TS5A3159 Analog Switch Issue

Rich Soennichsen

Other Parts Discussed in Thread: TS5A3159

Hi,

I am attempting to design the TS5A3159 into a product, as a replacement for two mechanical switches. I am having some problems and I think it is related to the the switch common (pin 4) going 0.5V below our digital ground, which is used as a ground for the device (pin 2). Our product is a loop powered (4-20 mA) and so there is ground and there is ground... Have you seen this issue and do you have any suggestions about a workaround?

Thank you

Rich

over 10 years ago

0 Adam Torma over 10 years ago

TI__Mastermind 45585 points

Rich,

Thank you for your post. Could you provide us with a schematic and scope shots of your system? Please add a little more clarity on what you mean by "so there is ground and there is ground..."? The more information you can provide about the problem will help expedite the debug process.

I have notified the appropriate applications engineer for support.

Thank you,

Adam

0 ShreyasRao over 10 years ago

TI__Guru 62320 points

Hi Rich ,

COM pin going -0.5V below your ground will forward bias your ESD protection diode internal to the device and you will be violating the max spec condition of the device .The device tends to get damaged if you have it that way for extended periods of time .

You can see the abs max voltage range conditions in the datasheet of the device . I would not suggest to have COM pin or any other pin go below 0V in the your application .Try to have an offset to the signal if possible .

0 Rich Soennichsen over 10 years ago in reply to ShreyasRao

Prodigy 200 points

Yes,
I believe that is what I am seeing. I I have a possible solution that puts the device ground pin at or below the negative voltage on the switch. The control pin is then handled by a bjt that brings it to the same level as the gnd pin for logic 0 when off and to Vcc when on.

Rich

0 Rich Soennichsen over 10 years ago in reply to ShreyasRao

Prodigy 200 points

Hi again,
Is this switch in a defined state when un-powered? In other words if it is being used upstream of it's own Vcc supply regulator....

Thank you

Rich