ADM1075 datasheet(27/52 Pages) AD

27 / 52 page

Data Sheet

ADM1075

Rev. A | Page 27 of 52

be powered from the secondary side and can provide power

across the isolation barrier via the integrated dc-to-dc

converter. Therefore, the ADuM5404 can be used to power the

primary side of the ADuM1250 if both are used on the board.

Some extra care is required if using the ADuM5404 to power

the ADuM3200. If the power at the secondary side is enabled by

the ADM1075, the isoPower solution may not work. Because

isoPower is unpowered in this case, the ADuM3200 outputs are

in an undefined state. If the SHDN input comes from the

, it may be held low, and the

never turns

on the FET or enables power at the secondary side.

ADuM3200

ADM1075

If a voltage rail is available on the primary side (3.3 V or 5 V

referenced to VEE), that can be used to power the chip directly.

Otherwise, the ADM1075 shunt voltage and/or the −48 V

supply can be regulated down to power the part. A simple

emitter follower circuit achieves this, as shown in Figure 54.

12V (SHUNT)

–48V RTN

–48V

5V AUX

20kΩ

1kΩ

0.33W

1µF

20k

isoPower uses high frequency switching elements to transfer

power through its transformer. Special precautions must be

taken during printed circuit board (PCB) layout to meet

emissions standards. See the AN-0971 Application Note for

board layout recommendations.

Figure 54. Powering iCoupler from −48 V Supply

Powering the

iCouplers from the secondary side is usually

straightforward because there is often a suitable voltage rail

available. However, there is not always a suitable voltage rail

available on the primary side (−48 V side). If the ADuM5404 is

not used on the system, the ADuM1250 can be powered on the

primary side in a number of different ways.

ADM1075 Datasheet(PDF) 27 Page - Analog Devices

ADM1075 Datasheet(HTML) 27 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

Datasheet Download

Link URL