ML4824IP-1 Fairchild Semiconductor, ML4824IP-1 Datasheet

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ML4824IP-1

Manufacturer Part Number
ML4824IP-1
Description
Manufacturer
Fairchild Semiconductor
Datasheet

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ML4824IP-1
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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
(f
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 includes a
duty cycle limit to prevent transformer saturation.
BLOCK DIAGRAM
PWM
15
2
4
3
7
8
6
5
9
Power Factor Correction and PWM Controller Combo
V FB
I AC
V RMS
I SENSE
RAMP 1
RAMP 2
V DC
SS
DC I LIMIT
2.5V
= f
V CC
PFC
50µA
) and the ML4824-2 (f
8V
+
8V
VEA
VEAO
MODULATOR
1.25V
GAIN
16
3.5k
3.5k
+
PWM
+
IEA
IEAO
+
= 2 x f
(-2 VERSION ONLY)
1
OSCILLATOR
PFC
+
2.5V
V FB
).
POWER FACTOR CORRECTOR
PULSE WIDTH MODULATOR
+
x 2
V IN OK
DUTY CYCLE
FEATURES
LIMIT
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
2.7V
1V
–1V
PFC I LIMIT
+
OVP
+
+
DC I LIMIT
V CCZ
V CCZ
13.5V
UVLO
S
R
S
R
S
R
Q
Q
Q
Q
Q
Q
REFERENCE
7.5V
REV. 1.01 12/7/2000
13
ML4824
V CC
December 2000
PWM OUT
PFC OUT
V REF
14
12
11

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ML4824IP-1 Summary of contents

Page 1

Power Factor Correction and PWM Controller Combo 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 ...

Page 2

ML4824 PIN CONFIGURATION PIN DESCRIPTION PIN NAME FUNCTION 1 IEAO PFC transconductance current error amplifier output 2 I PFC gain control reference input Current sense input to the PFC current SENSE limit comparator 4 V Input for ...

Page 3

ABSOLUTE MAXIMUM RATINGS 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. V Shunt Regulator Current .................................. 55mA CC I Voltage ...

Page 4

ML4824 ELECTRICAL CHARACTERISTICS SMBOL PARAMETER OVP COMPARATOR Threshold Voltage Hysteresis PFC I COMPARATOR LIMIT Threshold Voltage (PFC Gain Modulator Output) LIMIT TH Delay to Output DC I COMPARATOR LIMIT Threshold Voltage Input Bias Current Delay to Output ...

Page 5

ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER PFC Minimum Duty Cycle Maximum Duty Cycle Output Low Voltage Output High Voltage Rise/Fall Time PWM Duty Cycle Range Output Low Voltage Output High Voltage Rise/Fall Time SUPPLY Shunt Regulator Voltage (V V Load Regulation CCZ ...

Page 6

ML4824 TYPICAL PERFORMANCE CHARACTERISTICS 250 200 150 100 (V) Voltage Error Amplifier (VEA) Transconductance (g 16 VEAO V FB VEA 3.5k 15 – + 2.5V + – GAIN V RMS ...

Page 7

FUNCTIONAL DESCRIPTION The ML4824 consists of an average current controlled, continuous boost Power Factor Corrector (PFC) front end and a synchronized Pulse Width Modulator (PWM) back end. The PWM can be used in either current or voltage mode. In voltage ...

Page 8

ML4824 FUNCTIONAL DESCRIPTION 3) The output of the voltage error amplifier, VEAO. The gain modulator responds linearly to variations in this voltage. The output of the gain modulator is a current signal, in the form of a full wave rectified ...

Page 9

FUNCTIONAL DESCRIPTION open-loop crossover frequency should be 1/2 that of the line frequency, or 23Hz for a 47Hz line (lowest anticipated international power frequency). The gain vs. input voltage of the ML4824’s voltage error amplifier has a specially shaped nonlinearity ...

Page 10

ML4824 FUNCTIONAL DESCRIPTION No voltage error amplifier is included in the PWM stage of the ML4824, as this function is generally performed on the output side of the PWM’s isolation boundary. To facilitate the design of optocoupler feedback circuitry, an ...

Page 11

V BIAS R BIAS V CC ML4824 10nF CERAMIC GND Figure 3. External Component Connections to V LEADING/TRAILING MODULATION Conventional Pulse Width Modulation (PWM) techniques employ trailing edge modulation in which the switch will turn on right after the trailing ...

Page 12

ML4824 VIN DC + – REF OSC U4 12 SW2 SW1 VEAO DFF CMP + RAMP R Q – CLK Q CLK Figure 5. Typical Leading Edge ...

Page 13

AC INPUT 85 TO 265VAC F1 C1 3.15A 470nF R2A 357k BR1 4A, 600V R1A 499k R27 39k R2B 357k C3 470nF R1B C30 499k 330µF D12 1A, 50V R3 75k D13 1A, 50V C2 R4 470nF 13k 1 IEAO ...

Page 14

ML4824 PHYSICAL DIMENSIONS 16 PIN 0.02 MIN (0.50 MIN) (4 PLACES) 0.170 MAX (4.32 MAX) 0.125 MIN (3.18 MIN) 14 inches (millimeters) Package: P16 16-Pin PDIP 0.740 - 0.760 (18.79 - 19.31) 0.240 - 0.260 (6.09 - ...

Page 15

PHYSICAL DIMENSIONS 0.400 - 0.414 (10.16 - 10.52) 16 PIN 0.024 - 0.034 (0.61 - 0.86) (4 PLACES) 0.012 - 0.020 0.090 - 0.094 (0.30 - 0.51) (2.28 - 2.39) REV. 1.01 12/7/2000 inches (millimeters) Package: S16W ...

Page 16

... ML4824 ORDERING INFORMATION PART NUMBER ML4824CP-1 ML4824CP-2 ML4824CS-1 ML4824CS-2 ML4824IP-1 ML4824IP-2 ML4824IS-1 ML4824IS-2 DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; ...

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