INA240: high side current detection, rising and falling edge voltage spikes at output of INA240

Yue TANG

Part Number: INA240

Hi,

my customwer want to do high side current dection in a motor drive application (using DRV83002). so far, they are testing this function with our INA240A2EVM. bus voltage is about 24V, 75A peak.

but the PWM rejection of this device didn't seem to work,below is waveform of the oscilloscope， please kindly suggest what may go wrong? thanks.

input :

output:

over 4 years ago

0 Gerald Steele over 4 years ago

Prodigy 210 points

One thing to consider, amplifiers are only part of the problem (and the amplifier may not be the problem here).

Most shunt applications need correct input filtering to compensate for shunt inductance.

More details here:

https://www.planetanalog.com/current-shunt-resistor-inductance-it-matters/#

0 Guang Zhou over 4 years ago in reply to Gerald Steele

TI__Mastermind 29740 points

Hi Yue,

Can you please label the horizontal and vertical scales of the scope shots?

I’m guessing “input” is measured from one input pin relative to ground? For now I’ll assume it is and therefore this is a typical in-line configuration, not high side. Please correct if this assumption is no right, same below.

I further assume that customer is concerned with the spikes found near the edges. Wiring in an EVM for inline measurement is problematic and can’t be used as a direct indication of the device performance. PCB layout plays an important role. Also, please remove the two Zener diodes from the input. This sometimes helps reduce the spikes.

Regards, Guang

0 kai klaas69 over 4 years ago in reply to Guang Zhou

Guru 140200 points

Hi Jue,

I agree with Guang, something is wrong with the measurement setup. Improve your signal ground routing by finding a better signal ground connection point. Also minimize all involved cable lengths. Use a scope probe with such a ground spring: