
Datasheet
HWD Series – 75 Watt, Half-Brick DC/DC Converter
Wide Input Range
Dual Output
REV. 9/01 Page 8 of
15
www.power-one.com
Output Current Protection
To provide protection in an output overload or short circuit condition, the converter is equipped with current
limiting circuitry and can endure the fault condition for an unlimited duration. At the point of current-limit
inception, the converter goes into “Hiccup Mode”, causing the output current to be limited both in peak and
duration. The converter operates normally once the output current is brought back into its specified range.
Enable
Two enable options are available. Positive Logic Enable and Negative Logic Enable. Positive Logic Enable turns
the converter on during a logic-high voltage on the enable pin, and off during a logic-low. Negative Logic Enable
turns the converter of during a logic-high and on during a logic-low.
Output Voltage Adjustment
Output voltage adjustment is accomplished by connecting an external resistor between the Trim Pin and either
the +Vo1 or –Vo1 Pins.
With an external resistor between the Trim Pin and +Vo1 Pin (R
adj-down
) the output voltage set point (Vo,adj)
decreases. The following equation determines the required external resistor value to obtain an adjusted output
voltage:
Radj dn
Vo adj
Vo nom
D
Vo
(
) A
adj
,
B
ohm
Where R
adj-down
is the resistance value and A, B, and D are defined in Table 7.
With an external resistor between the Trim Pin and –Vo1 Pin (R
adj-up
) the output voltage set point (Vo,adj)
increases. The following equation determines the required external resistor value to obtain an adjusted output
voltage:
Raj up
A D
Vo adj
D
(
)
C
B
ohm
Where R
adj-up
is the resistance value and A, B, C, and D are defined in Table 7:
Table 8 Output Adjustment Variables.
Output
Vo1
Vo2
A
B
C
2.5
0.8
D
2.5
2.5
4990
4990
2000
2000