JFC050C Datasheet, PDF (10/20 Pages) Tyco Electronics – dc-dc Converters; 18 to 36 Vdc Input; 15 Vdc Output; 50 W to 100 W

JFC050C, JFC075C, JFC100C Power Modules:
dc-dc Converters; 18 to 36 Vdc Input, 15 Vdc Output; 50 W to 100 W
Data Sheet
October 1999
Feature Descriptions (continued)
Remote On/Off (continued)
For remote-sense operation with multiple paralleled
units, see Forced Load Sharing (Parallel Operation)
section.
If not using the remote-sense feature to regulate the
output at the point of load, then connect SENSE(+) to
VO(+) and SENSE(–) to VO(–) at the module.
Although the output voltage can be increased by both
the remote sense and by the trim, the maximum
increase for the output voltage is not the sum of both.
The maximum increase is the larger of either the
remote sense or the trim. Consult the factory if you
need to increase the output voltage more than the
above limitation.
The amount of power delivered by the module is
defined as the voltage at the output terminals multiplied
by the output current. When using remote sense and
trim, the output voltage of the module can be
increased, which at the same output current would
increase the power output of the module. Care should
be taken to ensure that the maximum output power of
the module remains at or below the maximum rated
power.
VI (+)
VO (+)
ON/OFF SENSE(+)
CASE
VI (–)
TRIM
SENSE(–)
Radj-down
RLOAD
VO(–)
8-748 (C).c
Figure 13. Circuit Configuration to Decrease
Output Voltage
The following equation determines the required exter-
nal-resistor value to obtain a percentage output voltage
change of ý%.
Radj-down
=


1-_{∆---0-%--0--}
–
2_
kΩ
The test results for this configuration are displayed in
Figure 14. This figure applies to all output voltages.
1M
100k
SENSE(+)
SENSE(–)
SUPPLY _II
CONTACT
RESISTANCE
VI(+)
VI(–)
VO(+)
VO(–)
IO
LOAD
CONTACT AND
DISTRIBUTION LOSSES
8-651 (C).h
Figure 12. Effective Circuit Configuration for
Single-Module Remote-Sense Operation
Output Voltage Set-Point Adjustment
(Trim)
Output voltage trim (VOTRIM pin) enables the user to
increase or decrease the output voltage set point of a
module. This is accomplished by connecting an exter-
nal resistor between the VOTRIM pin and either the
SENSE(+) or SENSE(–) pins. The trim resistor should
be positioned close to the module.
If not using the trim feature, leave the VOTRIM pin
open.
With an external resistor between the VOTRIM and
SENSE(–) pins (Radj-down), the output voltage set point
(VO, adj) decreases (see
Figure 13).
10
10k
1k
100
0
10
20
30
40
% CHANGE IN OUTPUT VOLTAGE (∆%)
8-879 (C)
Figure 14. Resistor Selection for Decreased
Output Voltage
With an external resistor connected between the
VOTRIM and SENSE(+) pins (Radj-up), the output volt-
age set point (VO, adj) increases (see Figure 15).
Although the output voltage can be increased by both
the remote sense and by the trim, the maximum
increase for the output voltage is not the sum of both.
The maximum increase is the larger of either the
remote sense or the trim. Consult the factory if you
need to increase the output voltage more than the
above limitation.
Tyco Electronics Corp.