meterlib1ph_cfg I_MAX, U_MAX?

hyunwoochoi — Thu, 20 Aug 2015 22:15:07 GMT

Hello,

My project is based on _twr_emeter_demo(old one with KM34 128 series).

I can see a document: DRM143 Kinetis-M One-Phase Power Meter Reference Design.

Here is the question details.

Does U_MAX and I_MAX come from this schematic?

Then U_MAX should be 325.26V as it mentioned?

However, on page 25, it mentioned:286V not 325.26V.

I am not sure which value is correct one.

If my circuit use smaller register values such as two 150 Kohm instead of four 150 Kohm, then U_MAX value should be changed? then how?

There is no note about I_MAX though. Anyone know how to pick the value?

Thanks,

Hyunwoo

- page 25,

- page 13,

Re: meterlib1ph_cfg I_MAX, U_MAX?

Hui_Ma — Wed, 26 Aug 2015 05:44:48 GMT

The U_MAX has two factors could affect that value, one is the meter AC_DC SMPS related circuit design, which should match with the meter spec design requirement, the other one to meet the current measurement requirement.

The I_MAX value is based on hardware design and the ADC measure range (VREFH voltage), the ADC measurement value should not exceed the measure range to make current value in a range. The hardware schematics (shunt resistor value) also affect the I_MAX value, which also affect the U_MAX value.

Wish it helps.

Have a great day,
Ma Hui

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meterlib1ph_cfg I_MAX, U_MAX?

Re: meterlib1ph_cfg I_MAX, U_MAX?