topic 回复： mm9z1j638 in S12 / MagniV Microcontrollers

mm9z1j638

cui1 — Fri, 12 Jan 2024 09:55:59 GMT

Hello engineer!
I used the Shunt value for this parameter in the Vin of the look Current calculation company
These are the only shunt values I saw in the manual, but my actual Shunt value is 70uohm
What I want to know is if it's affecting my current measurements

回复： mm9z1j638

cui1 — Fri, 12 Jan 2024 10:08:23 GMT

回复： mm9z1j638

Q_man — Tue, 16 Jan 2024 07:24:03 GMT

Hi,

the idea of the shunt selection is to have a fixed 1mA/LSB of the actual ADC reading. We call this formating of the output value.

The ADC itself does always operate the same independent of the formating.

I suggest to use the standard configuration of 100uOhm, which has a 0.1uV/LSB result.

You shunt provides 70uV/A which would be 700LSB /A or ~1.43 mA/LSB.

Rgds
W.

回复： mm9z1j638

cui1 — Tue, 16 Jan 2024 08:45:02 GMT

Thanks! But our maximum current value may reach 1500A, may I ask if 100uOhm has any effect?

回复： mm9z1j638

Q_man — Tue, 16 Jan 2024 09:08:34 GMT

the 1500A with a 70uOhm is no issue.

回复： mm9z1j638

cui1 — Tue, 16 Jan 2024 09:12:34 GMT

Thanks! What I want to say is is it ok for the Shunt of 100uOhm to be at a maximum of 1500A? Is there any relevant calculation formula?

回复： mm9z1j638

Q_man — Tue, 16 Jan 2024 09:20:18 GMT

the 1500A with the 100uOhm shunt results in 1500A*100uV/A = 150mV.

In the datasheet we limit the differential input voltage to 150mV:

with 1500A on a 70uOhm will result in 105mV.