TPL0102-EP: Can I use Digital Potentiometer with negative power supplies ?

Hi Anil,

TPL0102-EP can be used with negative supply. Dual supply operation is possible upto +/-2.75V

Can you please share schematics for negative LDO and how you intend to you use it? I can have a look at the same and suggest solutions

Regards,

AK

Thanks Akhilesh.

My ldo has -5v input and -3.3v output.

Digital pot ,  3 Resistance  terminals  are connected to -3.3, adj of ldo and ground.

TLP0102 is powered from +5v and zero.  It's i2c signals are also from 5V microcontroller.

Regards,

Anil

Hi Akhilesh, please  find below circuit that we plan to use - Ditgital pot with +5V power supply, its pot connected to -5V  LDO.

Would like to know whether using pot  this was is OK or not ?

Hi Anil,

You cannot use device in this  configuration, as VDD is 5V and VSS = 0. Terminal HA cannot accept -3.3V when VSS  = 0, max is -2.75V when VSS = -2.75V

what I can think of this is to make work is, you feed a portion of -3.3V output, say 2.5V to HA terminal by a divider which will not load your LDO and make VDD  = 2.75V and VSS  = -2.75V

Regards,

AK

Hi Akhilesh,

Please verify the below modified circuit as you suggested.

Hi,

You need to make sure that VSS is atleast equal to the voltage you are expecting at the WA node.

I would suggest operate TPL0102 in dual supply configuration with VDD = 2.5V and VSS = -2.5V. Otherwise this scheme will not work.

Regards,

AK

Hi Akhilesh,

Generating another +/-2.5V power supply for digital pot  is not preferred . Is TI having any digital pot that can work in this configuration ?

Regards,

Anil

Hi Anil,

We don't have any other option as of now.

Regards,

AK