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© Semiconductor Components Industries, LLC, 2012
October, 2012 − Rev. 4
1 Publication Order Number:
EVBUM2145/D
NCP1271ADAPGEVB
19 V, 3.0 A Universal Input
AC-DC Adaptor Using
NCP1271 Evaluation Board
User's Manual
Introduction
The NCP1271 is one of the latest fixed−frequency
current−mode PWM switching controllers with
(1) adjustable Soft−Skipt standby operation for low−level
audible noise, (2) integrated high−voltage startup for saving
standby power, (3) timer based overload fault detection, and
(4) internal latch protection features. Table 1 summarizes all
the features of an NCP1271 based power supply.
This evaluation board user’s manual presents an example
circuit (Figure 2) using the NCP1271 (65 kHz version) in a
flyback topology. The design steps and subsequent
measurements are also included. An Excel based design
worksheet is available at www.onsemi.com.
The measurements show that the 19 V, 3.0 A circuit
delivers above 85% across a universal input (85 to 265 Vac).
The no load standby consumption is 83 mW at 230 Vac and
the light load operation is greater than 75% efficient.
Figure 1. Evaluation Board Photo
Figure 2. Evaluation Board Schematic
IC1 NCP1271A
+
−
85 to
265 Vac
19 V / 3 A
Common
Mode Choke
D8 MBR3100
R1 100k / 2W
R5 30.1k
E3506−A
D6 MRA4005T3
1N5406 x 4
D7 MURS160
R7 511
R9 1.69k
C3 82uF / 400V
IC4 TL431
Q1 SPP06N80C3
0.25 / 1W
D5 MMSZ914
C4 100uF
R2 10
D10 MZP4746A (18V)
R10 1.69k
C9 2200 uF
C10 2200 uF
R6 10
IC3 SFH615AA−X007
C5 10 nF
Flyback transformer :
Cooper CTX22−17179
Lp = 180uH, leakage 2.5uH max
np : ns : naux = 30 : 6 : 5
Hi−pot 3600Vac for 1 sec, primary to secondary
Hi−pot 8500Vac for 1 sec, winding to core
C12
0.15 uF
C7 1.2 nF
C6 1.2 nF
C2 0.1 uF
T1
C1 0.1 uF
D1 − D4
R12 2.37k
R11 15.8k
C11 1nF/ 1000V
R8
Fuse 2A
C13 100uF
http://onsemi.com
EVAL BOARD USER’S MANUAL
