www.fairchildsemi.com

Datasheet preview, take a look at Datasheets before downloading (Data Sheet is available on manufacturer site)

www.fairchildsemi.com

ML4824
Power Factor Correction and PWM Controller Combo
Features
Internally synchronized PFC and PWM in one IC Low total harmonic distortion Reduces ripple current in the storage capacitor between the PFC and PWM sections Average current, continuous boost leading edge PFC Fast transconductance error amp for voltage loop High efficiency trailing edge PWM can be configured for current mode or voltage mode operation Average line voltage compensation with brownout control PFC overvoltage comparator eliminates output "runaway" due to load removal Current fed gain modulator for improved noise immunity Overvoltage protection, UVLO, and soft start

General Description
The ML4824 is a controller for power factor corrected, switched mode power supplies. Power Factor Correction (PFC) allows the use of smaller, lower cost bulk capacitors, reduces power line loading and stress on the switching FETs, and results in a power supply that fully complies with IEC1000-2-3 specification. The ML4824 includes circuits for the implementation of a leading edge, average current, "boost" type power factor correction and a trailing edge, pulse width modulator (PWM). The device is available in two versions; the ML4824-1 (fPWM fPFC) and the ML4824-2 (fPWM 2 x fPFC). Doubling the switching frequency of the PWM allows the user to design with smaller output components while maintaining the best operating frequency for the PFC. An over-voltage comparator shuts down the PFC section in the event of a sudden decrease in load. The PFC section also includes peak current limiting and input voltage brown-out protection. The PWM section can be operated in current or voltage mode at up to 250kHz and in
cludes a duty cycle limit to prevent transformer saturation.

Block Diagram
16 VEAO VFB 15 2.5V IAC 2 VRMS 4 ISENSE 3 RAMP 1 7 RAMP 2 8 8V VDC 6 VCC SS 5 8V DC ILIMIT 9 PULSE WIDTH MODULATOR VCCZ UVLO 50 A 1.25V

1 IEAO POWER FACTOR CORRECTOR OVP

13 VCC VCCZ 13.5V 7.5V REFERENCE S 1V

VEA

VREF 14

3.5k

IEA

2.7V

Q

GAIN MODULATOR 3.5k

R S

Q PFC OUT Q 12

PFC ILIMIT

R OSCILLATOR (-2 VERSION ONLY) x2 DUTY CYCLE LIMIT

Q

PWM OUT S VFB 2.5V

Q

VIN OK 1V

11

R DC ILIMIT

Q

REV. 1.0.6 11/7/03

ML4824-2 Datasheet Fairchild Download PDF

Add this permalink to your bookmarks for future download of ML4824-2 datasheet

Permalink: http://datasheet.emcelettronica.com/fairchild/ML4824-2

ML4824-2 DATASHEET