NCP1200A
PWM Current−Mode
Controller for Universal
Off−Line Supplies Featuring
Low Standby Power
Housed in SOIC−8 or PDIP−8 package, the NCP1200A enhances
the previous NCP1200 series by offering a reduced optocoupler
current together with an increased drive capability. Due to its novel
concept, the circuit allows the implementation of complete off−line
AC−DC adapters, battery charger or a SMPS where standby power is a
key parameter.
With an internal structure operating at a fixed 40 kHz, 60 kHz or
100 kHz, the controller supplies itself from the high−voltage rail,
avoiding the need of an auxiliary winding. This feature naturally eases
the designer task in battery charger applications. Finally,
current−mode control provides an excellent audio−susceptibility and
inherent pulse−by−pulse control.
When the current setpoint falls below a given value, e.g. the output
power demand diminishes, the IC automatically enters the so−called
skip cycle mode and provides excellent efficiency at light loads.
Because this occurs at a user adjustable low peak current, no acoustic
noise takes place.
The NCP1200A features an efficient protective circuitry which, in
presence of an overcurrent condition, disables the output pulses while
the device enters a safe burst mode, trying to restart. Once the default
has gone, the device auto−recovers.
Features
8
1
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MINIATURE PWM
CONTROLLER FOR HIGH
POWER AC−DC WALL
ADAPTERS AND OFFLINE
BATTERY CHARGERS
MARKING
DIAGRAMS
8
8
1
SOIC−8
D SUFFIX
CASE 751
1
8
PDIP−8
P SUFFIX
CASE 626
1
1200APxxx
AWL
YYWW
200Ay
ALYW
•
•
•
•
•
•
•
•
•
•
•
•
Pb−Free Packages are Available
No Auxiliary Winding Operation
Auto−Recovery Internal Output Short−Circuit Protection
Extremely Low No−Load Standby Power
Current−Mode Control with Skip−Cycle Capability
Internal Temperature Shutdown
Internal Leading Edge Blanking
250 mA Peak Current Capability
Internally Fixed Frequency at 40 kHz, 60 kHz and 100 kHz
Direct Optocoupler Connection
SPICE Models Available for TRANsient and AC Analysis
Pin to Pin Compatible with NCP1200
= Specific Device Code
(40, 60 or 100)
y
= Specific Device Code
(4 for 40, 6 for 60, 1 for 100)
A
= Assembly Location
WL, L = Wafer Lot
Y, YY = Year
W, WW = Work Week
xxx
PIN CONNECTIONS
Adj 1
FB 2
CS 3
GND 4
(Top View)
8 HV
7 NC
6 V
CC
5 Drv
Typical Applications
•
AC−DC Adapters for Portable Devices
•
Offline Battery Chargers
•
Auxiliary Power Supplies (USB, Appliances, TVs, etc.)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 14 of this data sheet.
Semiconductor Components Industries, LLC, 2005
January, 2005− Rev. 7
1
Publication Order Number:
NCP1200A/D
NCP1200A
+
NCP1200A
1
2
EMI
FILTER
UNIVERSAL
INPUT
3
4
Adj
FB
CS V
CC
GND Drv
HV
8
7
6
5
1N4007*
+
V
OUT
+
*Please refer to the application information section.
Figure 1. Typical Application Example
PIN FUNCTION DESCRIPTION
Pin No.
1
Pin Name
Adj
Function
Adjust the skipping peak current
Pin Description
This pin lets you adjust the level at which the cycle skipping process takes
place. Shorting this pin to ground, permanently disables the skip cycle
feature.
By connecting an optocoupler to this pin, the peak current setpoint is
adjusted accordingly to the output power demand.
This pin senses the primary current and routes it to the internal comparator
via an L.E.B.
−
The driver’s output to an external MOSFET.
This pin is connected to an external bulk capacitor of typically 10
mF.
This unconnected pin ensures adequate creepage distance.
Connected to the high−voltage rail, this pin injects a constant current into
the V
CC
bulk capacitor.
2
3
4
5
6
7
8
FB
CS
GND
Drv
V
CC
NC
HV
Sets the peak current setpoint
Current sense input
The IC ground
Driving pulses
Supplies the IC
−
Generates the V
CC
from the line
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2
NCP1200A
Adj
1
HV CURRENT
SOURCE
80 k
1.2 V
SKIP CYCLE
COMPARATOR
INTERNAL V
CC
HV
8
FB
2
+
−
NC
UVLO HIGH AND LOW
INTERNAL REGULATOR
7
24 k
CURRENT
SENSE
3
250 ns
L.E.B.
40−60−100 kHz
CLOCK
SET
Q FLIP−FLOP
DCmax = 80%
RESET
Q
V
CC
6
20 k
GROUND
4
+
−
V
REF
5V
57 k
+
−
1V
OVERLOAD?
FAULT DURATION
±250
mA
Drv
5
25 k
Figure 2. Internal Circuit Architecture
MAXIMUM RATINGS
Rating
Power Supply Voltage
Thermal Resistance Junction−to−Air, PDIP−8 Version
Thermal Resistance Junction−to−Air, SOIC Version
Maximum Junction Temperature
Temperature Shutdown
Storage Temperature Range
ESD Capability, Human Body Model Model (All pins except V
CC
and HV)
ESD Capability, Machine Model
Maximum Voltage on Pin 8 (HV), Pin 6 (V
CC
) Grounded
Maximum Voltage on Pin 8 (HV), Pin 6 (V
CC
) Decoupled to Ground with 10
mF
Minimum Operating Voltage on Pin 8 (HV)
Symbol
V
CC
R
qJA
R
qJA
T
J(max)
−
−
−
−
−
−
−
Value
16
100
178
150
145
−60
to +150
2.0
200
450
500
40
Unit
V
°C/W
°C/W
°C
°C
°C
kV
V
V
V
V
Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit
values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied,
damage may occur and reliability may be affected.
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3
NCP1200A
ELECTRICAL CHARACTERISTICS
(For typical values T
J
= 25°C, for min/max values T
J
= 0°C to +125°C, Max T
J
= 150°C,
Characteristic
Dynamic Self−Supply
(All frequency versions, otherwise noted)
V
CC
Increasing Level at which the Current Source Turns−Off
V
CC
Decreasing Level at which the Current Source Turns−On
V
CC
Decreasing Level at which the Latchoff Phase Ends
Internal IC Consumption, No Output Load on Pin 5
Internal IC Consumption, 1.0 nF Output Load on Pin 5, F
SW
= 40 kHz
Internal IC Consumption, 1.0 nF Output Load on Pin 5, F
SW
= 60 kHz
Internal IC Consumption, 1.0 nF Output Load on Pin 5, F
SW
= 100 kHz
Internal IC Consumption, Latchoff Phase
Internal Startup Current Source
(T
J
> 0°C, pin 8 biased at 50 V)
High−Voltage Current Source, V
CC
= 10 V
High−Voltage Current Source, V
CC
= 0
Drive Output
Output Voltage Rise−Time @ CL = 1.0 nF, 10−90% of Output Signal
Output Voltage Fall−Time @ CL = 1.0 nF, 10−90% of Output Signal
Source Resistance
Sink Resistance
Current Comparator
(Pin 5 unloaded unless otherwise noted)
Input Bias Current @ 1.0 V Input Level on Pin 3
Maximum Internal Current Setpoint (Note 3)
Default Internal Current Setpoint for Skip Cycle Operation
Propagation Delay from Current Detection to Gate OFF State
Leading Edge Blanking Duration (Note 3)
Internal Oscillator
(V
CC
= 11 V, pin 5 loaded by 1.0 kW)
Oscillation Frequency, 40 kHz Version
Built−in Frequency Jittering, f
sw
= 40 kHz
Oscillation Frequency, 60 kHz Version
Built−in Frequency Jittering, f
sw
= 60 kHz
Oscillation Frequency, 100 kHz Version
Built−in Frequency Jittering, f
sw
= 100 kHz
Maximum Duty Cycle
Feedback Section
(V
CC
= 11 V, pin 5 unloaded)
Internal Pullup Resistor
Pin 3 to Current Setpoint Division Ratio
Skip Cycle Generation
Default Skip Mode Level
Pin 1 Internal Output Impedance
1. Max value at T
J
= 0°C.
2. Maximum value @ T
J
= 25°C, please see characterization curves.
3. Pin 5 loaded by 1.0 nF.
V
skip
Z
out
1
1
0.95
−
1.2
22
1.45
−
V
kW
R
up
I
ratio
2
−
−
−
20
3.3
−
−
kW
−
f
OSC
f
jitter
f
OSC
f
jitter
f
OSC
f
jitter
Dmax
−
−
−
−
−
−
−
37
−
53
−
90
−
74
43
350
61
460
103
620
83
48
−
68
−
114
−
87
kHz
kHz
kHz
kHz
kHz
kHz
%
I
IB
I
Limit
I
Lskip
T
DEL
T
LEB
3
3
3
3
3
−
0.8
−
−
−
0.02
0.9
360
90
250
−
1.0
−
160
−
mA
V
mV
ns
ns
T
r
T
f
R
OH
R
OL
5
5
5
5
−
−
27
5.0
67
25
40
10
−
−
61
21
ns
ns
W
W
IC1
IC2
8
8
4.0
−
7.0
13
−
−
mA
mA
V
CC(off)
V
CC(on)
V
CC(latch)
ICC1
ICC2
ICC2
ICC2
ICC3
6
6
6
6
6
6
6
6
11.2
9.0
−
−
−
−
−
−
12.1
10
5.4
750
1.2
1.4
1.9
350
13.1
11
−
1000
(Note 1)
1.4
(Note 2)
1.6
(Note 2)
2.2
(Note 2)
−
V
V
V
mA
mA
mA
mA
mA
Symbol
Pin
Min
Typ
Max
Unit
V
CC
= 11 V unless otherwise noted.)
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4
NCP1200A
TYPICAL CHARACTERISTICS
70
60
50
LEAKAGE (mA)
40
30
20
10
0
−25
0
25
50
75
100
125
V
CC(off)
, THRESHOLD (V)
12.5
12.3
12.1
11.9
11.7
11.5
11.3
11.1
−25
0
25
50
75
100
125
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 3. HV Pin Leakage Current vs. Temperature
10.2
10.1
10.0
ICC1 (mA)
9.9
9.8
9.7
9.6
−25
900
850
800
750
700
Figure 4. V
CC(off)
vs. Temperature
100 kHz
V
CC(on)
, (V)
60 kHz
40 kHz
650
600
−25
0
25
50
75
100
125
0
25
50
75
100
125
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 5. V
CC(on)
vs. Temperature
2.10
1.90
1.70
ICC2 (mA)
1.50
1.30
40 kHz
1.10
0.90
−25
F
SW
(kHz)
100 kHz
Figure 6. ICC1 vs. Temperature
110
104
98
92
86
80
74
68
62
56
50
44
75
100
125
38
−25
0
25
100 kHz
60 kHz
60 kHz
40 kHz
50
75
100
125
0
25
50
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 7. ICC2 vs. Temperature
Figure 8. Switching Frequency vs. Temperature
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