NCP1240
Fixed Frequency Current
Mode Controller for Flyback
Converters
The NCP1240 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. This HV structure allows
the brown−out detection as well.
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
40Xfff
ALYWX
G
1
SOIC−7
CASE 751U
40Xfff = Specific Device Code
X = A, B, E or F
fff = 065 or 100
A
= Assembly Location
L
= Wafer Lot
Y
= Year
W
= Work Week
G
= Pb−Free Package
PIN CONNECTIONS
Latch 1
FB 2
8
HV
•
Fixed−Frequency Current−Mode Operation (65 kHz and 100 kHz
•
•
•
•
•
•
•
•
•
•
•
•
•
These Devices are Pb−Free and Halogen Free/BFR Free
frequency options)
6 V
CC
CS 3
Frequency Foldback then Skip Mode for Maximized Performance in
GND 4
5 DRV
Light Load and Standby Conditions
(Top View)
Timer−Based Overload Protection with Latched (Options A and E) or
Auto−Recovery (Options B and F) Operation
High−voltage Current Source with Brown−Out Detection and
ORDERING INFORMATION
See detailed ordering and shipping information on page 44 of
Dynamic Self−Supply, Simplifying the Design of the V
CC
Circuitry
this data sheet.
Frequency Modulation for Softened EMI Signature
Adjustable Overpower Protection Dependant on the Bulk Voltage
Latch−off Input Combined with the Overpower Protection Sensing
Input
V
CC
Operation up to 28 V, With Overvoltage Detection
Typical Applications
500/800 mA Source/Sink Drive Peak Current
•
AC−DC Adapters for Notebooks, LCD, and Printers
Capability
•
Offline Battery Chargers
10 ms Soft−Start
•
Consumer Electronic Power Supplies
Internal Thermal Shutdown
•
Auxiliary/Housekeeping Power Supplies
No−Load Standby Power < 30 mW
•
Offline Adapters for Notebooks
X2 Capacitor in EMI Filter Discharging Feature
©
Semiconductor Components Industries, LLC, 2015
1
July, 2015 − Rev. 1
Publication Order Number:
NCP1240/D
NCP1240
TYPICAL APPLICATION EXAMPLE
RCLAMP
CCLAMP
CBULK
+
D6
D7
1 TR
W1
dc output
COUT
RLOAD
R2
GND
R1
12 L2
ac input
34
CX2
12 L1
CX1
34
D4
D5
D2
D9
D10
RHV
D8
IC1
1 LATCH
2 FB
NTC
3 CS
4 GND
GND
HV 8
VCC 6
DRV 5
GND
D3
C1
3
2
5
W3
W2
D1
+
R3
IC2
NCP431
GND
1
2
R4
4
GND
C4
GND
Q1
6
GND
GND GND
GND
NCP1240
ROPP
RSENSE
GND
OK1
4
C2
3
PC817
GND
GND
C3
Figure 1. Flyback Converter Application Using the NCP1240
OPTIONS
Part
Option
A
A
B
NCP1240
B
E
F
100 kHz
65 kHz
65 kHz
Autorecovery
Latched
Autorecovery
Frequency
65 kHz
100 kHz
65 kHz
OCP Fault
Latched
Latched
Autorecovery
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, brown−out detection 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
NCP1240
SIMPLIFIED INTERNAL BLOCK SCHEMATIC
Vdd
Intc
Intc
Vhv DC sample
HV
Brown_Out
OVP_CMP
50 us
Filter
Vovp
2.5V
OVP
AC_Off
VccOVP_CMP
VccOVP
OTP_CMP
10 us
Filter
26V
SG & X2 & Vcc
VccOVP
TSD
Vcc_Int
Vcc regulator
control
Dual HV
Start−up
current source
8 mA
LATCH
Vclamp Rclamp
350 us
Filter
Votp
0.4V
1k
OTP
VCC
1.2V
UVLO_CMP
UVLO
VccOFF
ICstartB
Vdd reg
SS_end
Set
Brown_Out
Q
Latch
ON_CMP
Reset Qb
VccON
VccON
Vdd
PowerOnReset_CMP
RESET
VccRESET
VCC
Clamp
RESET
12V
5V
3.0V
freq folback
CSref
FBbuffer
Skip_CMP
1.4V
SkipB
4uMho
PFM input
Ramp_OTA
Vramp_offset
Saw output
STOP_CMP
VccMIN
VCC
VccMIN
8.4V
5uA
Off_mode_CMP1
Set
2.2V
Q
ICstart
Von
Reset Qb
Off_mode_CMP2
GoToOffMode timer 500ms
0.8V
jittering
FM input
Square output
OSC 65kHz
ton_max output
Voff
Vfb(reg)
FB
Internal resitance 40k
Rfb1
Vskip
MAX_ton
Vhv DC sample
Division ratio 4
Rfb3
Rfb2
DRV
PWM_CMP
PWM
Reset
Brown_OutB
Qb
IC stopB
Set
Q
Vfb(opc)
SoftStart_CMP
V to I
Iopc = 0.5u*(Vhv−125)
Enable
Vdd
1uA
Itran_CMP
Itran
Vcs(tran)
0.5V
Set
Q
Transient timer up/down
Fault
Soft Start timer
SS_end
CS
Reset
Qb
Ilimit_CMP
MAX_ton
Ilimit
LatchB
FaultB
Set
Q
Fault timer
Fault
RESET
IC stop
Vilim
0.7V
GND
Autorecovery timer
CSstop_CMP
LEB 120ns
4 events timer
VCSstop
1.05V
Brown_Out
TSD
TSD
Figure 2. Simplified Internal Block Schematic
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3
Latch management
Reset
Qb
Latch
Vcc(reg)
10.8V
9.3V
NCP1240
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
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
°C/W
°C
°C
V
V
Unit
V
mA
V
mA
V
mA
V
mA
°C/W
R
qJ−C
T
JMAX
T
STRGMAX
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
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.
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
(X2 discharge current value is equal to I
start2
)
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 (Note 5)
Overvoltage Threshold
5.
6.
7.
8.
V
CC(reg)
V
CC(on)
V
CC(min)
V
CC(off)
V
CC(ovp)
8
11.0
7.8
8.8
25
11
12.0
8.4
9.3
26.5
−
13.0
9.0
9.8
28
V
V
V
V
V
V
CC(off)
< V
CC(min)
with the minimum gap 0.5 V.
Internal supply current only, currents sourced via FB pin is not included (current is flowing in GND pin only).
Guaranteed by design.
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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NCP1240
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
SUPPLY
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 6)
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)
BROWN−OUT
Brown−Out Thresholds
Timer Duration for Line Cycle Drop−out
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)
Frequency Jittering Amplitude, in Percentage
of F
OSC
Frequency Jittering Modulation Frequency
FREQUENCY FOLDBACK
Feedback Voltage Threshold Below Which
Frequency Foldback Starts
Feedback Voltage Threshold Below Which
Frequency Foldback is Complete
Minimum Switching Frequency
(NCP1240A/B)
(NCP1240E/F)
5.
6.
7.
8.
T
J
= 25°C
T
J
= 25°C
V
FB
= V
skip(in)
+ 0.1
V
FB(foldS)
V
FB(foldE)
f
OSC(min)
23
21
27
27
32
32
2.35
1.4
2.5
1.5
2.6
1.6
V
V
kHz
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
−
43
43
3.5
1.0
64
64
5
−
86
86
V
ms
ms
ms
V
HV
going up
V
HV
going down
V
HV(start)
V
HV(stop)
t
HV
102
94
35
111
103
50
120
112
75
V
ms
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
−
4.8
0.2
1.3
1.3
1.8
2.0
0.5
0.35
10
7.0
0.8
1.85
1.85
2.6
2.9
0.65
0.5
−
7.7
1.25
2.2
2.2
3.0
3.2
0.8
0.7
ms
V
V
mA
Test Condition
Symbol
Min
Typ
Max
Unit
A
jitter
F
jitter
±3
85
±5.5
125
±8
165
%
Hz
V
CC(off)
< V
CC(min)
with the minimum gap 0.5 V.
Internal supply current only, currents sourced via FB pin is not included (current is flowing in GND pin only).
Guaranteed by design.
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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