1212 Tyco Electronics Power Systems
Data Sheet
June 28, 2004
36 Vdc to 75 Vdc Input; 25 W
DW025 Triple Output-Series Power Modules:
Feature Descriptions
Output Overvoltage Clamp
The output overvoltage clamp consists of control cir-
cuitry, independent of the primary regulation loop, that
monitors the voltage on the output terminals. The con-
trol loop of the clamp has a higher voltage set point
than the primary loop (see Feature Specifications
tabl e). This provides a redundant voltage control that
reduces the risk of output overvoltage.
Current Limit
To provide protection in a fault (output overload) condi-
tion, the unit is equipped with internal current-limiting
circuitry. At the point of current-limit inception, the unit
shifts from voltage control to current control. If the out-
put voltage is pulled very low during a severe fault, the
current-limit circuit can exhibit either foldbac k or
tailout characteristics (output current decrease or
increase). The unit operates normally once the output
current is brought back into its specified range.
Output Voltage Set-Point Adjustment
The output voltage adjustment feature provides the
capability of increasing or decreasing the output volt-
age set point of a module. When the output voltage
adjustment f eature is used, the output voltage set point
of all three output s is adju ste d.
The output v oltage adjustmen t can be accomplished b y
using an external resistor connected between the TRIM
pin and either the VO1(+) or common pin s. With an
external resistor between the TRIM and common pins
(Radj-up), the output voltage set point (VO, adj) increases.
Note: The output voltage adjustment range must not
exceed 110% of the nominal output voltage
between the VO1(+) and common terminals.
With an external resistor conne cte d be t w ee n the TRIM
and VO1(+) pins (Radj-down), t he output voltage set point
(VO, adj) decrease s.
Note: The output voltage adjustment must be 90% or
more of the nomina l output voltage between the
VO1(+) and common terminals.
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 REMOTE ON/OFF pin, and off during a
logic low. Negative logic remote on/off, suffix code “1,”
turns the module off during a logic hi gh and on during a
logic low.
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 21). A logic low is V on/off = 0 V to 1.2 V. The max-
imum 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 10 V. The maximum allowable
leakage current of the switch at Von/off = 10 V is 50 µA.
8-758(C).a
Figure 21. Remote On/Off Implementation
Radj-up 42.35
VO, adj VO, nom–
----------------------------------
kΩ=
Radj-down VO, adj 2.5–()16.94×
VO, nom VO, adj–
-------------------------------------------------
kΩ=
+
Ion/off
-
Von/off
REMOTE
ON/OFF
VI(+)
VI( -)