AD5422 - Connecting multiple DVCC outputs together

Document created by lallison Employee on Apr 3, 2017Last modified by lallison Employee on Sep 6, 2017
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I want to use multiple AD5422 IC's, all with DVCC SELECT pin unconnected (use of internal LDO).

Is it possible to connect all DVCC outputs together to get more current for external circuitry?
Or do I have to use diodes to decouple DVCC output?

 

Regards

 

Hi della,

 

Connecting multiple LDO to produce a higher current is a bit tricky especially if you have a low current limit (short circuit current in case of the AD5422 is only 20mA typical). You have to make sure that output of each LDO is at the same level so that they would share the total current equally. Although the DVCC output of the AD5422 is regulated, it is still possible to have some error between multiple parts and this would cause the load to draw more current from the higher output LDO. That LDO might enter current limit and will cause the parallel output to drop to <2V and even if you connect diodes, this will still be the case if the LDO outputs are mismatched.

 

You also have to remember that the LDO is also shared with the internal digital blocks of the DAC which makes the output current to only about 15mA or even less.

 

Best regards,

Rainier

 

Dear Rainier,

 

thank you for the information.

So I think it will be better to deal with only one DVCC output to supply external circuitry.

And also meet the DVCC output load current of 5mA given in the AD5422 datasheet.

 

Thanks

 

This document was generated from the following discussion: AD5422 - Connecting multiple DVCC outputs together

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