© Semiconductor Components Industries, LLC, 2014
December, 2014 − Rev. 2
1 Publication Order Number:
NCP1338/D
NCP1338
PWM Current-Mode
Controller for Free Running
Quasi-Resonant Operation
The NCP1338 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). The
transformer core reset detection is done internally, without using any
external signal, due to the Soxyless concept. The frequency is
internally limited to 130 kHz, preventing the controller from
operating above the 150 kHz CISPR−22 EMI starting limit.
By monitoring the feedback pin activity, the controller enters skip
mode as soon as the power demand falls below a predetermined
level. As each restart is softened by an internal Soft−Skipt, and as
the frequency cannot go below 25 kHz, no audible noise can be
heard.
The NCP1338 also features an efficient protective circuitry 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. Also included is a bulk voltage
monitoring function (known as brown−out protection), an adjustable
overpower compensation, and a V
CC
OVP. The fault timer is reset by
any of these 3 conditions to ensure that the controller immediately
restarts when the condition disappears. Finally, an internal 4.0 ms
soft−start eliminates the traditional startup stress. NCP1338 can be
used in applications where the V
CC
supply voltage is delivered by an
external dc voltage source.
Features
• Free−Running Borderline/Critical Mode Quasi−Resonant Operation
• Current−Mode
• Soft−Skip Mode with Minimum Switching Frequency for Standby
• Auto−Recovery Short−Circuit Protection Independent of Auxiliary
Voltage
• Overvoltage Protection
• Brown−Out Protection
• Two Externally Triggerable Fault Comparators (one for a disable
function, and the other for a permanent latch)
• Internal 4.0 ms Soft−Start
• 500 mA Peak Current Drive Sink Capability
• 130 kHz Max Frequency
• Internal Leading Edge Blanking
• Internal Temperature Shutdown
• Direct Optocoupler Connection
• Dynamic Self−Supply with Levels of 12 V (On) and 10 V (Off)
• SPICE Models Available for TRANsient and AC Analysis
• These are Pb−Free Devices
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.)
PDIP−7
P SUFFIX
CASE 626B
PIN CONNECTIONS
Device Package Shipping†
ORDERING INFORMATION
NCP1338PG PDIP−7
(Pb−Free)
50 Units/Rail
www.onsemi.com
MARKING
DIAGRAM
A = Assembly Location
WL, L = Wafer Lot
YY, Y = Year
WW, W = Work Week
G, G = Pb−Free Package
(Top View)
FB
BO
CS
GND DRV
HV
VCC
NCP1338P
AWL
YYWWG
1
SOIC−7
D SUFFIX
CASE 751U
NCP1338DR2G SOIC−7
(Pb−Free)
2500 Tape & Ree
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specification
Brochure, BRD8011/D.
1
2
3
4
8
6
5
P1338
ALYWG
G
1
8
7
(Note: Microdot may be in either location)
