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ADG1414 - Unpowered behaviour

Question asked by ada on Oct 9, 2015
Latest reply on Oct 12, 2015 by ada

Hi all,

 

I am using an ADG1414 in single supply 12V mode to control LEDs on an isolated 5V supply (routed through the Drain-Source of the switches).

 

I observe that when the ADG1414 is unpowered (all power lines floating), then the switches are not fully open and current flows through the 5V LED circuit (approx 10mA per switch).

 

There is no details in the ADG1414 datasheet on behaviour when the 12V supply is removed. We expected that the switches would be in the fully open state in this case.

 

It appears that the ADG1414 is being powered through the 5V on the Source terminals, flowing back onto the 12V rail, enough to keep the switches in a semi-closed state (The current drawn actually depends on the last on/off state of the switches).

 

Can somebody provide details of expected behaviour if power is applied to one of the Drain/Source terminals when the ADG1414 is not powered on the 12V terminals.

 

Is there an external voltage/current combination to prevent this from happening?

 

Thanks.

 

A.

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