Data Sheet
September 23, 2011
QBVW033A0B Series Power Modules; DC-DC Converters
36-75V
dc
Input; 12V
dc
Output; 33A Output Current
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
Δ%
511
R
trim
down
�½
10 . 22
%
Feature Descriptions (continued)
Remote Sense (“9” Option Code)
Remote sense minimizes the effects of distribution losses
by regulating the voltage at the remote-sense connections
(See Figure 15). The SENSE(-) pin should be always
connected to V
O
(–).The voltage between the remote-sense
pins and the output terminals must not exceed the output
voltage sense range given in the Feature Specifications
table:
[V
O
(+) – V
O
(–)] – [SENSE(+) ]
0.5 V
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
).
V
V
desired
100
%
�½
o
,
set
V
o
,
set
Where
For example, to trim-down the output voltage of the 12V
nominal module by 20% to 9.6V, Rtrim-down is calculated
as follows:
%
�½
20
511
10 .22
R
trim
down
�½
20
R
trim
down
�½
15 . 3
k
Connecting an external resistor (R
trim-up
) between the TRIM
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
Δ%:
5.11
V
o
,
set
(100
%) 511
R
trim
up
�½
10 .22
1 .225
%
%
Figure 15. Circuit Configuration for remote sense.
V
V
o
,
set
100
%
�½
desired
V
o
,
set
Where
For example, to trim-up the output voltage of the 12V
module by 5% to 12.6V, R
trim-up
is calculated is as follows:
%
�½
5
5 . 11
12 . 0
(100
5 ) 511
R
trim
up
�½
10 . 22
1 . 225
5
5
Trim, Output Voltage Adjust (“9” Option Code)
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
(+)
QBVW033A0
TRIM
R
trim-down
V
O
(-)
R
trim-up
LOAD
R
trim
up
�½
938 .8
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
).
Figure 16. Circuit Configuration to Trim Output
Voltage.
Connecting an external resistor (R
trim-down
) between the
TRIM pin and the Vo(-) (or Sense(-)) pin decreases the
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POWER
9
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