4/7/2014 1 www.onsemi.com
Test Procedure for the NCP1075PSRGEVB Evaluation Board
Introduction: The NCP1075 Primary Sensed EVAL demo board is a universal input, off-line, 10 watt output,
constant voltage power supply for powering E-meters or white goods applications where tight output voltage regulation is not
necessary. This version of the NCP1075 flyback circuit does not have voltage sensing on the secondary side but utilizes the
aux winding on the primary side of the transformer for sensing an analog of Vout. This eliminates the use of an NCP431 and
optocoupler in the feedback look. This demo board has an output rating of 12 volts at 0.75 amps max.
Equipment Required:
1. Adjustable, isolated AC power source capable of zero to 265 Vac output up to 500 mA. AC source should have the
capability of measuring input power in watts. If not, an AC line analyzer or AC wattmeter should be used.
Wattmeter should be capable if reading down to 50 mW (for standby power measurements.)
2. Digital volt/amp meters to measure output current and voltage to the electronic load.
3. A variable electronic load or rheostat capable of up to a 3 amp load. If an electronic load is used it is preferable to
have a constant resistance load mode. The current meter on the electronic load can be used in lieu of a series, in-line
ammeter.
4. Oscilloscope with probe to monitor output ripple on the demo converter.
Setup Procedure: Set the equipment as shown in the diagram below so that the output voltage and current to the demo board
can be measured and the output ripple can be monitored.
AC Source
Vadj
Iaj
AC out
115 Vac
WATTS
DVM
+
-
volts
DVM
+
-
amps
+
-
AC in
DC out
Board Under Test
(Required if not
in AC source)
+
-
Adj
Electronic
Load
O'scope
Note: Indicated output polarity on above drawing of demo board may not correspond to actual demo board. Please note
output polarity as marked on demo board behind the output terminal strip.