1010 Tyco Electronics Corp.
Data Sheet
August 2001
18 Vdc to 36 Vdc and 36 Vdc to 75 Vdc Inputs, 10 W
SMC/SMW Dual-Output Series Surface-Mount Power Modules:
Feature Descriptions (continued)
Output Voltage Adjustment (continued)
With an external resistor connected between the TRIM
and VO(–) pins (Radj-up), the output voltage set point
(VO, adj) increases (see Figure 12). The following equa-
tion determines the required external resistor value to
obtain an output voltage from VO, nom to VO, adj:
where Radj-up is the resistance value connected
between TRIM and VO(–), and the values of G, H, K,
and L are shown in the following table.
Although the AJ output can be trimmed up, with mis-
matched loads, the output voltage on the lightly loaded
output will increase. The output voltage between the
COM pin and both the VO1(+) and VO2(–) pins must be
kept lower than the minimum overvoltage protection
voltage found in the Feature Specifications table. The
BK and CL modules can only be trimmed down.
8-715k
Figure 12. Circuit Configur ation to Increa se Output
Voltage
The SMC/SMW-Series Surface-Mount Power Modules
have a fixed current-limit set point. Therefore, as the
output voltage is adjusted down, the available output
power is reduced. In addition, the minimum output cur-
rent is a function of the output voltage. As the output
v oltage is adjusted down, the minimum required output
current can increase (i.e., minimum power is constant).
As the output voltage is adjusted up, the output power
should be held constant (max imum loa d curr ent
decreases).
Output Overvoltage Protection
The output overvoltage clamp consists of control cir-
cuitry, independent of the primary regulation loop, that
monitors the voltage on the output terminals. This con-
trol loop has a higher voltage set point than the primary
loop (see Feature Specifications table). In a fault condi-
tion, the overvoltage clamp ensures that the output
voltage does not exceed VO, clamp, max. This provides a
redundant voltage-control that reduces the risk of out-
put overvoltage.
Input Voltage Turn-On Adjustment
(Optional)
The input voltage at which the unit turns on can be
adjusted upward to add additional hysteresis between
the points at which the modules turn on and turn off.
This f eature can be useful when the power system has
high impedance between the source voltage and the
power unit causing the input to drop as the supply is
turned on. Please consult the factory for application
guidelines and/or a description of how to use this fea-
ture.
Synchronization (Optional)
With external circuitry, the unit is capable of synchroni-
zation from an independent time base with a switching
rate of 256 kHz. Other frequencies may be available;
please consult the factory for application guidelines
and/or a description of the external circuit needed to
use this feature.
Thermal Considerations
The power module operates 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, and radiation to the surrounding
environment. Proper cooling can be verified by mea-
suring the case temperature. The case temperature
(TC) should be measured at th e position indicated in
Figure 13.
GHKL
SMx010AJ 10000 2050 7.5 2.49
SMx010BK 45300 2050 —2.49
SMx010CL 45300 2050 —2.49
Radj-up GL
VO adj,L
–()
K
–[]
-----------------------------------------H
–
Ω=
VI(+)
VI(-)
VO1(+)
VO2(-)
TRIM
Radj-up
RLOAD1
COM RLOAD2