NCP1207A_07 Datasheet, PDF (1/17 Pages) ON Semiconductor – PWM Current-Mode Controller for Free Running Quasi-Resonant Operation

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 V_CC 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 V_CC 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 V_CC Below 10 V
•ăInternal 1.0 ms Soft-Start
•ăInternal 8.0 ms Minimum T_OFF for NCP1207A,
4.5 ms Minimum T_OFF for NCP1207B
•ăAdjustable Skip Level
•ăInternal Temperature Shutdown
•ăDirect Optocoupler Connection
•ăSPICE Models Available for TRANsient Analysis
•ăPb-Free Packages are Available
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.)
©Ă Semiconductor Components Industries, LLC, 2007
1
November, 2007 - Rev. 8
http://onsemi.com
8
1
8
1
SOIC-8
D SUFFIX
CASE 751
SOIC-7
D SUFFIX
CASE 751U
MARKING
DIAGRAM
8
1207A
ALYW
G
1
8
1207B
ALYW
G
1
8
8
1
PDIP-8
P SUFFIX
CASE 626
1207AP
AWL
YYWWG
1
1207A/B/AP = Device Code
A
= Assembly Location
L, WL
= Wafer Lot
Y, YY
= Year
W, WW
= Work Week
G or G
= Pb-Free Package
PIN CONNECTIONS
Dmg 1
FB 2
CS 3
GND 4
8 HV
7 NC
6 V_CC
5 Drv
ORDERING INFORMATION
Device
Package
Shipping^†
NCP1207ADR2 SOIC-8 2500/Tape & Reel
NCP1207ADR2G SOIC-8 2500/Tape & Reel
(Pb-Free)
NCP1207AP
PDIP-8
50 Units / Rail
NCP1207APG
PDIP-8
(Pb-Free)
50 Units / Rail
NCP1207BDR2G SOIC-7 2500/Tape & Reel
(Pb-Free)
†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