.5 V

OUT

Output High Voltage I

Rise/Fall Time CL = 1000pF 50 ns

SUPPLY

VCC Clamp Voltage (V

Start-up Current VCC = 11V, CL = 0 0.2 0.4 mA

Operating Current VCC = 15V, CL = 0 2.5 4 mA

Undervoltage Lockout Threshold 11.5 12 12.5 V

Undervoltage Lockout Hysteresis 2.4 2.9 3.4 V

Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions.

)I

CCZ

= 100mA, VCC = 15V 13.5 14.2 V

OUT

= 10mA 16.7 17.5 18.3 V

CC

4 REV. 1.1 1/24/2001