ramesh_cdac

Re: How to solve noise related issues in ADuM4223

Discussion created by ramesh_cdac on Dec 19, 2016
Latest reply on Dec 19, 2016 by RSchnell
Branched from an earlier discussion

Hi RSchnell,

 

How are you doing ?

 

The technical issues which i addressed earlier were solved by improving PCB layout.Moreover, i put cable ferrite  over the PWM signal-FRC connector.It helped a lot in rectifying the above noise related issues.

 

Now,i have come up with an other issue. Pls read the following.

Consider a  typical Full bridge dc-dc converter using H bridge circuit.In my application,i have connected MOSFETs in H bridge configuration in place of output diodes .The MOSFETs in INPUT H bridge are active.

There is a mode of operation where i need to disable all the MOSFETs in OUTPUT H bridge to form Full bridge rectifier using internal Antiparallel diodes.

I tried the rectifier operation by applying Zero PWM signal.But,i have noticed some unwanted PWM signal across GATE and SOURCE of MOSFET even with OFF command to the ADuM4223 input.The input source(POWER) starts drawing high current even with 1 V DC input.There seems to be a shoot through conditions between TOP & BOTTOM MOSFETs.

I am checking the waveforms which i will let you know later.Before that pls ensure which of the following method is correct to ENABLE rectifier mode of operation by DISABLING the MOSFETs in output H Bridge.

 

1, Applying PWM OFF signals to all the MOSFETs to realize rectifier operation

2, forcing DISABLE pin of IC to HIGH to ensure zero output Pulse from IC output(i.e) VoA & VoB =0

 

 

Pls provide your suggestions.

 

- Ramesh.P

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