Data Sheet
October 1997
10
10
Tyco Electronics Corp.
18 Vdc to 36 Vdc Input, 12 Vdc Output; 50 W to 100 W
JC050B, JC075B, JC100B Power Modules: dc-dc Converters;
Feature Descriptions (continued)
Output Voltage Set-Point Adjustment
(Trim) (continued)
8-879 (C)
Figure 17. Resistor Selection for Decreased
Output Voltage
8-715 (C).d
Figure 18. Circuit Configuration to Increase
Output Voltage
8-880a
Figure 19. Resistor Selection for Increased Output
Voltage
Output Overvoltage Clamp
The ouput overvoltage clamp consists of control cir-
cuitry, independent of the primary regulation loop, that
monitors the voltage on the output terminals. The con-
trol loop of the clamp has a higher voltage set point
than the primary loop (see Feature specifications
table). this provides a redundant voltage control that
reduces the risk of output overvoltage.
Overtermperature Protection (Shutdown)
The 100 W module features an overtemperature pro-
tection circuit to safeguard against thermal damage.
The circuit shuts down the module when the maximum
case temperature is exceeded. The module restarts
automatically after cooling.
Thermal Considerations
Introduction
The power modules operate in a variety of thermal
environments; however, sufficient cooling should be
provided to help ensure reliable operation of the unit.
Heat-dissipating components inside the unit are ther-
mally coupled to the case. Heat is removed by conduc-
tion, convection,a nd radiation to the surrounding
environment. Proper cooling can be verified by mea-
suring the case temperature. Peak temperature (Tc)
occurs at the position indicated in Figu re20.
010
20
30
40
100
1k
100k
1M
% CHANGE IN OUTPUT VOLTAGE (
∆%)
10k
VI(+)
VI(–)
ON/OFF
CASE
VO(+)
VO(–)
SENSE(+)
TRIM
SENSE(–)
Radj-up
RLOAD
0
246
10
10M
% CHANGE IN OUTPUT VOLTAGE (∆%)
8
1M
100k
10k