NCP1244
Fixed Frequency Current
Mode Controller for Flyback
Converters
The NCP1244 is a new fixed−frequency current−mode controller
featuring the Dynamic Self−Supply. This function greatly simplifies
the design of the auxiliary supply and the V
CC
capacitor by activating
the internal startup current source to supply the controller during
start−up, transients, latch, stand−by etc. This device contains a special
HV detector which detect the application unplug from the AC input
line and triggers the X2 discharge current.
It features a timer−based fault detection that ensures the detection of
overload and an adjustable compensation to help keep the maximum
power independent of the input voltage.
Due to frequency foldback, the controller exhibits excellent
efficiency in light load condition while still achieving very low
standby power consumption. Internal frequency jittering, ramp
compensation, and a versatile latch input make this controller an
excellent candidate for the robust power supply designs.
A dedicated Off mode allows to reach the extremely low no load
input power consumption via “sleeping” whole device and thus
minimize the power consumption of the control circuitry.
Features
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MARKING
DIAGRAM
8
SOIC−7
CASE 751U
44Xff
ALYWX
G
1
44Xff = Specific Device Code
X = A or B
ff = 65 or 100
A
= Assembly Location
L
= Wafer Lot
Y
= Year
W
= Work Week
G
= Pb−Free Package
PIN CONNECTIONS
Latch 1
8
HV
•
Fixed−Frequency Current−Mode Operation (65 kHz and 100 kHz
•
•
•
•
•
•
•
•
•
•
•
•
X2 Capacitor in EMI Filter Discharging Feature
•
These Devices are Pb−Free and Halogen Free/BFR Free
frequency options)
FB 2
Frequency Foldback then Skip Mode for Maximized Performance in
6 V
CC
CS 3
Light Load and Standby Conditions
GND 4
5 DRV
Timer−Based Overload Protection with Latched (Option A) or
(Top View)
Auto−Recovery (Option B) Operation
High−voltage Current Source with Dynamic Self−Supply,
Simplifying the Design of the V
CC
Circuitry
ORDERING INFORMATION
See detailed ordering and shipping information in the package
Frequency Modulation for Softened EMI Signature
dimensions section on page 39 of this data sheet.
Adjustable Overpower Protection Dependant on the Bulk Voltage
Latch−off Input Combined with the Overpower Protection Sensing
Input
Typical Applications
V
CC
Operation up to 28 V, With Overvoltage Detection
•
AC−DC Adapters for Notebooks, LCD, and Printers
500/800 mA Source/Sink Drive Peak Current
•
Offline Battery Chargers
Capability
•
Consumer Electronic Power Supplies
10 ms Soft−Start
•
Auxiliary/Housekeeping Power Supplies
Internal Thermal Shutdown
•
Offline Adapters for Notebooks
No−Load Standby Power < 30 mW
©
Semiconductor Components Industries, LLC, 2012
December, 2012
−
Rev. 0
1
Publication Order Number:
NCP1244/D
NCP1244
TYPICAL APPLICATION EXAMPLE
Figure 1. Flyback Converter Application Using the NCP1244
PIN FUNCTION DESCRIPTION
Pin No
1
2
3
4
5
6
Pin Name
LATCH
FB
CS
GND
DRV
VCC
Function
Latch−Off Input
Feedback + Shutdown pin
Current Sense
−
Drive output
VCC input
Pin Description
Pull the pin up or down to latch−off the controller. An internal current source
allows the direct connection of an NTC for over temperature detection.
An optocoupler collector to ground controls the output regulation. The part
goes to the low consumption Off mode if the FB input pin is pulled to GND.
This Input senses the Primary Current for current−mode operation, and
offers an overpower compensation adjustment.
The controller ground
Drives external MOSFET
This supply pin accepts up to 28 Vdc, with overvoltage detection. The pin is
connected to an external auxiliary voltage. It is not allowed to connect
another circuit to this pin to keep low input power consumption.
Connects to the rectified AC line to perform the functions of Start−up
Current Source, Self−Supply and X2 capacitor discharge function and the
HV sensing for the overpower protection purposes. It is not allowed to
connect this pin to DC voltage.
8
HV
High−voltage pin
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2
NCP1244
SIMPLIFIED INTERNAL BLOCK SCHEMATIC
Vdd
Intc
Intc
Vhv sample
HV
OVP_CMP
55 us
Filter
Vovp
2.5V
OVP
VccOVP_CMP
VccOVP
OTP_CMP
VclampRclamp
300 us OTP
Filter
Votp
0.8V
1k
VccOVP 10 us
Filter
26V
AC_Off
LATCH
+Shv
TSD
Vcc_Int
ICstartB
SG & X2 & Vcc
control
Dual HV
start−up
current source
15 mA
VCC
1.2V
UVLO_CMP
UVLO
VccOFF
9.5V
Vdd reg
Vcc regulator
Vcc(reg)
VccRESET
VCC
Clamp
X2 discharge
10.8V regulator
SS_end
Set
RESET
Q
Latch
VccON
ON_CMP
Reset Qb
Vdd
VccON
PowerOnReset_CMP
RESET
5V
3.0V
Off_mode_CMP1
Set
2.2V
Q
ICstart
Von
Reset Qb
Off_mode_CMP2
GoToOffMode timer 150ms
0.4V
Voff
jittering
FM input
Square output
ton_max output
Saw output
OSC 65kHz
freq folback
CSref
PFM input
Ramp_OTA
Vramp_offset
Vfb(reg)
Rfb1
Skip_CMP
SkipB
Vskip
0.7V
1.4V
FB
Internal resitance 20k
FBbuffer
4uMho
Division ratio 5
Rfb3 Rfb2
MAX_ton
PWM_CMP
PWM
IC stopB
Set
Q
VccMIN
VCC
5uA
STOP_CMP
VccMIN
10.5V
12V
10.8V
Vhv sample
Vfb(opc)
DRV
Reset Qb
2.35V
Iopc = 0.5u*(Vhv−125)
Vdd
1uA
Ilimit_CMP
Vfb < 1.5V fix current setpoint 300mV
Vilim
0.7V
Enable
Soft Start timer
SS_end
LatchB
FaultB
V to I
LEB 250ns
SoftStart_CMP
CS
Ilimit
Set
Q
Fault timer
Autorecovery timer
Fault
Latch management
RESET
IC stop
Latch
Reset Qb
LEB 120ns
VCSstop
CSstop_CMP
GND
1.05V
+Shv
TSD
TSD
Figure 2. Simplified Internal Block Schematic
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3
NCP1244
MAXIMUM RATINGS
Rating
DRV
(pin 5)
V
CC
(pin 6)
HV
(pin 8)
V
max
R
qJ−A
Symbol
Maximum voltage on DRV pin
(Dc−Current self−limited if operated within the allowed range) (Note 1)
V
CC
Power Supply voltage, V
CC
pin, continuous voltage
Power Supply voltage, V
CC
pin, continuous voltage (Note 1)
Maximum voltage on HV pin
(Dc−Current self−limited if operated within the allowed range)
Maximum voltage on low power pins (except pin 5, pin 6 and pin 8)
(Dc−Current self−limited if operated within the allowed range) (Note 1)
Thermal Resistance SOIC−7
Junction-to-Air, low conductivity PCB (Note 2)
Junction-to-Air, medium conductivity PCB (Note 3)
Junction-to-Air, high conductivity PCB (Note 4)
Thermal Resistance Junction−to−Case
Operating Junction Temperature
Storage Temperature Range
ESD Capability, HBM model (All pins except HV) per JEDEC Standard JESD22,
Method A114E
ESD Capability, Machine Model per JEDEC Standard JESD22, Method A115A
ESD Capability, Charged Device Model per JEDEC Standard JESD22, Method C101E
Value
–0.3 to 20
±1000
(peak)
–0.3 to 28
±30
(peak)
–0.3 to 500
±20
–0.3 to 10
±10
(peak)
162
147
115
73
−40
to +150
−60
to +150
> 2000
> 200
> 1000
Unit
V
mA
V
mA
V
mA
V
mA
°C/W
R
qJ−C
T
JMAX
T
STRGMAX
°C/W
°C
°C
V
V
V
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. This device contains latch-up protection and exceeds 100 mA per JEDEC Standard JESD78.
2. As mounted on a 80 x 100 x 1.5 mm FR4 substrate with a single layer of 50 mm
2
of 2 oz copper traces and heat spreading area. As specified
for a JEDEC 51-1 conductivity test PCB. Test conditions were under natural convection or zero air flow.
3. As mounted on a 80 x 100 x 1.5 mm FR4 substrate with a single layer of 100 mm
2
of 2 oz copper traces and heat spreading area. As specified
for a JEDEC 51-2 conductivity test PCB. Test conditions were under natural convection or zero air flow.
4. As mounted on a 80 x 100 x 1.5 mm FR4 substrate with a single layer of 650 mm
2
of 2 oz copper traces and heat spreading area. As specified
for a JEDEC 51-3 conductivity test PCB. Test conditions were under natural convection or zero air flow.
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4
NCP1244
ELECTRICAL CHARACTERISTICS
(For typical values T
J
= 25°C, for min/max values T
J
=
−40°C
to +125°C, V
HV
= 125 V,
V
CC
= 11 V unless otherwise noted)
Characteristics
HIGH VOLTAGE CURRENT SOURCE
Minimum voltage for current source
operation
Current flowing out of V
CC
pin
Off−state leakage current
Off−mode HV supply current
V
CC
= 0 V
V
CC
= V
CC(on)
−
0.5 V
V
HV
= 500 V, V
CC
= 15 V
V
HV
= 141 V,
V
HV
= 325 V,
V
CC
loaded by 4.7
mF
cap
V
HV(min)
I
start1
I
start2
I
start(off)
I
HV(off)
−
0.2
5
10
−
−
30
0.5
8
25
45
50
40
0.8
11
50
60
70
V
mA
mA
mA
Test Condition
Symbol
Min
Typ
Max
Unit
SUPPLY
HV current source regulation threshold
Turn−on threshold level, V
CC
going up
HV current source stop threshold
HV current source restart threshold
Turn−off threshold
Overvoltage threshold
Blanking duration on V
CC(off)
and V
CC(ovp)
detection
V
CC
decreasing level at which the internal
logic resets
V
CC
level for I
START1
to I
START2
transition
Internal current consumption (Note 5)
DRV open, V
FB
= 3 V, 65 kHz
DRV open, V
FB
= 3 V, 100 kHz
Cdrv = 1 nF, V
FB
= 3 V, 65 kHz
Cdrv = 1 nF, V
FB
= 3 V, 100 kHz
Off mode (skip or before start−up)
Fault mode (fault or latch)
X2 DISCHARGE
Comparator hysteresis observed at HV pin
HV signal sampling period
Timer duration for no line detection
Discharge timer duration
OSCILLATOR
Oscillator frequency
Maximum on time for T
J
= 25°C to +125°C
only
Maximum on time
Maximum duty cycle (corresponding to
maximum on time at maximum switching
frequency)
f
OSC
= 65 kHz
f
OSC
= 100 kHz
f
OSC
= 65 kHz
f
OSC
= 100 kHz
f
OSC
= 65 kHz
f
OSC
= 100 kHz
f
OSC
t
ONmax(65kHz)
t
ONmax(100kHz)
t
ONmax(65kHz)
t
ONmax(100kHz)
D
MAX
58
87
11.5
7.5
11.3
7.4
−
65
100
12.3
8.0
12.3
8.0
80
72
109
13.1
8.5
13.1
8.5
−
kHz
ms
ms
%
V
HV(hyst)
T
sample
t
DET
t
DIS
1.5
−
21
21
3.5
1.0
32
32
5
−
43
43
V
ms
ms
ms
V
CC(reg)
V
CC(on)
V
CC(min)
V
CC(off)
V
CC(ovp)
t
VCC(blank)
V
CC(reset)
V
CC(inhibit)
I
CC
1
I
CC
1
I
CC
2
I
CC
2
I
CC3
I
CC4
8
11.0
9.5
8.5
25
−
4.8
0.2
1.3
1.3
1.8
2.3
0.67
0.3
11
12.0
10.5
8.9
26.5
10
7.0
0.8
1.85
1.85
2.6
2.9
0.9
0.6
−
13.0
11.5
9.3
28
−
7.7
1.25
2.2
2.2
3.0
3.5
1.13
0.9
V
V
V
V
V
ms
V
V
mA
5. Internal supply current only, currents sourced via FB pin is not included (current is flowing in GND pin only).
6. Guaranteed by design.
7. CS pin source current is a sum of I
bias
and I
OPC
, thus at V
HV
= 125 V is observed the I
bias
only, because I
OPC
is switched off.
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