NCP1378 Datasheet, PDF (1/16 Pages) ON Semiconductor – PWM Current-Mode Controller for Free-Running Quasi-Resonant Operation

NCP1378
PWM Current−Mode
Controller for Free−Running
Quasi−Resonant Operation
The NCP1378 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 transformer core reset detection is done through an auxiliary
winding which, brought via a dedicated pin, also enables fast Over
Voltage Protection (OVP). Once an OVP has been detected, the IC
permanently latches off.
The NCP1378 also features an efficient protective circuitry that, in
presence of an overcurrent condition, disables the output pulses and
enters a safe burst mode, trying to restart. Once the default has gone,
the device auto−recovers. Finally an internal 1.0 ms Soft−Start
eliminates the traditional startup stress.
The NCP1378 is tailored for low voltage applications having
UVLO thresholds of 8.4 V (on) and 7.5 V (off).
Features
• Pb−Free Package is Available*
• Free−Running Borderline/Critical Mode Quasi−Resonant Operation
• Latched Overvoltage Protection
• Auto−Recovery Short−Circuit Protection Via UVLO Crossover
• Current−Mode with Adjustable Skip Cycle Capability
• Internal 1.0 ms Soft−Start
• Internal Temperature Shutdown
• Internal Leading Edge Blanking
• 500 mA Peak Current Source/Sink Capability
• External Latch Triggering, e.g. Via Overtemperature Signal
• Direct Optocoupler Connection
• SPICE Models Available for TRANsient Analysis
• Internal 8.0 ms Minimum T_OFF
Typical Applications
• Battery−Based Operations
*For additional information on our Pb−Free strategy and soldering details, please
download the ON Semiconductor Soldering and Mounting Techniques Reference
Manual, SOLDERRM/D.
http://onsemi.com
MARKING
DIAGRAMS
8
1
SOIC−8
D SUFFIX
CASE 751
8
1378
ALYW
1
8
1
PDIP−7
P SUFFIX
CASE 626B
1
1378P
AWL
YYWW
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
6 V_CC
5 Drv
(Top View)
ORDERING INFORMATION
Device
Package
Shipping^†
NCP1378DR2
SOIC−8 2500 Tape & Reel
NCP1378P
PDIP−7
50 Units/Tube
NCP1378PG
PDIP−7
(Pb−Free)
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
October, 2004 − Rev. 1
Publication Order Number:
NCP1378/D