Product Overview

Product Overview
NCP1251: PWM Controller, Current Mode, for Offline Power Supplies
For complete documentation, see the data sheet
Product Description
The NCP1251 is a highly integrated PWM controller capable of delivering a rugged and high performance offline power supply in a
tiny TSOP-6 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 no-load 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, an auto-recovery OVP also monitors the Vcc line. These features offer an efficient protection in case of optocoupler
failure or adverse open loop operation.
Finally, a timer-based short-circuit 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
Benefits
• Non-dissipative internal and adjustable Over Power
Protection (OPP)
• Frequency Foldback down to 26 kHz and Skip-Cycle in light
load conditions
• Internal Ramp Compensation
• Frequency jittering from full load to skip-cycle
• Latch input for OVP and OTP implementations
• Over Voltage Protection (OVP) monitoring on the Vcc pin
• Limits maximum delivered power without affecting standby
performance
• High efficiency in light load conditions
•
•
•
•
Reduces the number of external components
Improved EMI performance
Simple implementation of required protection functions
Protects against output over voltage conditions without any
added components
• See NCP1250 for no Over Voltage Protection (OVP) on the
Vcc pin
Applications
End Products
• Offline Adapters
• AC-DC converters
• 45W Adapter
• Set-top Boxes
• Printers
• Notebooks and Netbooks
Part Electrical Specifications
Product
Compliance
Status
Topolog
y
Control
Mode
fsw Typ
(kHz)
StandUVLO
by Mode (V)
Short
Circuit
Protecti
on
Latch
Soft
Start
VCC Max Drive
(V)
Cap.
(mA)
Packag
e Type
NCP1251ASN100T1G
Pb-free
Active
Flyback
Current
Mode
100
Yes
8.8
Yes
Yes
Yes
28
300 /
500
TSOP-6
Active
Flyback
Current
Mode
65
Yes
8.8
Yes
Yes
Yes
28
300 /
500
TSOP-6
Active
Flyback
Current
Mode
100
Yes
8.8
Yes
OVP
Yes
28
300 /
500
TSOP-6
Active
Flyback
Current
Mode
65
Yes
8.8
Yes
OVP
Yes
28
300 /
500
TSOP-6
Active
Flyback
Current
Mode
65
Yes
8.8
Yes
NO
Yes
28
300 /
500
TSOP-6
Active
Flyback
Current
Mode
65
Yes
8.8
Yes
Yes
Yes
28
300 /
500
TSOP-6
Halide free
NCP1251ASN65T1G
Pb-free
Halide free
NCP1251BSN100T1G
Pb-free
Halide free
NCP1251BSN65T1G
Pb-free
Halide free
NCP1251CSN65T1G
Pb-free
Halide free
NCP1251FSN65T1G
Pb-free
Halide free
Application Diagram
For more information please contact your local sales support at www.onsemi.com
Created on: 6/30/2016