AIF25R48 Series Technical Reference Note

DATE: May 28, 2003

MODEL : AIF25R48 SERIES

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Design Consideration

Typical Application

LOAD

+VIN

-VIN

CNT1

+VOUT

-VOUT

+SENSE

-SENSE

TRM

F1

Cin

Vin

Co1

Co2

S1

Fig.10 typical application

F1: 30A

Cin: Recommended 470 F/100V low ESR Aluminum capacitor.

Co1: Recommended 1 F/50V film capacitor.

Co2: Recommended 1000 F/50V low ESR Aluminum capacitor.

Fusing

The AIF25R48 series power modules have no internal fuse. An external fuse must always be

employed! To meet international safety requirements, a 250 Volt rated fuse should be used.

If one of the input lines is connected to chassis ground, then the fuse must be placed in the

other input line.

Standard safety agency regulations require input fusing. Recommended fuse ratings for the

AIF25R48 series are 30A.

Input Reverse Voltage Protection

Under installation and cabling conditions where reverse polarity across the input may occur,

reverse polarity protection is recommended. Protection can easily be provided as shown in

Figure ‘Reverse Polarity Protection Circuit’. In both cases the diode used is rated for

40A/100V. Placing the diode across the inputs rather than in-line with the input offers an

advantage in that the diode only conducts in a reverse polarity condition, which increases

circuit efficiency and thermal performance.