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7

AHV28XX Series

Application Information

EMI Filter

Inhibit Function

Connecting the inhibit pin (Pin 2 of single and dual models,

pin 8 of triple models) to the input return (pin 10) will cause

the converter to shutdown and operate in a low power

standby mode. Power consumption in this mode is calcu-

lated by multiplying Vin times the input current inhibited,

typically 225mW at Vin equal to 28 volts. The input current

inhibited is relatively constant with changes in Vin. The open

circuit inhibit pin voltage is typically 11.5 volts and can be

conveniently driven by an open collector driver. An internal

pull-up resistor enables the user to leave this pin floating if

the inhibit function is not used in their particular application.

All models use identical inhibit internal circuits. Forcing in-

hibit pin to any voltage between 0 and 6 volts will assure the

converter is inhibited. The input current to this pin is 500

µA

maximum at Vpin2 = to 0 volts. The converter can be turned

on by opening Pin 2 or forcing a voltage from 10 to 50 volts.

Inhibit pin current from 10 to 50 volts is less than ±50

µA.

An optional EMI filter ( AFC461) will reduce the input ripple

current to levels below the limits imposed by MIL-STD-

461 CEO3.

The output voltage of the AHV28XXS can be adjusted

upward by connecting a resistor between the Output

Adjust (Pin 3) and the Output Common (Pin 4) as shown

in Table 1.

Table 1: Output Adjustment Resistor Values

* Output Adjust (Single Output Models Only)

Output Voltage Increase (%)

* Resistance (Ohms)

Pin 3 to 4

5V

12V

15V

None

0

0

0

390 K

+1.0%

+1.6%

+1.7%

145 K

+2.0%

+3.2%

+3.4%

63 K

+3.1%

+4.9%

+5.1%

22 K

+4.1%

+6.5%

+6.8%

0

+5.0%

+7.9%

+8.3%