AFL50XXS Datasheet, PDF (9/11 Pages) International Rectifier – ADVANCED ANALOG HIGH RELIABILITY HYBRID DC/DC CONVERTERS

AFL50XXS Series
General Application Information
The AFL50XXS series of converters are capable of pro-
viding 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 tran-
sients, it is recommended that the input leads be made of
adequate size to minimize resistive losses, and that a good
quality capacitor of approximately100µfd be connected di-
rectly across the input terminals to assure an adequately
low impedance at the input terminals. Table I relates nomi-
nal resistance values and selected wire sizes.
Table 1. Nominal Resistance of Cu Wire
Wire Size, AWG
24 Ga
22 Ga
20 Ga
18 Ga
16 Ga
14 Ga
12 Ga
Resistance per ft
25.7 mΩ
16.2 mΩ
10.1 mΩ
6.4 mΩ
4.0 mΩ
2.5 mΩ
1.6 mΩ
Incorporation of a 100 µfd capacitor at the input terminals
is recommended as compensation for the dynamic ef-
fects 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
(See text)
R_p
e_source
R_p
System Ground
I_in
Vin
100
I_Rtn
µfd
e_Rtn
Rtn
Case
Enable 1
Sync Out
Sync In
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