1010 Tyco Electronics Corp.
Data Sheet
March 2005
dc-dc Con verters; 36 to 75 Vdc Input, 1.8 Vdc Output; 18 W to 36 W
JAHW050Y, JAHW075Y, and JAHW100Y Power Modules:
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 pers ists, the mod ule rem a ins in this mo de.
The protecti on mechanism is such that the unit can
continue in this condition for a sufficient interval of time
until the fault is cleared.
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 VI(–) terminal (Von/off). The
switch can be an open collector or equivalent (see
Figure 20). A logic low is Von/off = 0 V to 1.2 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 = 15 V is 50 µA.
If not using the remote on/ off feature, do one of the
following to turn the unit on:
■F or negativ e logic, short ON/OFF pin to VI(–).
■For positive logic, leave ON/OFF pin open.
8-720 (F).c
Figure 20. Remote On/ Off Implementation
Remote Sense
Remote sense minimizes the effects of distribution
losses by re gulating 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 r ange gi ven in the Feature Specifica-
tions table, i.e .:
[VO(+) – VO(–)] – [SENSE(+) – SENSE(–)] ≤ 0.5 V
The voltage between the VO( +) and VO(–) terminals
must not exceed th e min i mum outp u t overvoltage shut-
down value indicated in the Feature Specifications
table. This limit includes any increase in v olt age du e to
remote-sense compensation and output voltage set-
point adjustment (trim). See Figure 21.
If not using the rem o te- se nse featur e to regulate the
output at the poin t of load, then connect SENSE(+) to
VO(+) and SENSE(–) to VO(–) at the module.
Although the out put 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 b y the module is defined
as the v oltage at the output terminals multiplied b y the
output current. When using remote sense and trim, the
output v oltage of the module can be increased, which at
the same output current would increase the po wer output
of the module. Care should be tak en to ensure that the
maximum output po wer of the module remains at or
below the maximum r ated po w er.
SENSE(+)
VO(+)
SENSE(–)
VO(–)
VI(–)
+
–
Ion/off ON/OFF
VI(+)
LOAD
Von/off