TLV9001: Signal input without power supply

Shotaro Sakai

Part Number: TLV9001
Other Parts Discussed in Thread: OPA2206, OPA2310

Hello team,

Does signal input without power supply give damage to TLV9001?

(3V DC is input to input pin without power supply. The buffer configuration will be used for monitoring of battery voltage.)

Also do we have information the value of leakage current at input pin without power supply?

Best regards,

Shotaro

over 1 year ago

0 kai klaas69 over 1 year ago

Guru 140200 points

Hi Shotaro,

a schematic would be helpful.

Two things can happen: Damage and latch-up or lock-uo. Damage can be prevented by adding a suited current limiting resistor. See sections 7.1 and 10.1 of datasheet.

But when exceeding the common mode input voltage range additionally latch-up or lock-up can occur. I have discussed this topic here:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1097514/tlv9002-can-we-connect-ct-to-tlv9002

Kai

0 Clemens Ladisch over 1 year ago

Guru 243110 points

The inputs are diode-clamped to the power supply, so even with a current-limiting resistor, some current will flow from the input into the power supply, and can partially power up the TLV9001 or anything else connected to that supply.

You should use an opamp with overvoltage protection (OPA2206) or disconnect the signal with an analog switch.

+1 Jacob Nogaj over 1 year ago in reply to Clemens Ladisch

TI__Expert 8016 points

Hello Shotaro,

Clemens and Kai have covered the concerns regarding driving the inputs of the device while unpowered.

Here is a blog post demonstrating how an amplifier can become self powered through the input diodes: https://e2e.ti.com/blogs_/archives/b/precisionhub/posts/the-self-powering-device

I do not have any data on the leakage current with the given conditions. Input current exceeding 10mA can cause permanent damage to the device. I recommend limiting current in this condition to be less than 1mA.

You could use a shutdown device like TLV9001S to set the amplifier inputs and output to a Hi-Z state, allowing the input pins to be driven while the amplifier is unpowered + shutdown. Designing for TLV90xxS Operational Amplifiers With Shutdown

Alternatively, some devices such as the OPA2310 lack ESD diodes connecting the inputs to the V+ rail. This can allow positive voltage to appear at the inputs without ESD leakage to V+.