EP-91 12 V, 1 A, Universal Input Supply
7-Feb-2006
14 Audible Noise
An open-frame (no enclosure) unit was tested with an Audio Precision Analyzer, using a
microphone positioned one inch from the core of transformer T1. The test was done with
the unit in an acoustically isolated and dampened chamber. The load was adjusted until
a maximum reading was obtained.
35 dBrA is considered the acceptable limit for frequencies below 18 kHz. An enclosure
will typically further reduce measurable acoustic noise levels by an additional 10 dBrA.
Audio Precision
08/17/05 15:04:17
Audio Precision
08/17/05 15:11:39
+80
+70
+60
+80
+70
+60
+50
+50
+40
+40
d
B
r
d
B
r
+30
+30
+20
A
+20
A
+10
+10
+0
+0
-10
-20
-10
-20
-30
0
-30
2k
4k
6k
8k
10k
12k
14k
16k
18k
20k
22k
0
2k
4k
6k
8k
10k
12k
14k
16k
18k
20k
22k
Hz
Hz
Color
Line Style Thick Data
Axis
Color
Line Style Thick Data
Axis
Green Solid
1
Fft.Ch.1 Ampl Left
Green Solid
1
Fft.Ch.1 Ampl Left
Arts_audionoise1.at2
Arts_audionoise1.at2
Figure 29 – Audible Noise VIN = 120 VAC;
Figure 30 – Audible Noise VIN = 120 VAC;
IOUT = 350 mA.
IOUT = 1 A.
Audio Precision
08/17/05 15:09:38
Audio
08/17/05
+80
+80
+70
+60
+50
+70
+60
+50
+40
+30
+20
+10
+0
+40
d
B
r
d
B
r
+30
+20
A
A
+10
+0
-10
-10
-20
-20
-30
0
-30
0
2k
4k
6k
8k
10k
12k
14k
16k
18k
20k
22k
2k
4k
6k
8k
10k
12k
14k
16k
18k
20k
22k
Hz
Hz
Color
Line Style
Thick Data
Axis
Left
Color
Line Style Thick Data
Axis
Green Solid
1
Fft.Ch.1 Ampl
Green Solid
1
Fft.Ch.1 Ampl Left
Arts_audionoise1.at2
Arts_audionoise1.at2
Figure 31 – Audible Noise VIN = 230 VAC;
Figure 32 – Audible Noise VIN = 230 VAC;
IOUT =1 A.
IOUT =1.2 A.
Note: Shaded area obscured due to ambient noise.
Power Integrations
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www.powerint.com
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