TLV379: Amplifiers forum

HARINI KRISHNA

Expert 1905 points

Part Number: TLV379

Hi, we are following https://e2e.ti.com/blogs_/archives/b/precisionhub/archive/2016/07/15/how-to-design-cost-sensitive-battery-monitoring-circuits and using TLV379 and ADC channel of NRF52832 to measure battery voltage. We already discussed this with TI engineers and as suggested we placed a low pass filter between the op-amp output and the ADC channel

https://e2e.ti.com/support/amplifiers/f/14/p/895244/3310584#3310584.

when we measured the voltage at the output of the amplifier ( after the low pass filter) we are observing a 200mV drop.

i am attaching the schematic below

R47 is not connected.

Can you please suggest on this design?

Thank-you

Warm Regards

Harini Krishna

over 3 years ago

0 Caro Walter over 3 years ago

TI__Genius 17487 points

Hello Harini,

The image of the schematic you have attached seems to have not properly loaded.

Can you please attach it again?

All the best,
Carolina

0 HARINI KRISHNA over 3 years ago in reply to Caro Walter

Expert 1905 points

Hi Carolina,

Hope you are doing good.

I apologize for the bad file

Please find the schematic attached below

Thank-you

Warm Regards

Harini Krishna

0 HARINI KRISHNA over 3 years ago in reply to HARINI KRISHNA

Expert 1905 points

Hi,

Hope you are doing good.

Can you please suggest on the design?

Thank-you

Warm Regards

Harini Krishna

0 Caro Walter over 3 years ago in reply to HARINI KRISHNA

TI__Genius 17487 points

Hey Harini,

I am sorry for the late response as I changed the email notifications on e2e and I never got an email that you had responded. Can you tell me what voltage is at TP16?

Additionally, can you specify what you mean by "when we measured the voltage at the output of the amplifier ( after the low pass filter) we are observing a 200mV drop". Can you in depth tell me where you are measuring to attain this voltage drop?

All the best,
Carolina

0 HARINI KRISHNA over 3 years ago in reply to Caro Walter

Expert 1905 points

Hi Carolina,

Good day..!

The Test point TP16 with respect to ground measures the input to the TLV379idr. We are converting 0-12.6 V battery voltage to 0-2.5 V through the resistor divider. based on the input voltage, TP16 ( with respect to ground) will read anywhere between 0-2.5 V
We did not solder R47 ( 0 ohm resisitor). When we are measuring the voltage at J8, we are observing a 20mV ( I apologize for the mistake in the previous post) drop from the actual value. ( if the voltage at TP16 is 2.34V, at J8 we are reading 2.32V)

Thank-you

Warm Regards

Harini Krishna

0 kai klaas69 over 3 years ago in reply to HARINI KRISHNA

Guru 140200 points

Hi Harini,

and R48 is 10k?

Kai

0 HARINI KRISHNA over 3 years ago in reply to kai klaas69

Expert 1905 points

Hi Kai,

Yes, R48 is 10k

Harini

0 kai klaas69 over 3 years ago in reply to HARINI KRISHNA

Guru 140200 points

Hi Harini,

R48 and the impedance of voltmeter can form a voltage divider. This could explain the voltage drop.

Kai