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© Semiconductor Components Industries, LLC, 2010
April, 2010 − Rev. 1
1 Publication Order Number:
AND8454/D
AND8454/D
32 W, 32 V Universal Input
AC-DC Printer Adapter
using the NCP1237
Prepared by: Nicolas Cyr
ON Semiconductor
Introduction
This ac adapter demonstration board targets a printer
adapter application with a 32 V output, and a power
capability of up to 80 W transiently (for 150 ms) and 32 W
permanently. It exceeds the efficiency and standby power
requirements of the US ENERGY STAR® Specification for
External Power supplies (EPS) version 2.0.
It is built around the NCP1237, a fixed-frequency
controller featuring frequency foldback and Soft-Skipt to
maximize efficiency in light load conditions. Additional
functions include dual-level overcurrent protection for
transient peak power, line voltage sensing for Brown-out
protection, as well as overpower compensation to ensure a
constant overload protection independent of the input
voltage (for a detailed description of all these functions and
recommendations on how to use this controller, please refer
to the NCP1237 datasheet and other related documents at
www.onsemi.com.
Specification
The demonstration board must operate across universal
inputs, 85 Vac to 265 Vac (47 Hz to 63 Hz), and supply a
regulated 32 V output capable of delivering 1 A
continuously (32 W), and up to 2.5 A (80 W) for at least
120 ms, as defined in Figure 1. Its average efficiency as
defined by ENERGY STAR should be higher than 87%
(therefore exceeding the EPS 2.0 requirement of 84%), and
its no load input power must be lower than 150 mW. In
addition, the efficiency at an output of 1.0 W must be greater
than 70%. The specification is summarized in Table 1.
Figure 1. Transient Output Current Specification
2.5 A
120 ms
I
OUT
t
1.0 A
2 s
Table 1: Summary of Specifications
Requirement Min Max Unit
Input Voltage 85 265 Vac
Line Frequency 47 63 Hz
Output Voltage 31.5 32.5 Vdc
Output Current − 1.0
(2.5 transient peak for 120 ms)
Adc
Output Power − 32
(80 transient peak for 120 ms)
W
Average Efficiency (as defined by ENERGY STAR) 87 − %
Efficiency at an output power of 1.0 W 70 − %
No Load Input Power − 150 mW
Output Ripple Voltage − ±200 mV
APPLICATION NOTE
http://onsemi.com
