NCP1207-D Datasheet, PDF (1/18 Pages) ON Semiconductor – PWM Current-Mode Controller for Free Running Quasi-Resonant Operation

NCP1207
PWM Current−Mode
Controller for Free Running
Quasi−Resonant Operation
The NCP1207 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 NCP1207. 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
• 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
SOIC−8
D1, D2 SUFFIX
CASE 751
MARKING
DIAGRAMS
8
1207
ALYW
1
8
PDIP−8
N SUFFIX
CASE 626
1
1207P
AWL
YYWW
1207/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^†
NCP1207DR2
SOIC−8 2500/Tape & Reel
NCP1207DR2G SOIC−8 2500/Tape & Reel
(Pb−Free)
NCP1207P
PDIP−8
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
June, 2004 − Rev. 6
Publication Order Number:
NCP1207/D