March 2001
PRELIMINARY
ML4804
Power Factor Correction and PWM Controller Combo
GENERAL DESCRIPTION
The ML4804 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 enhancement of the industry-standard ML4824,
the ML4804 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 DetectTM function to
help ensure that no unsafe conditions will result from
single component failure in the PFC. 1A gate-drive
outputs 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.
FEATURES
I
Internally synchronized leading-edge modulated PFC
and trailing-edge modulated PWM in one IC
I
TriFault Detect
TM
for UL1950 compliance and
enhanced safety
I
V
CC
OVP provides additonal PFC fault protection
I
Slew rate enhanced transconductance error amplifier
for ultra-fast PFC response
I
Low power: 200
µA startup current, 5.5mA operating
current
I
Low total harmonic distortion, high PF
I
Reduces ripple current in the storage capacitor
between the PFC and PWM sections
I
Average current, continuous boost leading edge PFC
I
PWM configurable for current-mode or voltage mode
operation
I
Overvoltage and brown-out protection, UVLO, and soft
start
BLOCK DIAGRAM
15
VEAO
IEAO
VFB
IAC
VRMS
ISENSE
RAMP 1
OSCILLATOR
OVP
VCCOVP
TRI-FAULT
PFC ILIMIT
UVLO
VREF
PULSE WIDTH MODULATOR
POWER FACTOR CORRECTOR
2.5V
+
-
-
+
16
2
4
3
7.5V
REFERENCE
14
VCC
13
VCC
VEA
7
IEA
1
+
-
PFC OUT
12
S
R
Q
Q
S
R
Q
Q
2.75V
VCC
-1V
RAMP 2
8
PWM OUT
11
S
R
Q
Q
VDC
6
SS
5
DC ILIMIT
9
VCC
DUTY CYCLE
LIMIT
-
+
1.0V
-
+
2.45V
VFB
-
+
VREF
VIN OK
GAIN
MODULATOR
VCC
1.6k
1.6k
1.25V
25µA
-
+
DC ILIMIT
+
16.4V
0.5V
+
+
-
-
+
17V
REV. 1.0.2 3/9/2001
ML4804
2
REV. 1.0.2 3/9/2001
PIN CONFIGURATION
PIN DESCRIPTION
PIN
NAME
FUNCTION
9
DC I
LIMIT
PWM cycle-by-cycle current
limit comparator input
10
GND
Ground
11
PWM OUT
PWM driver output
12
PFC OUT
PFC driver output
13
V
CC
Positive supply
14
V
REF
Buffered output for the internal
7.5V reference
15
V
FB
PFC transconductance voltage
error amplifier input
16
VEAO
PFC transconductance voltage
error amplifier output
PIN
NAME
FUNCTION
1
IEAO
Slew rate enhanced PFC
transconductance error amplifier output
2
I
AC
PFC AC line reference input to Gain
Modulator
3
I
SENSE
Current sense input to the PFC Gain
Modulator
4
V
RMS
PFC Gain Modulator RMS line voltage
compensation input
5
SS
Connection point for the PWM soft start
capacitor
6
V
DC
PWM voltage feedback input
7
RAMP 1
Oscillator timing node; timing set
by R
T
C
T
8
RAMP 2
When in current mode, this pin
functions as the current sense input;
when in voltage mode, it is the PWM
modulation ramp input.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
IEAO
IAC
ISENSE
VRMS
SS
VDC
RAMP 1
RAMP 2
VEAO
VFB
VREF
VCC
PFC OUT
PWM OUT
GND
DC ILIMIT
TOP VIEW
ML4804
16-Pin PDIP (P16)
16-Pin Narrow SOIC (S16N)
ML4804
REV. 1.0.2 3/9/2001
3
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, V
CC
= 15V, R
T
= 52.3k
, C
T
= 470pF, T
A
= Operating Temperature Range (Note 1)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VOLTAGE ERROR AMPLIFIER
Input Voltage Range
0
5
V
Transconductance
V
NON INV
= V
INV
, VEAO = 3.75V
30
65
90
µ
Feedback Reference Voltage
2.43
2.5
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
V
IN
= 2.5V
± 0.5V, V
OUT
= 6V
-40
-140
µA
Sink Current
V
IN
= 2.5V
± 0.5V , V
OUT
= 1.5V
40
140
µA
Open Loop Gain
50
60
dB
Power Supply Rejection Ratio
11V < V
CC
< 16.5V
50
60
dB
CURRENT ERROR AMPLIFIER
Input Voltage Range
-1.5
2
V
Transconductance
V
NON INV
= V
INV
, VEAO = 3.75V
50
100
150
µ
Input Offset Voltage
0
4
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
V
IN
=
±0.5V, V
OUT
= 6V
-40
-104
µA
Sink Current
V
IN
=
±0.5V, V
OUT
= 1.5V
40
160
µA
Open Loop Gain
60
70
dB
Power Supply Rejection Ratio
11V < V
CC
< 16.5V
60
75
dB
OVP COMPARATOR
Threshold Voltage
2.65
2.75
2.85
V
Hysteresis
180
280
350
mV
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
CC ..............................................................................................
18V
I
SENSE
Voltage ............................................... -5V to 0.7V
Voltage on Any Other Pin ..... GND - 0.3V to V
CCZ
+ 0.3V
I
REF ...........................................................................................
10mA
I
AC
Input Current ..................................................... 10mA
Peak PFC OUT Current, Source or Sink ....................... 1A
Peak PWM OUT Current, Source or Sink ..................... 1A
PFC OUT, PWM OUT Energy Per Cycle ................... 1.5
µJ
Junction Temperature ............................................. 150
°C
Storage Temperature Range ....................... -65
°C to 150°C
Lead Temperature (Soldering, 10 sec) ..................... 260
°C
Thermal Resistance (
JA
)
Plastic DIP ........................................................... 80
°C/W
Plastic SOIC ...................................................... 105
°C/W
OPERATING CONDITIONS
Temperature Range
ML4804CX .................................................... 0
°C to 70°C
ML4804IX .................................................. -40
°C to 85°C
ML4804
4
REV. 1.0.2 3/9/2001
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
TRI-FAULT DETECT
Fault Detect HIGH
2.65
2.75
2.85
V
Time to Fault Detect HIGH
V
FB
= V
FAULT DETECT LOW
2
4
ms
to V
FB
=OPEN; 470pF from V
FB
to GND
Fault Detect LOW
0.4
0.5
0.6
V
V
CC
OVP COMPARATOR
Threshold Voltage
T
A
= Operation Temp Range
16.4
V
Hysteresis
T
A
= Operation Temp Range
1.7
2.0
2.3
V
PFC I
LIMIT
COMPARATOR
Threshold Voltage
-0.9
-1.0
-1.1
V
(PFC I
LIMIT
V
TH
- Gain Modulator Output)
120
220
mV
Delay to Output
150
300
ns
DC I
LIMIT
COMPARATOR
Threshold Voltage
0.95
1.0
1.05
V
Input Bias Current
±0.3
±1
µA
Delay to Output
150
300
ns
V
IN
OK COMPARATOR
Threshold Voltage
2.35
2.45
2.55
V
Hysteresis
0.8
1.0
1.2
V
GAIN MODULATOR
Gain (Note 3)
I
AC
= 100
µA, V
RMS
= V
FB
= 0V
0.60
0.80
1.05
I
AC
= 50
µA, V
RMS
= 1.2V, V
FB
= 0V
1.8
2.0
2.40
I
AC
= 50
µA, V
RMS
= 1.8V, V
FB
= 0V
0.85
1.0
1.25
I
AC
= 100
µA, V
RMS
= 3.3V, V
FB
= 0V
0.20
0.30
0.40
Bandwidth
I
AC
= 100
µA
10
MHz
Output Voltage
I
AC
= 350
µA, V
RMS
= 1V,
0.60
0.75
0.9
V
V
FB
= 0V
OSCILLATOR
Initial Accuracy
T
A
= 25
°C
71
76
81
kHz
Voltage Stability
11V < V
CC
< 16.5V
1
%
Temperature Stability
2
%
Total Variation
Line, Temp
68
84
kHz
Ramp Valley to Peak Voltage
2.5
V
PFC Dead Time
520
600
ns
f
OSC
= 250kHz, R
T
= 75.0k
, C
T
= 100pF
250
330
ns
C
T
Discharge Current
V
RAMP 2
= 0V, V
RAMP 1
= 2.5V
3.5
5.5
7.5
mA
ML4804
REV. 1.0.2 3/9/2001
5
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
REFERENCE
Output Voltage
T
A
= 25
°C, I(V
REF
) = 1mA
7.4
7.5
7.6
V
Line Regulation
11V < V
CC
< 16.5V
10
25
mV
Load Regulation
0mA < I(V
REF
) < 10mA;
10
20
mV
TA = 0ºC to 70ºC
0mA <I(V
REF
) <5mA:
10
20
mV
TA = 40ºC to 85ºC
Temperature Stability
0.4
%
Total Variation
Line, Load, Temp
7.35
7.65
V
Long Term Stability
T
J
= 125
°C, 1000 Hours
5
25
mV
PFC
Minimum Duty Cycle
V
IEAO
> 4.0V
0
%
Maximum Duty Cycle
V
IEAO
< 1.2V
90
95
%
Output Low Voltage
I
OUT
= -20mA
0.4
0.8
V
I
OUT
= -100mA
0.7
2.0
V
I
OUT
= 10mA, V
CC
= 9V
0.4
0.8
V
Output High Voltage
I
OUT
= 20mA
V
CC
0.8V
V
I
OUT
= 100mA
V
CC
- 2V
V
Rise/Fall Time
C
L
= 1000pF
50
ns
PWM
Duty Cycle Range
0-44
0-47
0-49
%
Output Low Voltage
I
OUT
= -20mA
0.4
0.8
V
I
OUT
= -100mA
0.7
2.0
V
I
OUT
= 10mA, V
CC
= 9V
0.4
0.8
V
Output High Voltage
I
OUT
= 20mA
V
CC
0.8V
V
I
OUT
= 100mA
V
CC
- 2V
V
Rise/Fall Time
C
L
= 1000pF
50
ns
SUPPLY
Start-up Current
V
CC
= 12V, C
L
= 0
200
350
µA
Operating Current
14V, C
L
= 0
5.5
7
mA
Undervoltage Lockout Threshold
12.4
13
13.6
V
Undervoltage Lockout Hysteresis
(Note 4)
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 V
FB
pin.
Note 3: Gain = K x 5.3V; K = (I
GAINMOD
- I
OFFSET
) x [I
AC
(VEAO - 0.625)]
-1
; VEAO
MAX
=5V.
Note 4: UVLO Hysteresis
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