GE Industrial Solutions QPW025A0F41_H - Manual (Page 8)

Data Sheet
October 5, 2009
QPW025A0F41/QPW025A0F41-H DC-DC Power Module
36-75Vdc Input; 3.3Vdc Output Voltage; 25A Output Current
LINEAGE POWER 8
Feature Descriptions (continued)
operates normally once the output current is reduced
back into its specified range.
Input Undervoltage Lockout
At input voltages below the input undervoltage lockout
limit, the module operation is disabled. The module will
begin to operate at an input voltage between the
undervoltage lockout limit and the minimum operating
input voltage.
Overtemperature Protection
T o provide over temperature protection in a fault
condition, the unit relies upon the thermal protection
feature of the controller IC. The unit will shut down if the
thermal reference point T
ref
, exceeds the specified
maximum temperature threshold, but the thermal
shutdown is not intended as a guarantee that the unit
will survive temperatures beyond its rating. The module
will automatically restart after it cools down.
Over Voltage Protection
The output overvoltage protection clamp consists of
control circuitry, independent of the primary regulation
loop, which monitors the voltage on the output
terminals. This control loop has a higher voltage set
point than the primary loop (See the overvoltage clamp
values in the Feature Specifications). In a fault
condition, the overvoltage clamp ensures that the output
voltage does not exceed V
o, clamp(max)
. This provides a
redundant voltage-control that reduces the risk of output
overvoltage.
Remote sense
Remote sense minimizes the effects of distribution
losses by regulating the voltage at the remote-sense
connections (See Figure 11). 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(+) – SENSE(–)] ≤ 10% of
V
O
,
rated
The voltage between the V
O
(+) and V
O
(– ) terminals must
not exceed the minimum output overvoltage shutdown
value indicated in the Feature Specifications table. This
limit includes any increase in voltage due to remote-
sense compensation and output voltage setpoint
adjustment (trim) (see Figure 11). If not using the
remote-sense feature to regulate the output at the point
of load, then connect SENSE(+) to V
O
(+) and SENSE( – )
to V
O
( – ) at the module.
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 O (+)
SENSE(+)
SENSE(–)
V O (–)
V I (+)
V I (-)
I O LOAD
CONTACT AND
DISTRIBUTION LOSSE
SUPPLY
I I
CONTACT
RESISTANCE
Figure 11. Circuit Configuration to program output
voltage using external resistor.
Output Voltage Programming
Trimming allows the user to increase or decrease the
output voltage set point of a module. This is
accomplished by connecting an external resistor
between the TRIM pin and either the SENSE(+) or
SENSE(-) pins. 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 12 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
.
V
O
(+)
TRIM
V
O
(-)
R
trim-down
LOAD
V
IN
(+)
ON/OFF
V
IN
(-)
R
trim-up
SENSE (+)
SENSE (-)
Figure 12. Circuit Configuration to program output
voltage using an external resistor.
The following equations determine the required external
resistor value to obtain a percentage output voltage
change of Δ%.
To decrease output voltage set point:
Ω ⎟
⎠
⎞
⎜
⎝
⎛
−
Δ
=
− K R
down trim
2 . 10
%
510