DS_Q48SP12017_05302008
8
FEATURES DESCRIPTIONS
Over-Current Protection
The modules include an internal output over-current
protection circuit, which will endure current limiting for
an unlimited duration during output overload. If the
output current exceeds the OCP set point, the modules
will automatically shut down and latch off.
Over-Voltage Protection
The modules include an internal output over-voltage
protection circuit, which monitors the voltage on the
output terminals. If this voltage exceeds the over-
voltage set point, the module will shut down and latch
off. Cycling the input power for one second can reset
the over-voltage latch.
Over-Temperature Protection
The over-temperature protection consists of circuitry
that provides protection from thermal damage. If the
temperature exceeds the over-temperature threshold
the module will shut down.
The module will try to restart after shutdown. If the over-
temperature condition still exists during restart, the
module will shut down again. This restart trial will
continue until the temperature is within specification.
Remote On/Off
The remote on/off feature on the module can be either
negative or positive logic. Negative logic turns the
module on during a logic low and off during a logic high.
Positive logic turns the modules on during a logic high
and off during a logic low.
Remote on/off can be controlled by an external switch
between the on/off terminal and the Vi(-) terminal. The
switch can be an open collector or open drain.
For negative logic if the remote on/off feature is not
used, please short the on/off pin to Vi(-). For positive
logic if the remote on/off feature is not used, please
leave the on/off pin floating.
Vo(+)
Vi(+)
Vo(-)
Sense(-)
Sense(+)
Vi(-)
ON/OFF
Figure 15:
Remote on/off implementation
Remote Sense
(Not applicable to Q48SP120017Exxx)
Remote sense compensates for voltage drops on the
output by sensing the actual output voltage at the point
of load. The voltage between the remote sense pins
and the output terminals must not exceed the output
voltage sense range given here:
[Vo(+) – Vo(–)] – [SENSE(+) – SENSE(–)]
≤
0.5V
This limit includes any increase in voltage due to
remote sense compensation and output voltage set
point adjustment (trim).
Vi(-)
Vi(+)
Vo(-)
Vo(+)
Sense(+)
Sense(-)
Resistance
Contact
Contact and Distribution
Losses
Figure 16:
Effective circuit configuration for remote sense
operation
If the remote sense feature is not used to regulate the
output at the point of load, please connect SENSE(+)
to Vo(+) and SENSE(–) to Vo(–) at the module.
The output voltage can be increased by both the
remote sense and the trim; however, the maximum
allowed increase is the larger of either the remote
sense spec or the trim spec, not the sum of both.
When using remote sense and trim, the output voltage
of the module is usually increased, which increases the
power output of the module with the same output
current.
Care should be taken to ensure that the maximum
output power does not exceed the maximum rated
power.