August 2000
PRELIMINARY
ML4802
PFC/PWM Controller Combo with Green Mode
BLOCK DIAGRAM
GENERAL DESCRIPTION
The ML 4802 is a controller for power factor corrected,
switched mode power supplies that offers Green Mode
operation and reduced start-up and operating currents.
Green Mode is an efficiency improving circuit feature
which operates automatically in low power situations.
This feature helps meet the demands of Energy StarTM
programs.
Power Factor Correction (PFC) offers the use of lower cost
bulk capacitors, reduces power line loading and stress on
the switching FETs. The ML4802 includes circuits for the
implementation of a leading edge, average current,
"boost" type power factor corrector and a trailing edge
Pulse Width Modulator (PWM).
The PFC frequency of the ML4802 is automatically
synchronized to be one half that of the PWM. This
technique allows the user to design with smaller PWM
components while maintaining the optimum 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 brown-out protection.
FEATURES
s
Internally synchronized PFC and PWM in one IC
s
Green Mode maximizes efficiency during low power
standby operation
s
Low supply current
(Start-up 200A typ., operating 5.5mA typ.)
s
Average current continuous boost leading edge PFC
s
High efficiency trailing edge PWM can be configured
for current mode operation
s
Reduced ripple current in the storage capacitor
between the PFC and PWM sections
s
PFC overvoltage comparator eliminates output
"runaway" due to load removal
s
Current fed gain modulator for improved noise
immunity
s
Overvoltage protection, UVLO, and soft start
1
VEAO
IEAO
OSCILLATOR
OVP
PFC ILIMIT
VREF
PULSE WIDTH MODULATOR
POWER FACTOR CORRECTOR
2.5V
+
-
-
+
7.5V
REFERENCE
VCC
VEA
+
IEA
+
-
PFC OUT
2.75V
-1V
PWM OUT
VCC
+
-
1.5V
-
+
2.43V
VFB
-
+
8V
8V
VIN OK
GAIN
MODULATOR
2
1.8k
1.8k
VLS
1.25V
25A
-
+
DC ILIMIT
8V
PFC
OUTPUT
DRIVER
PFC
CONTROLLER
DC LIMIT
PWM
OUTPUT
DRIVER
VFB
VDC
GREEN
MODE
CONTROLLER
GREEN
MODE
16
1
13
14
12
11
15
VFB
2
IAC
4
VRMS
3
ISENSE
8
RAMP 1
7
RT/CT
9
RAMP 2
6
VDC
5
SS
ML4802
2
Datasheet August 2000
PIN CONFIGURATION
PIN DESCRIPTION
PIN
NAME
FUNCTION
9
RAMP 2
PWM current feedback/overcurrent
limit input
10
GND
Ground
11
PWM OUT PWM driver output
12
PFC OUT
PFC driver output
13
VCC
Positive supply input
14
VREF
Buffered output for the internal 7.5V
reference
15
VFB
PFC voltage error amplifier input
16
VEAO
PFC voltage error amplifier output
PIN
NAME
FUNCTION
1
IEAO
PFC current error amplifier output
2
IAC
PFC gain control reference input
3
ISENSE
Current sense input to the PFC current
limit comparator
4
VRMS
Input for PFC RMS line voltage
compensation
5
SS
Connection point for the PWM soft start
capacitor
6
VDC
PWM feedback voltage input
7
RT/CT
Connection for master (PWM) oscillator
frequency setting components
8
RAMP 1
PFC ramp input
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
IEAO
IAC
ISENSE
VRMS
SS
VDC
RT/CT
RAMP 1
VEAO
VFB
VREF
VCC
PFC OUT
PWM OUT
GND
RAMP 2
TOP VIEW
ML4802
16-Pin PDIP (P16)
16-Pin Narrow SOIC (S16N)
ML4802
3
August 2000 Datasheet
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, VCC = 15V, RT = 29.4k
W, RRAMP1 = 15.4kW, CT = 270pF, CRAMP1 = 620pF,
TA = Operating Temperature Range (Note 1)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VOLTAGE ERROR AMPLIFIER
Input Voltage Range
0
5
V
Transconductance
VNON INV = VINV, VEAO = 3.75V
20
35
50
W
Feedback Reference Voltage
2.4
2.5
2.6
V
Input Bias Current
Note 2
-0.5
-1.0
A
Output High Voltage
6.0
6.7
V
Output Low Voltage
0.2
0.5
V
Source Current
DVIN = 0.5V, VOUT = 6V
1
2.5
4
A
Sink Current
DVIN = 0.5V, VOUT = 1.5V
1
2.5
4
A
Open Loop Gain
50
60
dB
PSRR
11V < VCC < 16.5V
50
60
dB
CURRENT ERROR AMPLIFIER
Input Voltage Range
-1.5
2
V
Transconductance
VNON INV = VINV, VEAO = 3.75V
50
100
150
W
Input Offset Voltage
5
3
10
mV
Input Bias Current
-0.5
-1.0
A
Output High Voltage
6.0
6.7
V
Output Low Voltage
0.65
1.0
V
Source Current
DVIN = 0.5V, VOUT = 6V
-40
-70
-150
A
Sink Current
DVIN = 0.5V, VOUT = 1.5V
40
70
150
A
Open Loop Gain
60
75
dB
PSRR
11V < VCC < 16.5V
60
75
dB
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.
VCC .......................................................................... 18V
ISENSE Voltage ................................................3V to 5V
Voltage on Any Other Pin .... GND 0.3V to VCC + 0.3V
IREF ....................................................................... 20mA
IAC Input Current ................................................... 10mA
PeakCurrent, Source or Sink
PFC OUT, PWM OUT ....................................... 500mA
PFC OUT, PWM OUT Energy Per Cycle .................. 1.5J
Junction Temperature .............................................. 150C
Storage Temperature Range ..................... 65C to 150C
Lead Temperature (Soldering, 10 sec) ..................... 260C
Thermal Resistance (
qja)
Plastic DIP ....................................................... 80C/W
Plastic SOIC ................................................... 105C/W
OPERATING CONDITIONS
Temperature Range
ML4802CX ................................................. 0C to 70C
ML4802IX .............................................. 40C to 85C
ABSOLUTE MAXIMUM RATINGS
ML4802
4
Datasheet August 2000
ELECTRICAL CHARACTERISTICS (Continued)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
OVP COMPARATOR
Threshold Voltage
2.65
2.75
2.85
V
Hysteresis
175
250
325
mV
PFC ILIMIT COMPARATOR
Threshold Voltage
0.9
1
1.1
V
DPFC ILIMIT Threshold - Gain Modulator Output
120
220
mV
Delay to Output
150
300
ns
DC ILIMIT COMPARATOR
Threshold Voltage
1.4
1.5
1.6
V
Input Bias Current
0.3
1
A
Delay to Output
150
300
ns
VIN OK COMPARATOR
Threshold Voltage
2.33
2.43
2.55
V
Hysteresis
0.8
1.0
1.2
V
GAIN MODULATOR
Gain (Note 3)
IAC = 100A, VRMS = VFB = 0V
0.6
0.8
1.05
IAC = 50A, VRMS = 1.2V, VFB = 0V
1.8
2
2.80
IAC = 50A, VRMS = 1.8V, VFB = 0V
0.8
1
1.25
IAC = 100A, VRMS = 3.3V, VFB = 0V
0.2
0.3
0.4
Bandwidth
IAC = 100A
10
MHz
Output Voltage
IAC = 250A, VRMS = 1.15V,
0.6
0.75
0.9
V
VFB = 0V
OSCILLATOR
Initial Accuracy
TA = 25C
188
200
212
kHz
Voltage Stability
11V < VCC < 16.5V
1
%
Temperature Stability
2
%
Total Variation
Line, Temp
182
218
kHz
Ramp Valley to Peak Voltage
2.5
V
Dead Time
PFC Only
260
400
ns
CT Discharge Current
VRAMP 2 = 0V, VRAMP 1 = 2.5V
3.5
5.5
7.5
mA
GREEN MODE
VGMT-L
Green Mode Threshold Low
VGMT = VDC VLS
70
275
mV
VGMT-H Green Mode Threshold High
VGMT = VDC VLS
360
580
mV
VLS
Level Shift
1.25
V
ML4802
5
August 2000 Datasheet
ELECTRICAL CHARACTERISTICS (Continued)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
REFERENCE
Output Voltage
TA = 25C, I(VREF) = 1mA
7.4
7.5
7.6
V
Line Regulation
11V < VCC < 16.5V
2
30
mV
Load Regulation
1mA < I(VREF) < 10mA
2
20
mV
Temperature Stability
0.4
%
Total Variation
Line, Load, Temp
7.35
7.65
V
Long Term Stability
TJ = 125C, 1000 Hours
5
25
mV
PFC
Minimum Duty Cycle
VIEAO > 4.0V
0
%
Maximum Duty Cycle
VIEAO < 1.2V
85
90
%
Output Low Voltage
IOUT = 20mA
0.4
0.8
V
IOUT = 100mA
0.7
2.0
V
IOUT = 10mA, VCC = 11V
0.8
1.5
V
Output High Voltage
IOUT = 20mA
VCC - 0.8
V
IOUT = 100mA
VCC - 2.0
V
Rise/Fall Time
CL = 1000pF
50
ns
PWM
DC
Duty Cycle Range
0-44
0-47
0-50
%
VOL
Output Low Voltage
IOUT = 20mA
0.4
0.8
V
IOUT = 100mA
0.7
2.0
V
IOUT = 10mA, VCC = 11V
0.8
1.5
V
VOH
Output High Voltage
IOUT = 20mA
VCC - 0. 8
V
IOUT = 100mA
VCC - 2.0
V
Rise/Fall Time
CL = 1000pF
50
ns
SUPPLY
Start-up Current
VCC = 12V, CL = 0
200
350
A
Operating Current
VCC = 14V, CL = 0
5
7
mA
Undervoltage Lockout Threshold
12
13
14
V
Undervoltage Lockout Hysteresis
2.5
2.8
3.1
V
Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions.
Note 2: Includes all bias currents to other circuits connected to the VFB pin.
Note 3: Gain = K x 5.3V; K = (IMULO - IOFFSET) x IAC x (VEAO - 1.5V)
-1
.
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