Data Sheet
June 29, 2009
Feature Descriptions
(continued)
EHW007A0B Series Eighth-Brick Power Modules
36–75Vdc Input; 12.0Vdc Output; 7A Output Current
⎡
5.11
×
V
o
,
set
×
(100
+ Δ
%) 511
⎤
R
trim
−
up
= ⎢
−
−
10 .22
⎥ ΚΩ
1.225
× Δ
%
Δ
%
⎣
⎦
Where
⎛
V
−
V
o
,
set
Δ
%
= ⎜
desired
⎜
V
o
,
set
⎝
⎞
⎟ ×
100
⎟
⎠
one second or by toggling the remote on/off signal for
at least one second. If the unit is configured with the
auto-restart option (4), it will remain in the hiccup
mode as long as the overcurrent condition exists; it
operates normally, once the output current is brought
back into its specified range. The average output
current during hiccup is 10% I
O, max
.
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.
For example, to trim-up the output voltage of the
module by 5% to 12.6V, R
trim-up
is calculated is as
follows:
Δ
%
=
5
⎡
5 . 11
×
12 . 0
×
(100
+
5 ) 511
⎤
R
trim
−
up
= ⎢
−
−
10 . 22
⎥ ΚΩ
1 . 225
×
5
5
⎣
⎦
R
trim
−
up
=
938 .8
ΚΩ
The voltage between the V
O
(+) and V
O
(–) 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
).
V
IN
(+)
V
O
(+)
R
trim-up
ON/OFF
V
O
TRIM
R
trim-down
V
IN
(-)
V
O
(-)
LOAD
Figure 12. Circuit Configuration to Trim Output
Voltage.
Connecting an external resistor (R
trim-down
) between
the TRIM pin and the V
O
(-) (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
Δ%
⎡
511
⎤
−
10 . 22
⎥ ΚΩ
R
trim
−
down
= ⎢
⎣ Δ
%
⎦
Thermal Considerations
The 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 presented here is based on physical
measurements taken in a wind tunnel.
The thermal reference point, T
ref
used in the
specifications for open frame modules is shown in
Figure 13. For reliable operation this temperature
o
should not exceed 123 C.
The thermal reference point, T
ref
used in the
specifications for modules with heatplate is shown in
Figure 14. For reliable operation this temperature
o
should not exceed 110 C.
Where
Δ
%
= ⎛
V
o
,
set
−
V
desired
⎜
⎜
V
o
,
set
⎝
⎞
⎟ ×
100
⎟
⎠
For example, to trim-down the output voltage of the
module by 8% to 11.04V, Rtrim-down is calculated as
follows:
Δ
%
=
8
⎡
511
⎤
R
trim
−
down
= ⎢
−
10 .22
⎥ ΚΩ
⎣
8
⎦
R
trim
−
down
=
53 . 655
ΚΩ
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 equation
determines the required external resistor value to
obtain a percentage output voltage change of
Δ%:
LINEAGE
POWER
8
LINEAGEPOWER [ LINEAGE POWER CORPORATION ]
