page
date
4 of 9
08/2009
PART NUMBER:
VHK75W
DESCRIPTION:
chassis mount dc-dc converter
APPLICATION NOTES
1. OUTPUT DE-RATING
The operating ambient temperature range for VHK75W is -40 ~ +85°C, with the actual output power subject to the following de-rating
curves at free-air convection and at forced air conditions. To ensure long-term reliability, it is important to ensure proper cooling at
the worst operating conditions. Please note the derating curves may improve if the converter is mounted on a metal surface to allow
heat conduction.
VHK75W Power Derating Curves @ Nominal Input
120.00%
Natural
Convection
100.00%
0.5 m/S
(100LFM)
Relative Output Power - % of nominal output
80.00%
1.0 m/S
(200LFM)
1.5 m/S
(300LFM)
60.00%
2.0 m/S
(400LFM)
40.00%
2.5 m/S
(500LFM)
20.00%
3.0 m/S
(600LFM)
3.5 m/S
(700LFM)
0.00%
-40
35
40
45
50
55
60
65
70
75
80
85
Ambient Temperature - degrees C
FIGURE 1. OUTPUT DERATING
2. INPUT VOLTAGE RANGE
It is important to ensure the input voltage measured at the converter input pins is within the range for that converter. Make sure wire
losses and voltage ripples are accounted for. One possible problem is driving the converter with a linear unregulated power supply.
For example, if the average voltage measured by a DMM is 9V, with a voltage ripple of 3Vpp, the actual input can swing from 7.5V to
10.5V. This will be outside the specified input range of 9-36V and the converter may not function properly. On the other end, make
sure the actual input voltage does not exceed the highest voltage of 36V or75V.
3. LEAD WIRES
Make sure the input and output wires are of adequate AWG size to minimize voltage drop, and ensure the voltage across the input
terminals is above the converter's rated minimum voltage at all times. It is recommended to have the wire pairs twisted, respectively
for the input pair and the output pair, so as to minimize noise pickup.
20050
SW
112
th
Ave. Tualatin, Oregon
97062
phone
503.612.2300
fax
503.612.2383
www.v-infinity.com
CUI [ CUI INC ]
