GE Industrial Solutions QRW025 Series User Manual
Page 20
Lineage Power
20
Data Sheet
August 23, 2010
36 Vdc - 75 Vdc Input, 1.2 to 3.3 Vdc Output; 25A
QRW025 Series Power Modules; dc-dc Converters
Feature Descriptions
Overcurrent Protection
To provide protection in a fault output overload condition, the
module is equipped with internal current-limiting circuitry and
can endure current limit for few seconds. If overcurrent per-
sists for few seconds, the module will shut down and remain
latch-off.
The overcurrent latch is reset by either cycling the input
power or by toggling the on/off pin for one second. If the out-
put overload condition still exists when the module restarts, it
will shut down again. This operation will continue indefinitely
until the overcurrent condition is corrected.
An auto-restart option is also available.
Remote On/Off
Two remote on/off options are available. Positive logic
remote on/off turns the module on during a logic-high volt-
age on the ON/OFF pin, and off during a logic low. Negative
logic remote on/off turns the module off during a logic high
and on during a logic low. Negative logic, device code suffix
"1," is the factory-preferred configuration.
To turn the power module on and off, the user must supply a
switch to control the voltage between the on/off terminal and
the VI(-) terminal (Von/off). The switch can be an open col-
lector or equivalent (see Figure 10). A logic low is Von/off = 0
V to I.2 V. The maximum Ion/off during a logic low is 1 mA.
The switch should maintain a logic-low voltage while sinking
1 mA.
During a logic high, the maximum Von/off generated by the
power module is 15 V. The maximum allowable leakage cur-
rent of the switch at Von/off = 15V is 50 µA.
If not using the remote on/off feature, do one of the following
to turn the unit on
For negative logic, short ON/OFF pin to VI(-).
For positive logic: leave ON/OFF pin open.
Figure 34. Remote On/Off Implementation.
Remote Sense
Remote sense minimizes the effects of distribution losses by
regulating the voltage at the remote-sense connections. The
voltage between the remote-sense pins and the output ter-
minals must not exceed the output voltage sense range
given in the Feature Specifications table i.e.:
[Vo(+) – Vo(-)] – [SENSE(+) – SENSE(-)] £ 10% of Vo, rated
The voltage between the Vo(+) and Vo(-) 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 com-
pensation and output voltage set-point adjustment (trim).
See Figure 35.
If not using the remote-sense feature to regulate the output
at the point of load, then connect SENSE(+) to Vo(+) and
SENSE(-) to Vo(-) at the module.
Although the output voltage can be increased by both the
remote sense and by tine 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 volt-
age of the module can be increased, which at the same out-
put 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.
Figure 35. Effective Circuit Configuration for
Single-Module Remote-Sense Operation
Output Voltage.
Output Overvoltage Protection
The output overvoltage protection consists of circuitry that
monitors the voltage on the output terminals. If the voltage
on the output terminals exceeds the over voltage protection
threshold, then the module will shutdown and latch off. The
overvoltage latch is reset by either cycling the input power
for one second or by toggling the on/off signal for one sec-
ond.
The protection mechanism is such that the unit can continue
in this condition until the fault is cleared.
Overtemperature Protection
These modules feature an overtemperature protection circuit
to safeguard against thermal damage. The circuit shuts
down and latches off the module when the maximum device
reference temperature is exceeded. The module can be
restarted by cycling the dc input power for at least one sec-
ond or by toggling the remote on/off signal for at least one
second.
SENSE(+)
V
O
(+)
SENSE(–)
V
O
(–)
V
I
(–)
+
–
I
on/off
ON/OFF
V
I
(+)
LOAD
V
on/off
SENSE(+)
SENSE(–)
V
I
(+)
V
I
(–)
I
O
LOAD
CONTACT AND
SUPPLY
I
I
CONTACT
V
O
(+)
V
O
(–)
DISTRIBUTION LOSSES
RESISTANCE