Data Sheet
EQD075 Series Single Output: Eighth Brick Power Modules:
18-60Vdc Input; 3.3 to 5.0Vdc Output; 75W
March 25, 2008
shutdown an internal feature implemented in the
module ensures there will be no reverse current.
Feature Descriptions (continued)
Output Voltage Programming
Thermal Considerations
The output voltage is adjustable between 3.0 to 5.5V
(A version). A resistor placed between the Trim pin
and Sense (+) increases the output voltage and a
resistor placed between the Trim pin and Sense (-)
decreases the output voltage. Figure 22 shows the
circuit configuration using an external resistor. The
trim resistor should be positioned close to the module.
If the trim pin is not used then the pin shall be left
open. If no trim resistor is connected, for the A
version, the output voltage will be 5V.
Power modules operate in a variety of thermal
environments; however, sufficient cooling should be
provided to help ensure reliable operation.
Considerations include ambient temperature, airflow,
module power dissipation, and the need for increased
reliability. A reduction in the operating temperature of
the module will result in an increase in reliability. The
thermal data is based on physical measurements
taken in a wind tunnel. The test set-up is shown in
Figure 23.
The following equations determine the required
external resistor value to obtain a percentage output
voltage change of Δ%.
25.4_
(1.0)
Wind Tunnel
PWBs
To decrease output voltage set point:
Power Module
510
⎛
⎜
⎞
⎠
Rtrim − down
=
−10.2 KΩ
⎟
Δ%
⎝
Where,
V
o, nom −Vdesired
76.2_
(3.0)
Δ% =
×100
V
o, nom
x
Vdesired = Desired output voltage set point (V).
To increase the output voltage set point
Probe Location
for measuring
airflow and
ambient
temperature
6.55_
(0.258)
5.1*Vo, nom
*
100+ Δ%
)
510
⎛
⎜
⎞
Rtrim − up
=
−
−10.2 KΩ
⎟
1.225*Δ%
Δ%
⎝
⎠
Air
flow
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 absolute increase in output voltage,
due to simultaneous remote sense and trim
Figure 23. Thermal Test Set up.
increases, shall not exceed the larger of the specified
individual remote sense or trim maximum limits shown
in the Features Specifications table.
The thermal reference point, Tref, used in the
specifications is shown in Figure 24. For reliable
operation, this temperature should not exceed 125OC.
Please refer to the Application Note “Thermal
Characterization Process For Open-Frame Board-
Mounted Power Modules” for a detailed discussion of
thermal aspects including maximum device
temperatures.
VO(+)
VIN(+)
SENSE (+)
Rtrim-up
ON/OFF
LOAD
TRIM
Rtrim-down
SENSE (-)
VO(-)
VIN(-)
Tref
Figure 22. Circuit Configuration to program output
voltage using an external resistor.
Figure 24. Tref Temperature Measurement
Location.
Pre-Bias Immunity
The modules are able to start into a pre-biased output
with a monotonic rise of the output voltage. During
11
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