page
date
8 of 9
04/2008
PART NUMBER:
VHK50W
DESCRIPTION:
chassis mount dc-dc converter
15. REMOTE OUTPUT ON/OFF CONTROL
The converter output can be enabled or disabled through the On/Off pin. The control logic is shown in this table. A common control
circuit is shown below.
REM
SW
+Vo
REM (pin 2)
SW
High signal here
disable output
-Vin
-Vo
-Vin (pin 4)
FIGURE 9. REMOTE ON/OFF CONTROL
WITH TRANSISTOR SWITCH
FIGURE 8. REMOTE ON/OFF CONTROL
Logic Table
Negative logic
SW Closed (V
REM
<0.8 V) Output on
SW Open (V
REM
>2.4 V)
Output off
16. ISOLATION
Positive logic
Output off
Output on
The input and output of the converter are electrically isolated. If needed, an output terminal can be connected to an input terminal,
resulting in the converter non-isolated.
17. INPUT FILTERING AND EMI INTERFERENCE
The VHK50W converters have input capacitors that control input current ripple and the associated EMI interference. However, it
has not been tested to a formal standard for conducted emissions. Additional filtering may be needed to ensure compliance to an
EMI standard. Refer to FIGURE 10 for a reference circuit.
L1
C1
C2
FIGURE 10. EMI FILTER FOR VHK50W
L2
C3
+Vin
+Vo
-Vin
CASE
-Vo
C4
VHK50W Series
EMI to meet class A
EMI to meet class B
C1
NC
NC
C2
47µF/50V
ESR<0.60
220µF/50V
ESR<0.120
C3
47µF/50V
ESR<0.60
220µF/50V
ESR<0.120
C4
2200pF/2KV
2200pF/2KV
L1
Short
Short
L2
2.5µH
1.5µH
NOTE: The recommended components are a starting point but not guaranteed for meeting these EMI
requirements.
More or less filtering may be required for a specific application or to meet other EMI standards,
e.g. MIL-STD-461.
20050
SW
112
th
Ave. Tualatin, Oregon
97062
phone
503.612.2300
fax
503.612.2382
CUI [ CUI INC ]
