Product Overview

Product Overview
NCP1254: PWM Controller, Current Mode, for Offline Power Supplies
For complete documentation, see the data sheet
Product Description
The NCP1254 is a highly integrated PWM controller capable of delivering a rugged and high performance offline power supply in a
TSOP-6 package. With a supply range up to 35 V, the controller hosts a jittered 65-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 freezing the peak
current setpoint.
To help building rugged converters, the controller features several key protective features: a non-dissipative Over Power
Protection for a constant maximum output current regardless of the input voltage, two latched over voltage protection inputs - either
through a dedicated pin or via the Vcc input and a dual-level auto-recover/latched overload/short-circuit timer.
The controller architecture is designed to authorize a transient peak power excursion when the current setpoint hits the limit. At
this point, the switching frequency is increased form 65 kHz to 130 kHz until the peak event disappears. The timer duration is then
modulated as the converter crosses a peak power excursion mode (long) or undergoes a short circuit (short).
Features
Benefits
• 65kHz Fixed Frequency Current Mode control with 130 kHz
frequency excursion
• Internal and adjustable Over Power Protection (OPP) circuit
• Frequency Foldback down to 26 kHz and Skip-cycle in light
load conditions
• Timer-based Auto-recovery Overload/Short-circuit protection
with 100% to 25% timer reduction for short-circuit faults
• Frequency Jittering in Normal and Frequency Foldback
Modes
• Latch Input
• Double Vcc hiccup in fault mode
Applications
• Allows peak power delivery without growing the transformer
size by temporarily increasing the switching frequency
• Compensates peak current for changing line conditions
• Optimized efficiency across the entire power range
• Robust protection against both overload and short circuit
conditions
• Softened EMI signature
• Flexible input can be used for OVP or OTP protection
• Reduced average power during fault mode
End Products
• Ac-Dc adapters
• Printer Power Supplies
• Notebook Adapters
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
NCP1254ASN65T1G
PPAP
Capable
Active
Flyback
Current
Mode
65
Yes
8.8
Yes
Yes
Yes
35
300 /
500
TSOP-6
Active
Flyback
Current
Mode
65
Yes
8.8
Yes
Yes
Yes
35
300 /
500
TSOP-6
Pb-free
Halide free
NCP1254BSN65T1G
PPAP
Capable
Pb-free
Halide free
Application Diagram
For more information please contact your local sales support at www.onsemi.com
Created on: 6/30/2016