NCP1207A, NCP1207B
PWM Current-Mode
Controller for Free Running
Quasi-Resonant Operation
The NCP1207A/B combines a true current mode modulator and a
demagnetization detector to ensure full borderline/critical Conduction
Mode in any load/line conditions and minimum drain voltage switching
(Quasi-Resonant operation). Due to its inherent skip cycle capability,
the controller enters burst mode as soon as the power demand falls
below a predetermined level. As this happens at low peak current, no
audible noise can be heard. For the NCP1207A, an internal 8.0 ms timer
prevents the free-run frequency to exceed 125 kHz (therefore below the
150 kHz CISPR-22 EMI starting limit), while the skip adjustment
capability lets the user select the frequency at which the burst foldback
takes place. For the NCP1207B, the internal timer duration is reduced to
4.5 ms to allow operation at higher frequencies (up to 200 kHz).
The Dynamic Self-Supply (DSS) drastically simplifies the
transformer design in avoiding the use of an auxiliary winding to
supply the NCP1207A/B. This feature is particularly useful in
applications where the output voltage varies during operation (e.g.
battery chargers). Due to its high-voltage technology, the IC is
directly connected to the high-voltage DC rail. As a result, the
short-circuit trip point is not dependent upon any VCC auxiliary level.
The transformer core reset detection is done through an auxiliary
winding which, brought via a dedicated pin, also enables fast
Overvoltage Protection (OVP). Once an OVP has been detected, the
IC permanently latches off.
Finally, the continuous feedback signal monitoring implemented
with an overcurrent fault protection circuitry (OCP) makes the final
design rugged and reliable.
•ăFree-Running Borderline/Critical Mode Quasi-Resonant Operation
•ăCurrent-Mode with Adjustable Skip-Cycle Capability
•ăNo Auxiliary Winding VCC Operation
•ăAuto-Recovery Overcurrent Protection
•ăLatching Overvoltage Protection
•ăExternal Latch Triggering, e.g. Via Overtemperature Signal
•ă500 mA Peak Current Source/Sink Capability
•ăUndervoltage Lockout for VCC Below 10 V
•ăInternal 1.0 ms Soft-Start
•ăInternal 8.0 ms Minimum TOFF for NCP1207A,
4.5 ms Minimum TOFF for NCP1207B
•ăAdjustable Skip Level
•ăInternal Temperature Shutdown
•ăDirect Optocoupler Connection
•ăSPICE Models Available for TRANsient Analysis
•ăPb-Free Packages are Available
http://onsemi.com
MARKING
DIAGRAM
8
1
©Ă Semiconductor Components Industries, LLC, 2007
November, 2007 - Rev. 8
1
1
8
1207B
ALYW
G
SOIC-7
D SUFFIX
CASE 751U
8
1
1
8
PDIP-8
P SUFFIX
CASE 626
8
1207AP
AWL
YYWWG
1
1
1207A/B/AP
A
L, WL
Y, YY
W, WW
G or G
= Device Code
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb-Free Package
PIN CONNECTIONS
Dmg
1
8
HV
FB
2
7
NC
CS
3
6
VCC
GND
4
5
Drv
ORDERING INFORMATION
Package
Shipping†
SOIC-8
2500/Tape & Reel
SOIC-8
(Pb-Free)
2500/Tape & Reel
PDIP-8
50 Units / Rail
NCP1207APG
PDIP-8
(Pb-Free)
50 Units / Rail
NCP1207BDR2G
SOIC-7
(Pb-Free)
2500/Tape & Reel
Device
NCP1207ADR2
NCP1207ADR2G
NCP1207AP
Typical Applications
•ăAC/DC Adapters for Notebooks, etc.
•ăOffline Battery Chargers
•ăConsumer Electronics (DVD Players, Set-Top Boxes, TVs, etc.)
•ăAuxiliary Power Supplies (USB, Appliances, TVs, etc.)
1207A
ALYW
G
SOIC-8
D SUFFIX
CASE 751
8
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specifications
Brochure, BRD8011/D.
Publication Order Number:
NCP1207A/D
