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NCP1251_15 Datasheet, PDF (1/24 Pages) ON Semiconductor – Current-Mode PWM Controller for Off-line Power Supplies | |||
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NCP1251
Current-Mode PWM
Controller for Off-line
Power Supplies
The NCP1251 is a highly integrated PWM controller capable of
delivering a rugged and high performance offline power supply in a
tiny TSOPâ6 package. With a supply range up to 28 V, the controller
hosts a jittered 65 kHz or 100 kHz switching circuitry operated in peak
current mode control. When the power on the secondary side starts to
decrease, the controller automatically folds back its switching
frequency down to a minimum level of 26 kHz. As the power further
goes down, the part enters skip cycle while limiting the peak current.
Over Power Protection (OPP) is a difficult exercise especially when
noâload standby requirements drive the converter specifications. The
ON proprietary integrated OPP lets you harness the maximum
delivered power without affecting your standby performance simply
via two external resistors. A latched Over Voltage Protection (OVP) is
combined on the same pin. For ease of implementation, a latched OVP
also monitors the VCC line. They offer an efficient protection in case
of optocoupler destruction or adverse open loop operation.
Finally, a timerâbased shortâcircuit protection offers the best
protection scheme, letting you precisely select the protection trip point
irrespective of a loose coupling between the auxiliary and the power
windings.
Features
⢠FixedâFrequency 65 or 100 kHz CurrentâMode Control Operation
⢠Internal and Adjustable Over Power Protection (OPP) Circuit
⢠Frequency Foldback Down to 26 kHz and SkipâCycle in Light Load
Conditions
⢠Internal Ramp Compensation
⢠Internal Fixed 4 ms SoftâStart
⢠100 ms TimerâBased AutoâRecovery ShortâCircuit Protection
⢠Frequency Jittering in Normal and Frequency Foldback Modes
⢠Option for AutoâRecovery or Latched ShortâCircuit Protection
⢠OVP Input for Improved Robustness
⢠Up to 28 V VCC Operation
⢠Latched or AutoâRecovery OVP Protection on VCC
⢠+300 mA / â500 mA Source/Sink Drive Capability
⢠Less than 100 mW Standby Power at High Line
⢠EPS 2.0 Compliant
⢠These are PbâFree Devices
Typical Applications
⢠acâdc Converters for TVs, Setâtop Boxes and Printers
⢠Offline Adapters for Notebooks and Netbooks
www.onsemi.com
MARKING
DIAGRAM
TSOPâ6
(SOT23â6)
5xyAYWG
SN SUFFIX
G
1
CASE 318G
1
STYLE 13
5xy = Specific Device Code
x
= A or U
y
= A, 2, C, D, or F
A
= Assembly Location
Y
= Year
W
= Work Week
G
= PbâFree Package
(Note: Microdot may be in either location)
PIN CONNECTIONS
GND 1
6 DRV
FB 2
OPP/Latch 3
5 VCC
4 CS
(Top View)
ORDERING INFORMATION
See detailed ordering, marking and shipping information on
page 2 of this data sheet.
© Semiconductor Components Industries, LLC, 2015
1
June, 2015 â Rev. 14
Publication Order Number:
NCP1251/D
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