TPS3808: what is the Input current at SENSE when VDD=0

dimitry chen

Expert 1145 points

Part Number: TPS3808
Other Parts Discussed in Thread: TPS3899

Tool/software:

I am lookin for a low sensne current solution. when VDD =0.

it's for RTC battery sense

Does TPS3808 can I sense can keep <25nA when VDD =0

6 months ago

0 Jesse Villanueva 6 months ago

TI__Mastermind 18870 points

Hi Dimitry,

For RTC battery sense application, I would recommend the TPS3899 instead of the TPS3808.

The TPS3899 has an Iq of 125nA in comparison to 2.4uA of the TPS3808. Also the TPS3899 utilizes a capacitor ladder for its fixed variant instead of a resistor ladder on the SENSE pin which would minimize the Isense even with VDD=0.

https://www.ti.com/product/TPS3899

Jesse

0 dimitry chen 6 months ago in reply to Jesse Villanueva

Expert 1145 points

Hi Jesse

My design is vcc connect to main power.

and I only concenr about I sense current..

TPS3899 is not in my original design.

TPS3808 is my prefer part.

please help me to check I sense when VCC=0.

0 Jesse Villanueva 6 months ago in reply to dimitry chen

TI__Mastermind 18870 points

Hi Dimitry,

Are you using the adjustable variant, TPS3808G01, or the fixed variant, TPS3808GXX, of the device?

Jesse

0 dimitry chen 5 months ago in reply to Jesse Villanueva

Expert 1145 points

We use TPS3808G01

0 Jesse Villanueva 5 months ago in reply to dimitry chen

TI__Mastermind 18870 points

Hi Dimitry,

With the TPS3808G01, Isense at VDD=0 is 0A and with VDD=VDD(min) Isense=~25nA. With this setup, the main concern is the external resistor ladder when VDD of TPS3808 is at zero.

Jesse

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TPS3808: what is the Input current at SENSE when VDD=0