GE Industrial Solutions EBDW025A0B Barracuda Series - Manual (Page 11)

GE
Data Sheet
EBDW025A0B Barracuda™ Series; DC-DC Converter Power Modules
36-75Vdc Input; 12.0Vdc, 25.0A, 300W Output
April 15, 2013 ©2012 General Electric Company. All rights reserved. Page 11
Feature Descriptions (continued)
Power Good, PG
The EBDW025A0B module provides a Power Good (PG) feature,
which compares the module’s output voltage to the module’s
POWER_GOOD_ON and POWER_GOOD_OFF values. These
values are adjustable via PMBus. PG is asserted when the
module’s output voltage is above the POWER_GOOD_ON
value, and PG is de-asserted if any condition such as
overtemperature, overcurrent or loss of regulation occurs that
would result in the output voltage going below the
POWER_GOOD_OFF value.
The PG signal, provided on pin C2, is implemented with an
open-drain node, pulled up via a 10kΩ resistor to 3.3V
internally. For Positive Logic PG (default), the PG signal is HI,
when PG is asserted, and LO, when the PG is de-asserted. For
Negative Logic PG, the PG signal is LO, when PG is asserted,
and HI, when the PG is de-asserted.
The PMBus command MFR_PGOOD_POLARITY is used to set
the logic polarity of the signal.
If not using the Power Good feature, the pin may be left N/C.
Trim, Output Voltage Programming
Trimming allows the output voltage set point to be increased
or decreased; this is accomplished by connecting an external
resistor between the TRIM pin and either the V
O
(+) pin or the
V
O
(-) pin.
V
O
(+)
T/C1
V
O
(-)
R
trim-down
LOAD
EBDW025A0B
R
trim-up
Figure 17. Circuit Configuration to Trim Output Voltage.
Connecting an external resistor (R
trim-down
) between the T/C1
pin and the Vo(-) (or Sense(-)) pin decreases the output voltage
set point. To maintain set point accuracy, the trim resistor
tolerance should be ±1.0%.
The following equation determines the required external
resistor value to obtain a percentage output voltage change of
∆%.








 22 . 10
%
511
down trim
R
Where
100
0 . 12
0 . 12
%
 




 
 
V
V V
desired
For example, to trim-down the output voltage of the module
by 20% to 9.6V, Rtrim-down is calculated as follows:
20 %
 





 

22 . 10
20
511
down trim
R
 

k R
down trim
3 . 15
Connecting an external resistor (R
trim-up
) between the T/C1 pin
and the V
O
(+) (or Sense (+)) pin increases the output voltage set
point. The following equations determine the required external
resistor value to obtain a percentage output voltage change of
∆%:








 
   


22 . 10
%
511
% 225 . 1
%) 100 ( 0 . 12 11 . 5 V
R
up trim
Where
100
0 . 12
0 . 12
%
 




 
 
V
V V
desired
For example, to trim-up the output voltage of the module by
5% to 12.6V, R
trim-up
is calculated is as follows:
5 %
 





 

  


22 . 10
5
511
5 225 . 1
) 5 100 ( 0 . 12 11 . 5
up trim
R
 

8 . 938
up trim
R
The voltage between the Vo(+) and Vo(–) terminals must not
exceed the minimum output overvoltage protection value
shown in the Feature Specifications table. This limit includes
any increase in voltage due to remote-sense compensation
and output voltage set-point adjustment trim.
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. 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
(Maximum rated power = V
O,set
x I
O,max
).
Thermal Considerations
The power modules operate in a variety of thermal
environments and sufficient cooling should be provided to help
ensure reliable operation.
Thermal 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 presented here is based on physical
measurements taken in a wind tunnel, using automated
thermo-couple instrumentation to monitor key component
temperatures: FETs, diodes, control ICs, magnetic cores,
ceramic capacitors, opto-isolators, and module pwb
conductors, while controlling the ambient airflow rate and
temperature. For a given airflow and ambient temperature, the
module output power is increased, until one (or more) of the
components reaches its maximum derated operating