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AN50 APPLICATION NOTE
20
Input Ripple and Power on Input Rush Current
Note:
Excellent input ripple voltage. Input ripple voltage is recom-
mended to be less than 5% of the output voltage.
Power on Input Rush Current was not measured on the moth-
erboard because we did not want to cut the 5V trace and
insert a current probe in series with the supply. However,
with the input filter design, the Input Rush Current is well
within specification.
I
load
= 9.9A Input Ripple
Voltage = 15mV
Refer to Attach-
ment G for Scope
Picture
Component Case Temperature
Note:
The values for case temperatures are within guidelines. That is, case temperatures for all components should be below
105°C @25°C Ambient.
Device Description
Case Temperature
I
load
= 9.9A
(°C)
Case Temperature
I
load
= 12.4A
(°C)
Case Temperature
I
load
= 13.9A
(°C)
Q3A MOSFET
K1388
57 63 66.3
Q3B MOSFET
K1388
58 64 66.6
L1 Inductor,
Unknown
53 56 61.2
Q2 Schottky Diode
2048CT
66 70 87
IC Raytheon’s RC5050 52 54 58
Cin Input Cap. 1000µF 38.2 36.8 39
Cout Output Cap.
1500µF
35 34.8 38.2
Evaluation Summary
The on-board DC-DC converter is fully functional. It has
excellent load regulation, transient response, and input volt-
age ripple.
Attachment A
Attachment B