JAHW050F, JAHW075F, and JAHW100F Power Modules:
dc-dc Converters; 36 to 75 Vdc Input, 3.3 Output; 33 W to 66 W
Data Sheet
August 2000
Feature Descriptions
Overcurrent Protection
To provide protection in an output overload condition,
the unit is provided with internal shutdown and auto-
restart mechanism.
At the instance of current-limit inception, the module
enters a "hiccup" mode of operation whereby it shuts
down and automatically attempts to restart. As long as
the fault persists, the module remains in this mode.
The protection mechanism is such that the unit can
continue in this condition for a sufficient interval of time
until the fault is cleared.
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 out-
put voltage sense range given in the Feature Specifica-
tions table, i.e.:
[V
O
(+) – V
O
(–)] – [SENSE(+) – SENSE(–)]
≤
0.5 V
The voltage between the V
O
(+) and V
O
(–) 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 20.
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.
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. Consult the factory if you
need to increase the output voltage more than the
above limitation.
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.
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 dur-
ing 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 V
I
(–) terminal (V
on/off
). The
switch can be an open collector or equivalent (see
Figure 19). A logic low is V
on/off
= 0 V to 1.2 V. The
maximum I
on/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 V
on/off
generated by
the power module is 15 V. The maximum allowable
leakage current of the switch at V
on/off
= 15 V is 50 µA.
If not using the remote on/off feature, do one of the
following to turn the unit on:
s
s
SENSE(+)
SENSE(–)
V
I
(+)
SUPPLY
I
I
V
I
(–)
V
O
(–)
CONTACT AND
DISTRIBUTION LOSSES
8-651 (F).m
For negative logic, short ON/OFF pin to V
I
(–).
For positive logic, leave ON/OFF pin open.
I
on/off
+
V
on/off
–
ON/OFF
SENSE(+)
V
O
(+)
LOAD
V
I
(+)
V
I
(–)
V
O
(–)
SENSE(–)
CONTACT
RESISTANCE
V
O
(+)
I
O
LOAD
Figure 20. Effective Circuit Configuration for
Single-Module Remote-Sense Operation
8-720 (F).c
Figure 19. Remote On/Off Implementation
10
Lucent Technologies Inc.
ETC [ ETC ]
