NCP1217 Datasheet, PDF (1/18 Pages) ON Semiconductor – Enhanced PWM Current-Mode Controller for High-Power Universal Off-Line Supplies

NCP1217, NCP1217A
Enhanced PWM Current−Mode
Controller for High−Power
Universal Off−Line Supplies
Housed in an SO−8 or PDIP−7 package, the NCP1217 represents
the enhanced version of the NCP1203−based controllers. Thanks to its
high drive capability, NCP1217 drives large gate−charge MOSFETs,
which together with internal ramp compensation and built−in
overvoltage protection, ease the design of modern AC/DC adapters.
NCP1217 offers a true alternative to UC384X−based designs.
With an internal structure operating at different fixed frequencies
(65–100–133 kHz), the controller features a high−voltage startup FET,
which ensures a clean and loss less startup sequence. Its current−mode
control topology provides an excellent input audio−susceptibility and
inherent pulse−by−pulse control. Internal ramp compensation easily
prevents subharmonic oscillations from taking place in continuous
conduction mode designs.
When the current setpoint falls below a given value, e.g. the output
power demand diminishes, the IC automatically enters the so−called
skip cycle mode and provides excellent efficiency at light loads.
Because this occurs at a user adjustable low peak current, no acoustic
noise takes place.
The NCP1217 features two efficient protective circuitries: 1) In
presence of an overcurrent condition, the output pulses are disabled
and the device enters a safe burst mode, trying to restart. Once the
default has gone, the device auto−recovers. 2) If an external signal
(e.g. a temperature sensor) pulls Pin 1 above 3.2 V, output pulses are
immediately stopped and the NCP1217 stays latched in this position.
Reset occurs when the V_CC collapses to ground, e.g. the user unplugs
the power supply.
Features
• Current−Mode with Adjustable Skip−Cycle Capability
• Built−in Internal Ramp Compensation
• Auto−Recovery Internal Output Short−Circuit Protection
• Internal 1.0 ms Soft−Start (A Version Only)
• Limited Duty−Cycle to 50% (A Version Only)
• Full Latchoff if Adjustment Pin is Brought High
• Extremely Low No−Load Standby Power
• Internal Temperature Shutdown
• 500 mA Peak Current Capability
• Fixed Frequency Versions at 65 kHz, 100 kHz and 133 kHz
• Direct Optocoupler Connection
• Internal Leading Edge Blanking
• SPICE Models Available for TRANsient and AC Analysis
• Pb−Free Packages are Available
Typical Applications
• High Power AC/DC Converters for TVs, Set−Top Boxes, etc.
• Offline Adapters for Notebooks
• Telecom DC−DC Converters
• All Power Supplies
http://onsemi.com
MINIATURE PWM
CONTROLLER FOR HIGH
POWER AC/DC WALL
ADAPTERS AND OFFLINE
BATTERY CHARGERS
8
1
SO−8
D SUFFIX
CASE 751
MARKING
DIAGRAMS
8
17XXX
ALYW
1
8
1
PDIP−7
P SUFFIX
CASE 626B
P1217XXXX
AWL
YYWW
1
XXXX = Specific Device Code*
A
= Assembly Location
WL, L = Wafer Lot
YY, Y = Year
WW, W = Work Week
*DEVICE MARKING INFORMATION
See detailed device marking information in the ordering
information section on page 16 of this data sheet.
PIN CONNECTIONS
Adj 1
FB 2
CS 3
Gnd 4
8 HV
7 NC
6 V_CC
5 Drv
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information in the ordering
information section on page 16 of this data sheet.
© Semiconductor Components Industries, LLC, 2004
1
July, 2004 − Rev. 3
Publication Order Number:
NCP1217/D