Fairchild Semiconductor ML4801CP Datasheet
March 2001
15
VEAO
IEAO
V
FB
I
AC
V
RMS
I
SENSE
RAMP 1
OSCILLATOR
OVP
PFC I
LIMIT
UVLO
V
REF
PULSE WIDTH MODULATOR
POWER FACTOR CORRECTOR
2.5V
+
-
-
+
16
2
4
3
7.5V
REFERENCE
14
V
CC
13
V
CC
VEA
8
+
–
IEA
1
+
+
-
PFC OUT
12
SRQ
Q
SRQ
Q
2.75V
-1V
RAMP 2
9
PWM OUT
11
GND
10
SRQ
Q
V
DC
6
SS
5
RTC
T
7
V
CC
DUTY CYCLE
LIMIT
+
-
1.5V
-
+
2.5V
V
FB
-
+
8V
8V
VIN OK
GAIN
MODULATOR
V
CC
÷2
1.6kΩ
1.6kΩ
1.25V
25µA
-
+
DC I
LIMIT
PRELIMINARY
ML4801
Variable Feedforward PFC/PWM Controller Combo
GENERAL DESCRIPTION
The ML4801 is a controller for power factor corrected,
switched mode power supplies. Key features of this
combined PFC and PWM controller are low start-up and
operating currents. 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 specifications. The ML4801 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 PFC frequency of the ML4801 is automatically set at
half that of the PWM frequency generated by the internal
oscillator. This technique allows the user to design with
smaller output 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 and input voltage brownout protection.
BLOCK DIAGRAM
FEATURES
■ Internally synchronized PFC and PWM in one IC
■ Low start-up current (200µA typ.)
■ Low operating current (5.5mA typ.)
■ Low total harmonic distortion
■ Reduces ripple current in the storage capacitor
between the PFC and PWM sections
■ Average current continuous boost leading edge PFC
■ High efficiency trailing edge PWM optimized for
current mode operation
■ Current fed gain modulator for improved noise
immunity
■ Brown-out control, overvoltage protection, UVLO, and
soft start
REV. 1.1 3/9/2001
ML4801
PIN CONFIGURATION
ML4801
16-Pin PDIP (P16)
16-Pin Narrow SOIC (S16N)
IEAO
I
SENSE
V
RMS
V
RTC
RAMP 1
PIN DESCRIPTION
PIN NAME FUNCTION
1 IEAO PFC transconductance current error
amplifier output
2I
AC
3I
SENSE
PFC gain control reference input
Current sense input to the PFC current
limit comparator
I
AC
SS
DC
1
2
3
4
5
6
7
T
8
TOP VIEW
16
VEAO
15
V
FB
14
V
REF
13
V
CC
12
PFC OUT
11
PWM OUT
10
GND
9
RAMP 2
PIN NAME FUNCTION
9 RAMP 2 PWM ramp current sense input
10 GND Ground
11 PWM OUT PWM driver output
12 PFC OUT PFC driver output
4V
RMS
Input for PFC RMS line voltage
compensation
5 SS Connection point for the PWM soft start
capacitor
6V
DC
PWM voltage feedback input
13 V
14 V
15 V
CC
REF
FB
Positive supply (connected to an
internal shunt regulator).
Buffered output for the internal 7.5V
reference
PFC transconductance voltage error
amplifier input
7R
TCT
Connection for oscillator frequency
setting components
16 VEAO PFC transconductance voltage error
amplifier output
8 RAMP 1 PFC ramp input
2 REV. 1.1 3/9/2001
ABSOLUTE MAXIMUM RATINGS
ML4801
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 ........................................................ 80°C/W
V
..............................................................................................
CC
Voltage .................................................. -3V to 5V
I
SENSE
Voltage on Any Other Pin ...... GND - 0.3V to V
I
...........................................................................................
REF
I
Input Current .....................................................10mA
AC
+ 0.3V
CC
18V
20mA
Peak PFC OUT Current, Source or Sink ................. 500mA
Peak PWM OUT Current, Source or Sink............... 500mA
PFC OUT, PWM OUT Energy Per Cycle ................... 1.5µJ
Plastic SOIC ...................................................105°C/W
OPERATING CONDITIONS
Temperature Range
ML4801CX ................................................. 0°C to 70°C
ML4801IX ............................................... -40°C to 85°C
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, VCC = 15V, RT = 29.4kΩ, R
T
= Operating Temperature Range (Note 1)
A
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOLTAGE ERROR AMPLIFIER
Input Voltage Range 0 5 V
Transconductance V
Feedback Reference Voltage 2.43 2.50 2.57 V
Input Bias Current Note 2 -0.5 -1.0 µA
Output High Voltage 6.0 6.7 V
Output Low Voltage 0.1 0.4 V
Source Current ∆VIN = ±0.5V, V
Sink Current ∆VIN = ±0.5V, V
Open Loop Gain 60 70 dB
PSRR 11V < VCC < 16.5V 60 70 dB
CURRENT ERROR AMPLIFIER
Input Voltage Range -1.5 2 V
Transconductance V
Input Offset Voltage 0 8 15 mV
Input Bias Current -0.5 -1.0 µA
Output High Voltage 6.0 6.7 V
Output Low Voltage 0.65 1.0 V
Source Current ∆VIN = ±0.5V, V
Sink Current ∆VIN = ±0.5V, V
Open Loop Gain 55 65 dB
PSRR 11V < VCC < 16.5V 60 75 dB
NON INV
NON INV
= 15.4kΩ, CT = 270pF, C
RAMP1
= V
, VEAO = 3.75V 40 65 80 µ
INV
= 6V -40 -70 -150 µA
OUT
= 1.5V 40 70 150 µA
OUT
= V
, VEAO = 3.75V 60 100 120 µ
INV
= 6V -40 -70 -150 µA
OUT
= 1.5V 40 70 150 µA
OUT
RAMP1
= 620pF,
Ω
Ω
REV. 1.1 3/9/2001 3
ML4801
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 I
DC I
VIN OK COMPARATOR
GAIN MODULATOR
OSCILLATOR
COMPARATOR
LIMIT
Threshold Voltage -0.9 -1.0 -1.1 V
∆PFC I
Threshold - Gain Modulator Output 120 220 mV
LIMIT
Delay to Output 150 300 ns
COMPARATOR
LIMIT
Threshold Voltage 1.4 1.5 1.6 V
Input Bias Current ±0.3 ±1 µA
Delay to Output 150 300 ns
Threshold Voltage 2.4 2.5 2.6 V
Hysteresis 0.8 1.0 1.2 V
Gain (Note 3) IAC = 100µA, V
IAC = 50µA, V
IAC = 50µA, V
IAC = 100µA, V
= VFB = 0V 0.65 0.85 1.05
RMS
= 1V, VFB = 0V 1.90 2.20 2.40
RMS
= 1.8V, VFB = 0V 0.90 1.05 1.25
RMS
= 3.3V, VFB = 0V 0.20 0.30 0.40
RMS
Bandwidth IAC = 100µA 10 MHz
Output Voltage I
= 350µA, V
AC
= 1V, 0.65 0.75 0.85 V
RMS
VFB = 0V
Initial Accuracy TA = 25ºC 188 200 212 kHz
Voltage Stability 11V < VCC < 16.5V 1 %
Temperature Stability 2%
Total Variation Over Line and Temp 182 218 kHz
Ramp Valley to Peak Voltage 2.5 V
PFC Dead Time 350 470 600 ns
CT Discharge Current V
RAMP 2
= 0V, V
= 2.5V 3.5 5.5 7.5 mA
RAMP 1
4 REV. 1.1 3/9/2001
ML4801
ELECTRICAL CHARACTERISTICS (Continued)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
REFERENCE
Output Voltage TA = 25ºC, I(V
Line Regulation 11V < VCC < 16.5V 10 25 mV
Load Regulation 1mA < I(V
Temperature Stability 0.4 %
Total Variation Line, Load, Temp 7.35 7.65 V
Long Term Stability TJ = 125ºC, 1000 Hours 5 25 mV
PFC
Minimum Duty Cycle V
Maximum Duty Cycle V
Output Low Voltage I
Output High Voltage I
> 6.7V 0 %
IEAO
< 1.2V 90 95 %
IEAO
= -20mA 0.4 0.8 V
OUT
I
= -100mA 0.7 2.0 V
OUT
I
= -10mA, VCC = 9V 0.4 0.8 V
OUT
= 20mA VCC - 0.8 V
OUT
I
= 100mA VCC - 2.0 V
OUT
Rise/Fall Time CL = 1000pF 50 ns
PWM
DC Duty Cycle Range 0-44 0-47 0-50 %
V
V
Output Low Voltage I
OL
Output High Voltage I
OH
= -20mA 0.4 0.8 V
OUT
I
= -100mA 0.7 2.0 V
OUT
I
= -10mA, VCC = 9V 0.4 0.8 V
OUT
= 20mA VCC - 0. 8 V
OUT
I
= 100mA VCC - 2.0 V
OUT
Rise/Fall Time CL = 1000pF 50 ns
SUPPLY
) = 1mA 7.4 7.5 7.6 V
REF
) < 10mA 10 20 mV
REF
Start-up Current VCC = 12V, CL = 0 200 350 µA
Operating Current VCC = 14V, CL = 0 5.5 7.0 mA
Undervoltage Lockout Threshold 12.4 13.0 13.6 V
Undervoltage Lockout Hysteresis 2.7 3.0 3.3 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 V
- I
Note 3: Gain = K x 5.3V; K = (I
MULO
) x IAC x (VEAO - 0.625V)-1.
OFFSET
pin.
FB
REV. 1.1 3/9/2001 5
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