QPW050/060A Series Power Modules; dc-dc Converters
36
75 Vdc In
ut; 1.2Vdc to 3.3Vdc Out
ut
Data Sheet
Se
t 16, 2003
12 Tyco Electronics Power Systems
meeting the requirements for safety extra-low voltage
(SELV), all of the following must be true:
The input source is to be provided with reinforced
insulation from any other hazardous voltages,
including the ac mains.
One VIN pin and one VOUT pin are to be grounded, or
both the input and output pins are to be kept
floating.
The input pins of the module are not operator
accessible.
Another SELV reliability test is conducted on the
whole system (combination of supply source and
subject module), as required by the safety agencies,
to verify that under a single fault, hazardous
voltages do not appear at the module’s output.
Note: Do not ground either of the input pins of the
module without grounding one of the output pins.
This may allow a non-SELV voltage to appear
between the output pins and ground.
The power module has extra-low voltage (ELV) outputs
when all inputs are ELV.
For input voltages exceeding –60 Vdc but less than or
equal to –75 Vdc, these converters have been evaluated
to the applicable requirements of BASIC INSULATION
between secondary DC MAINS DISTRIBUTION input
(classified as TNV-2 in Europe) and unearthed SELV
outputs (-B option only).
The input to these units is to be provided with a
maximum 15A fast-acting (or time-delay) fuse in the
unearthed lead.
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 persists 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 output 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 voltage 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 collector or equivalent (see
Figure 34). 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 current of the
switch at Von/off = 15V is 50 µA. If not using the
remote on/off feature, perform 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 terminals must not exceed the output
voltage sense range given in the Feature Specifications
table i.e.:
[Vo(+) – Vo(-)] – [SENSE(+) – SENSE(-)] ≤ 10% of Vo,nom.
The voltage between the Vo(+) and Vo(-) terminals must
not exceed the minimum output overvoltage shut-down
value indicated in the Feature Specifications table. This
limit includes any increase in voltage due to remote-
sense compensation 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 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