NCP1207A Datasheet, PDF (1/16 Pages) ON Semiconductor – PWM Current-Mode Controller for Free Running Quasi-Resonant Operation

NCP1207A
PWM Current−Mode
Controller for Free Running
Quasi−Resonant Operation
The NCP1207A 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. An internal 8.0 ms timer prevents the
free−run frequency to exceed 100 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.
The Dynamic Self−Supply (DSS) drastically simplifies the
transformer design in avoiding the use of an auxiliary winding to
supply the NCP1207A. 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.
Features
• Free−Running Borderline/Critical Mode Quasi−Resonant Operation
• Current−Mode with Adjustable Skip−Cycle Capability
• No Auxiliary Winding V_CC Operation
• Auto−Recovery Overcurrent Protection
• Latching Overvoltage Protection
• External Latch Triggering, e.g. Via Overtemperature Signal
• 500 mA Peak Current Source/Sink Capability
• Undervoltage Lockout for VCC Below 10 V
• Internal 1.0 ms Soft−Start
• Internal 8.0 ms Minimum T_OFF
• Adjustable Skip Level
• Internal Temperature Shutdown
• Direct Optocoupler Connection
• SPICE Models Available for TRANsient Analysis
• Pb−Free Package is Available
Typical Applications
• AC/DC Adapters for Notebooks, etc.
• Offline Battery Chargers
• Consumer Electronics (DVD Players, Set−Top Boxes, TVs, etc.)
• Auxiliary Power Supplies (USB, Appliances, TVs, etc.)
http://onsemi.com
8
1
8
1
MARKING
DIAGRAMS
8
SO−8
D1, D2 SUFFIX
CASE 751
1207A
ALYW
1
8
PDIP−8
N SUFFIX
CASE 626
1
1207AP
AWL
YYWW
1207A/P = Device Code
A
= Assembly Location
WL, L = Wafer Lot
YY, Y = Year
WW, W = Work Week
PIN CONNECTIONS
Dmg 1
FB 2
CS 3
Gnd 4
8 HV
7 NC
6 V_CC
5 Drv
(Top View)
ORDERING INFORMATION
Device
Package
Shipping^†
NCP1207ADR2 SOIC−8 2500/Tape & Reel
NCP1207ADR2G
NCP1207AP
SOIC−8
(Pb−Free)
PDIP−8
2500/Tape & Reel
50 Units/Tube
†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.
© Semiconductor Components Industries, LLC, 2004
1
November, 2004 − Rev. 1
Publication Order Number:
NCP1207A/D