NCP1377, NCP1377B
PWM Current−Mode
Controller for Free−Running
Quasi−Resonant Operation
The NCP1377 combines a true current mode modulator and a
demagnetization detector which ensures full borderline/critical
Conduction Mode in any load/line conditions together with
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
NCP1377, 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. For
NC1377B, the internal timer duration is reduced to 3.0
ms
to allow
operation at higher frequencies (up to 300 kHz).
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 1377 features a sampling time of
4.5
ms
whereas it is 1.5
ms
for the B version.
The NCP1377 also features an efficient protective circuitries
which, 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.
Features
http://onsemi.com
MARKING DIAGRAMS
8
1
SOIC−8
DR SUFFIX
CASE 751
1
8
1377
ALYW
G
1
8
1377B
ALYW
G
8
1
SOIC−7
D1 SUFFIX
CASE 751U
8
377D1
ALYW
G
G
1
8
1
PDIP−7
P SUFFIX
CASE 626B
1
1377P
AWL
YYWWG
1
1377BP
AWL
YYWWG
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Free−Running Borderline/Critical Mode Quasi−Resonant Operation
Latched Overvoltage Protection
Auto−Recovery Short−Circuit Protection Via UVLO Crossover
External Latch Triggering, e.g. Via Overtemperature Signal
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
Under Voltage Lockout Level of 12.5 V (On) and 7.5 V (Min)
Direct Optocoupler Connection
SPICE Models Available for TRANsient Analysis
Internal Minimum T
OFF
Pb−Free Packages are Available
A
= Assembly Location
L, WL = Wafer Lot
Y, YY = Year
W, WW = Work Week
G
or G = Pb−Free Package
(Note: Microdot may be in either location)
PIN CONNECTIONS
Dmg 1
FB 2
CS 3
GND 4
(Top View)
6 V
CC
5 Drv
8 HV
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.)
1
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 14 of this data sheet.
©
Semiconductor Components Industries, LLC, 2006
October, 2006
−
Rev. 7
Publication Order Number:
NCP1377/D
ONSEMI [ ON SEMICONDUCTOR ]
