© Semiconductor Components Industries, LLC, 2005
September, 2005 − Rev. 3
1 Publication Order Number:
NCP1212/D
NCP1212
Current Mode PWM
Controller for Both Forward
and Flyback Converters
NCP1212 is a high performance current mode PWM controller
specifically designed for off−line and DC−to−DC converter
applications. The device requires very few external components and
offers designer additional protection for better system reliability. The
device features a trimmed oscillator for precise Duty Cycle control,
accurate bandgap voltage reference, high gain error amplifier, current
sensing comparator and a high current totem pole output gate driver
that ideally drives the external power MOSFET. Additionally, the
device has built−in programmable Brownout Detect and Soft−Start
features to enhance system reliability. Also, the 48%/82% selectable
maximum turn on Duty Cycle control and external programmable
switching frequency capabilities make this device an ideal controller
for both forward and flyback configurations. This device is available
in both PDIP−8 and space saving SOIC−8 packages.
Features
• Trimmed Oscillator Charge and Discharge Current for Precise Duty
Cycle Control
• Internal High Accuracy Bandgap Voltage Reference
• Current Mode Operation up to 200 kHz
• Inherent Feed Forward Compensation
• Latching PWM for Cycle−by−Cycle Current Limiting
• High Current Totem Pole Output Gate Driver
• Low Startup and Operating Current
• Internal Undervoltage Lockout with Hysteresis
• Internal Leading Edge Blanking for Current Feedback
• Direct Interface with Optocoupler for Secondary Sensing
• Built−in Soft−Start Function, Programmable by External Capacitor
• User Programmable 48%/82% Maximum Duty Cycle Selection
• Output Overvoltage Protection Against Open Loop
• AC Line Brownout Detect Protection
• Output Overload Protection Irrespective of Auxiliary Voltage Level
• Pb−Free Packages are Available
Typical Applications
• ATX PC Power Supply
• Universal Input Wall Mount Adaptors
• CRT Monitor
• All Flyback and Forward SMPS Systems
MARKING
DIAGRAM
A = Assembly Location
L, WL = Wafer Lot
Y, YY = Year
W, WW = Work Week
G = Pb−Free Package
G = Pb−Free Package
http://onsemi.com
PDIP−8
N SUFFIX
CASE 626
1
8
1
8
SOIC−8
DSUFFIX
CASE 751
NCP1212
AWL
YYWWG
1
8
Device Package Shipping
†
ORDERING INFORMATION
NCP1212DR2 SOIC−8 2500/Tape & Ree
NCP1212P PDIP−8 50 Units / Rail
NCP1212DR2G SOIC−8
(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.
N1212
ALYW
G
1
8
NCP1212PG PDIP−8
(Pb−Free)
50 Units / Rail
18
5
3
4
(Top View)
FB
CS
SS/DMAX
PIN CONNECTIONS
7
6
2
VCC
BOK
CT
GND
DRV
