NCP1308 Datasheet, PDF (1/16 Pages) ON Semiconductor – PWM Current−Mode Controller for Free−Running Quasi−Resonant Operation

NCP1308
PWM Current−Mode
Controller for Free−Running
Quasi−Resonant Operation
The NCP1308 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 10 ms
timer prevents the free−run frequency to exceed a high frequency
(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 NCP1308. This feature is particularly useful in
applications where the output voltage varies during operation (e.g.
battery chargers). Thanks 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. If an OVP is detected on
the V_CC pin, 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
• Dynamic Self−Supply Type of V_CC
• Auto−Recovery Overcurrent Protection
• Improved UVLO for V_CC below 10 V
• Latching Overvoltage Protection on V_CC
• 500 mA Peak Current Source/Sink Capability
• Internal 1.0 ms Soft−Start
• Internal 10 ms Minimum T_OFF
• Adjustable Skip Level
• Internal Temperature Shutdown
• Internal Leading Edge Blanking
• Direct Optocoupler Connection
• SPICE Models Available for TRANsient Analysis
• This is a Pb−Free Device
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
SOIC−8
DR SUFFIX
CASE 751
MARKING
DIAGRAM
8
1308
ALYW
G
1
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G = Pb−Free Package
PIN CONNECTIONS
Dmg 1
FB 2
CS 3
GND 4
8 HV
7
6 V_CC
5 Drv
(Top View)
ORDERING INFORMATION
Device
Package
Shipping^†
NCP1308DR2G SOIC−8 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.
© Semiconductor Components Industries, LLC, 2005
1
December, 2005 − Rev. 2
Publication Order Number:
NCP1308/D