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9

AFL50XXS Series

General Application Information

Table 1. Nominal Resistance of Cu Wire

The AFL50XXS series of converters are capable of

providing large transient currents to user loads on demand.

Because the nominal input voltage range in this series is

relatively low, the resulting input current demands will be

correspondingly large. It is important therefore, that the line

impedance be kept very low to prevent steady state and

transient input currents from degrading the supply voltage

between the voltage source and the converter input. In

applications requiring high static currents and large

transients, it is recommended that the input leads be made

of adequate size to minimize resistive losses, and that a

good quality capacitor of approximately 100

µF be connected

directly across the input terminals to assure an adequately

low impedance at the input terminals. Table I relates nominal

resistance values and selected wire sizes.

Wire Size, AWG

Resistance per ft

24 Ga

25.7 m

Ω

22 Ga

16.2 m

Ω

20 Ga

10.1 m

Ω

18 Ga

6.4 m

Ω

16 Ga

4.0 m

Ω

14 Ga

2.5 m

Ω

12 Ga

1.6 m

Ω

Incorporation of a 100µF capacitor at the input terminals is

recommended as compensation for the dynamic effects

of the parasitic resistance of the input cable reacting with

the complex impedance of the converter input, and to

provide an energy reservoir for transient input current

requirements.

Figure VI. Problems of Parasitic Resistance in input Leads

Vin

Rtn

Case

Enable 1

Sync Out

Sync In

R

p

R

p

I

Rtn

I

in

e

source

System Ground

e

Rtn

100

µfd

(See text)