AK45C Datasheet, PDF (11/17 Pages) Astec America, Inc – 36 Vdc to 75 Vdc Inputs, 100 W

Technical Reference Notes (TRN)
Feature Descriptions
AK45C 100W Series
36 Vdc to 75 Vdc Inputs, 100 W
Output Overvoltage Clamp
The output overvoltage clamp consists of a separate control loop, independent of the primary
control loop. This control loop has a higher voltage setpoint than the primary loop. In a fault
condition the converter goes into “Hiccup Mode”, and the output overvoltage clamp ensures that
the output voltage does not exceed Vo,clamp,max. This secondary control loop provides a
redundant voltage-control that reduces the risk of output overvoltage.
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 (Optional)
Two enable option are available. Positive Logic Enable, no suffix, and Negative Logic Enable,
suffix “N”. 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 Vadj
Pin and either the +Vout or –Vout Pins.
With an external resistor between the Vadj Pin and -Sense Pin (Radj-down) the output voltage set
point (Vo,adj) decreases (see Figure 12). The following equation determines the required external
resistor value to obtain an adjusted output voltage:
Radj_down ⁵¹⁰ 10.2 ^.kohm
%Vo,adj
Where Radj-down is the resistance value and %Vo,adj is the percent change in the output voltage.
With an external resistor between the Vadj Pin and +Sense Pin (Radj-up) the output voltage set
point (Vo,adj) increases (see Figure 13). The following equation determines the required external
resistor value to obtain an adjusted output voltage:
Radj_up ^{5.1Vo.( 100 %Vo, adj)}
510 _{10.2 .kohm}
1.225.%Vo, adj
%Vo, adj
Where Radj-up is the resistance value and %Vo,adj is the percent change in the output voltage.
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