www.fairchildsemi.com
ML4800
Power Factor Correction and PWM Controller
Combo
Features
• Internally synchronized leading-edge PFC and trailing-
edge PWM in one IC
• TriFault Detect™ for UL1950 compliance and enhanced
safety
• Slew rate enhanced transconductance error amplifier for
ultra-fast PFC response
• Low power: 200µA startup current, 5.5mA operating
current
• Low total harmonic distortion, high PF
• Reduced ripple current in storage capacitor between PFC
and PWM sections
• Average current, continuous boost leading edge PFC
• PWM configurable for current-mode or voltage mode
operation
• Current fed gain modulator for improved noise immunity
• Overvoltage and brown-out protection, UVLO, and soft
start
General Description
The ML4800 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
IEC1000-3-2 specification. Intended as a BiCMOS version
of the industry-standard ML4824, the ML4800 includes
circuits for the implementation of leading edge, average
current, “boost” type power factor correction and a trailing
edge, pulse width modulator (PWM). It also includes a
TriFault Detect™ function to help ensure that no unsafe
conditions will result from single component failure in the
PFC. Gate-drivers with 1A capabilities minimize the need
for external driver circuits. Low power requirements improve
efficiency and reduce component costs.
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 brownout
protection. The PWM section can be operated in current or
voltage mode, at up to 250kHz, and includes an accurate
50% 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
OSCILLATOR
R
Q
GAIN
MODULATOR
1.6kΩ
VEA
-
+
1
IEAO
POWER FACTOR CORRECTOR
0.5V
1.6kΩ
IEA
+
-
13
VCC
OVP
+
2.75V
-
TRI-FAULT
+
-
VCC
17V
7.5V
REFERENCE
S
Q
VREF
14
+
-
-1V
+
-
R
S
Q
PFC OUT
Q
12
PFC ILIMIT
DUTY CYCLE
LIMIT
VDC
6
VCC
SS
5
25µA
1.25V
-
+
-
+
PWM OUT
S
VFB
2.45V
-
+
Q
VIN OK
1.0V
-
+
11
R
DC ILIMIT
Q
DC ILIMIT
9
VREF
PULSE WIDTH MODULATOR
VCC
UVLO
REV. 1.0.5 9/25/01
ML4800
PRODUCT SPECIFICATION
Pin Configuration
ML4800
16-Pin PDIP (P16)
16-Pin Narrow SOIC (S16N)
IEAO 1
IAC 2
ISENSE 3
VRMS 4
SS 5
VDC 6
RAMP 1 7
RAMP 2 8
16 VEAO
15 VFB
14 VREF
13 VCC
12 PFC OUT
11 PWM OUT
10 GND
9
DC ILIMIT
TOP VIEW
Pin Description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Name
IEAO
I
AC
I
SENSE
V
RMS
SS
V
DC
RAMP 1
RAMP 2
DC I
LIMIT
GND
PWM OUT
PFC OUT
V
CC
V
REF
V
FB
VEAO
Function
Slew rate enhanced PFC transconductance error amplifier output
PFC AC line reference input to Gain Modulator
Current sense input to the PFC Gain Modulator
PFC Gain Modulator RMS line voltage compensation input
Connection point for the PWM soft start capacitor
PWM voltage feedback input
Oscillator timing node; timing set by R
T
C
T
When in current mode, this pin functions as the current sense input; when in voltage mode,
it is the PWM modulation ramp input.
PWM cycle-by-cycle current limit comparator input
Ground
PWM driver output
PFC driver output
Positive supply
Buffered output for the internal 7.5V reference
PFC transconductance voltage error amplifier input
PFC transconductance voltage error amplifier output
2
REV. 1.0.5 9/25/01
PRODUCT SPECIFICATION
ML4800
Abolute Maximum Ratings
Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum rat-
ings are stress ratings only and functional device operation is not implied.
Parameter
V
CC
I
SENSE
Voltage
Voltage on Any Other Pin
I
REF
I
AC
Input Current
Peak PFC OUT Current, Source or Sink
Peak PWM OUT Current, Source or Sink
PFC OUT, PWM OUT Energy Per Cycle
Junction Temperature
Storage Temperature Range
Lead Temperature (Soldering, 10 sec)
Thermal Resistance (
θ
JA
)
Plastic DIP
Plastic SOIC
-65
-5
GND - 0.3
Min.
Max.
18
0.7
V
CCZ
+ 0.3
10
10
1
1
1.5
150
150
260
80
105
Units
V
V
V
mA
mA
A
A
µJ
°C
°C
°C
°C/W
°C/W
Operating Conditions
Temperature Range
ML4800CX
ML4800IX
Min
0
-40
.Max.
70
85
Units
°C
°C
Electrical Characteristics
Unless otherwise specified, V
CC
= 15V, R
T
= 52.3k
Ω
, C
T
= 470pF, T
A
= Operating Temperature Range (Note 1)
Symbol
Parameter
Input Voltage Range
Transconductance
Feedback Reference Voltage
Input Bias Current
Output High Voltage
Output Low Voltage
Source Current
Sink Current
Open Loop Gain
Power Supply Rejection Ratio
Current Error Amplifier
Input Voltage Range
Transconductance
Input Offset Voltage
V
NON INV
= V
INV
, VEAO = 3.75V
-1.5
50
0
100
4
2
150
15
V
mV
Ω
µ
Ω
11V < V
CC
< 16.5V
V
IN
= ±0.5V, V
OUT
= 6V
V
IN
= ±0.5V, V
OUT
= 1.5V
-40
40
50
50
Note 2
6.0
V
NON INV
= V
INV
, VEAO = 3.75V
Conditions
Min.
0
30
2.43
65
2.5
-0.5
6.7
0.1
-140
140
60
60
0.4
Typ.
Max. Units
5
90
2.57
-1.0
V
V
µA
V
V
µA
µA
dB
dB
Ω
3
Voltage Error Amplifier
µ
Ω
REV. 1.0.5 9/25/01
ML4800
PRODUCT SPECIFICATION
Electrical Characteristics
(Continued)
Unless otherwise specified, V
CC
= 15V, R
T
= 52.3k
Ω
, C
T
= 470pF, T
A
= Operating Temperature Range (Note 1)
Symbol
Parameter
Input Bias Current
Output High Voltage
Output Low Voltage
Source Current
Sink Current
Open Loop Gain
Power Supply Rejection Ratio
OVP Comparator
Threshold Voltage
Hysteresis
Tri-Fault Detect
Fault Detect HIGH
Time to Fault Detect HIGH
V
FB
= V
FAULT DETECT LOW
to
V
FB
= OPEN. 470pF from V
FB
to
GND
0.4
-0.9
120
2.65
2.75
2
2.85
4
V
ms
2.65
175
2.75
250
2.85
325
V
mV
11V < V
CC
< 16.5V
V
IN
= ±0.5V, V
OUT
= 6V
V
IN
= ±0.5V, V
OUT
= 1.5V
-40
40
60
60
6.0
Conditions
Min.
Typ.
-0.5
6.7
0.65
-104
160
70
75
1.0
Max. Units
-1.0
µA
V
V
µA
µA
dB
dB
Fault Detect LOW
PFC I
LIMIT
Comparator
Threshold Voltage
(PFC I
LIMIT
V
TH
- Gain
Modulator Output)
Delay to Output
DC I
LIMIT
Comparator
Threshold Voltage
Input Bias Current
Delay to Output
V
IN
OK Comparator
Threshold Voltage
Hysteresis
GAIN Modulator
Gain (Note 3)
I
AC
= 100µA, V
RMS
= V
FB
= 0V
I
AC
= 50µA, V
RMS
= 1.2V, V
FB
= 0V
I
AC
= 50µA, V
RMS
= 1.8V, V
FB
= 0V
I
AC
= 100µA, V
RMS
= 3.3V, V
FB
= 0V
Bandwidth
Output Voltage
Oscillator
Initial Accuracy
Voltage Stability
Temperature Stability
Total Variation
Ramp Valley to Peak Voltage
Line, Temp
T
A
= 25°C
11V < V
CC
< 16.5V
I
AC
= 100µA
I
AC
= 350µA, V
RMS
= 1V, V
FB
= 0V
0.5
-1.0
220
150
0.6
-1.1
V
V
mV
300
1.05
±1
300
2.55
1.2
1.05
2.40
1.25
0.40
ns
V
µA
ns
V
V
0.95
1.0
±0.3
150
2.35
0.8
0.60
1.8
0.85
0.20
0.60
71
2.45
1.0
0.80
2.0
1.0
0.30
10
0.75
76
1
2
MHz
0.9
81
V
kHz
%
%
84
kHz
V
68
2.5
4
REV. 1.0.5 9/25/01
PRODUCT SPECIFICATION
ML4800
Electrical Characteristics
(Continued)
Unless otherwise specified, V
CC
= 15V, R
T
= 52.3kΩ, C
T
= 470pF, T
A
= Operating Temperature Range (Note 1)
Symbol
Parameter
PFC Dead Time
C
T
Discharge Current
Reference
Output Voltage
Line Regulation
Load Regulation
T
A
= 25°C, I(V
REF
) = 1mA
11V <V
CC
<16.5V
0mA <I(V
REF
) < 10mA;
T
A
= 0°C to 70°C
0mA < I(V
REF
) < 5mA;
T
A
= –40°C to 85°C
Temperature Stability
Total Variation
Long Term Stability
PFC
Minimum Duty Cycle
Maximum Duty Cycle
Output Low Voltage
V
IEAO
> 4.0V
V
IEAO
< 1.2V
I
OUT
= -20mA
I
OUT
= -100mA
I
OUT
= 10mA, V
CC
= 9V
Output High Voltage
Rise/Fall Time
PWM
Duty Cycle Range
Output Low Voltage
I
OUT
= -20mA
I
OUT
= -100mA
I
OUT
= 10mA, V
CC
= 9V
Output High Voltage
Rise/Fall Time
Supply
Start-up Current
Operating Current
Undervoltage Lockout
Threshold
Undervoltage Lockout
Hysteresis
V
CC
= 12V, C
L
= 0
14V, C
L
= 0
12.4
2.5
200
5.5
13
2.8
350
7
13.6
3.1
µA
mA
V
V
I
OUT
= 20mA
I
OUT
= 100mA
C
L
= 1000pF
V
CC
- 0.8V
V
CC
- 2V
50
0-44
0-47
0.4
0.7
0.4
0-49
0.8
2.0
0.8
%
V
V
V
V
V
ns
I
OUT
= 20mA
I
OUT
= 100mA
C
L
= 1000pF
V
CC
- 0.8V
V
CC
- 2V
50
90
95
0.4
0.7
0.4
0.8
2.0
0.8
0
%
%
V
V
V
V
V
ns
Line, Load, Temp
T
J
= 125°C, 1000 Hours
7.35
5
7.4
7.5
10
10
10
0.4
7.65
25
7.6
25
20
20
V
mV
mV
mV
%
V
mV
V
RAMP 2
= 0V, V
RAMP 1
= 2.5V
Conditions
Min.
350
3.5
5.5
Typ.
Max. Units
650
7.5
ns
mA
Notes
1. Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions.
2. Includes all bias currents to other circuits connected to the V
FB
pin.
3. Gain = K x 5.3V; K = (I
GAINMOD
- I
OFFSET
) x [I
AC
(VEAO - 0.625)]
-1
; VEAO
MAX
=5V.
REV. 1.0.5 9/25/01
5
