GE Industrial Solutions EHHD020A0F Hammerhead Series - Manual (Page 7)

GE Data Sheet
EHHD020A0F Hammerhead™ Series; DC-DC Converter Power Modules
18-75Vdc Input; 3.3Vdc, 20.0A, 66W Output
April 4, 2013 ©2012 General Electric Company. All rights reserved. Page 7
Feature Descriptions
Remote On/Off
Two remote on/off options are available. Positive logic 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,
device code suffix “1”, turns the module off during a logic
high and on during a logic low.
ON/OFF
Vin+
Vin-
I on/off
V
on/off
Vout+
TRIM
Vout-
Figure 10. Remote On/Off Implementation.
To turn the power module on and off, the user must supply a
switch (open collector or equivalent) to control the voltage
(V
on/off
) between the ON/OFF terminal and the V
IN
(-) terminal
(see Figure 10). Logic low is 0V ≤ V
on/off
≤ 0.6V. The maximum
I
on/off
during a logic low is 0.15mA; the switch should
maintain a logic low level whilst sinking this current.
During a logic high, the typical maximum V
on/off
generated
by the module is 6.7V, and the maximum allowable leakage
current at V
on/off
= 2.5V is 25μA.
If not using the remote on/off feature:
For positive logic, leave the ON/OFF pin open.
For negative logic, short the ON/OFF pin to V
IN
(-).
Remote Sense
Remote sense minimizes the effects of distribution losses by
regulating the voltage at the remote-sense connections (See
Figure 11). 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:
[V
O
(+) – V
O
(–)] – [SENSE(+) – SENSE(–)]  0.5 V
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 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 (Maximum rated power = Vo,set x
Io,max).
Figure 11. Circuit Configuration for remote sense.
Input Undervoltage Lockout
At input voltages below the input undervoltage lockout limit,
the module operation is disabled. The module will only
begin to operate once the input voltage is raised above the
undervoltage lockout turn-on threshold, V
UV/ON
.
Once operating, the module will continue to operate until
the input voltage is taken below the undervoltage turn-off
threshold, V
UV/OFF
.
Overtemperature Protection
To provide protection under certain fault conditions, the unit
is equipped with a thermal shutdown circuit. The unit will
shutdown if the thermal reference point, Tref, exceeds 135
o C
(Figure 13, typical) or 120 o C (Figure 14, typical), but the
thermal shutdown is not intended as a guarantee that the
unit will survive temperatures beyond its rating. The module
will automatically restart upon cool-down to a safe
temperature.
Output Overvoltage Protection
The output over voltage protection scheme of the modules
has an independent over voltage loop to prevent single
point of failure. This protection feature latches in the event
of over voltage across the output. Cycling the on/off pin or
input voltage resets the latching protection feature. If the
auto-restart option (4) is ordered, the module will
automatically restart upon an internally programmed time
elapsing.
Overcurrent Protection
To provide protection in a fault (output overload) condition,
the unit is equipped with internal
current-limiting circuitry and can endure current
limiting continuously. At the point of current-limit
inception, the unit enters hiccup mode. If the unit is
not configured with auto–restart, then it will latch off
following the over current condition. The module can be
restarted by cycling the dc input power for at least one
second or by toggling the remote on/off signal for at least
one second.
V O (+)
SENSE(+)
SENSE(–)
V O (–)
V I (+)
V I (-)
I O LOAD
CONTACT AND
DISTRIBUTION LOSSE
SUPPLY
I I
CONTACT
RESISTANCE