Idle Vout of V+ at AD3

[plswelcomeroh]

Hi team,

Can you please check it?

Recently I placed the order and checked V+ output noise of AD3.

However, it is 120mV output offset during V- makes 19mV even though I calibrated newly.

Is it the in range spec? I believe it is NOT normal. Too much high 120mV V+ for lab equipment.

 

Thanks in advance, can you please update me?

[plswelcomeroh]

Hi team again,

As I updated about Idle offset of V+,

when I measured in close loop,

i.e., connected V+ to scope ch1 directly, and connected V- to scope ch2 directly. 

 

V+ is 192mV, during V- is only 4mV.

 

Any support for it? I bought it from Mouser Korea,

 

Do I need to contact them? Could you please let me know how do I do / change AD3 if it is bad?

 

Thanks.

 

 

[attila]

Hi @plswelcomeroh

This is expected. It is the leakage current from the voltage monitor and setting rails.
It can be minimize with a dummy load, like 1k resistor.

[plswelcomeroh]

Hi Attila,

Thank you for supporting it and sorry about that I don't think so. 

 

Can you please let me know the device full name of power rail for V+/V-? 

And if so, what is the maximum expected level for V+ idle? (during the monitoring resolution is 8mV. 192/8=24steps)

 

Thanks in advance.  

 

Edited January 10 by plswelcomeroh

[attila]

Hi @plswelcomeroh

The maximum leakage voltage when the V+ is shut down is 641mV and with 1k dummy load max is 67mV.
The supply circuit's Schottky diode reverse current further reduces this voltage, depending on temperature. On a cold device I see 500mV and after it heats up only 50mV.

 

[plswelcomeroh]

Hi Attila,

Also I could find 641mv which is too much to use for the lab test for V+.

or I have to wait until thermal drift itself.

 

Thank you though.

 

[attila]

Hi @plswelcomeroh

Use a resistor (like 1k for max 67mV) to reduce the V+ idle voltage.