WEBENCH® Tools/TIDA-01513: Isolation Res calc

Hi Rami,

It's great that you used reference design TIDA-01513 for insulation detection.

Firstly, please update the resistor value for the high pack voltage high up to 1000V. Otherwise, the voltage will beyond the range of the AMC1301 and OPA.

Here attached the formula of how to calculate isolation resistance of both Risop and Rison. And how ISO_POS and ISO_NEG are calculated.

Will revise the TIDA-01513 spec to add this formula as well.

TIDA-01513 calculation formula for two points leakage (Bidirectional cal....pdf

Hi Rami,

I have a urgent business trip and I will turn back to you quickly as I am back. Sorry for that.

Hi Rami,

I am back from the business travel. Sorry for the delay.

α is the voltage at HV battery positive terminal refer to Chassis ground when S1 is 'ON'.

β is the voltage at HV battery negative terminal refer to Chassis ground when S2 is 'ON'.

Equation1 and equation2 are derived using the Kirchhoff laws when either S1 or S1 is 'ON'. Just use the assumption that no input current to OPA and voltage at IN+ equals to IN-. 

Thanks for the explanation

in the below formulae , i need HV_BATT2 and HV_BATT1 also to calc isolation resistance.

How to calc these is not explained in your attached file

i want formuale to calc isolation res, with help of ADC i am reading from op-amp (ISO_POS, ISO_NEG)8176.TIDA-01513 calculation formula for two points leakage (Bidirectional cal....pdf

Hi Rami,

HV_BATT is HV battery measurement in our reference design TIDA-01513.  You can refer to the path AMC1301-Q1 and OPA320 as well.

HV_BATT1 is the HV battery measured when S1 is 'ON'. And HV_BATT2 is the HV battery measured when S2 is 'ON'.

We consider the HV battery can vary during the operation.

Hi Rami,

It can't do the Isolation resistance calculation without HV battery measurement.

You can only do very draft leakage judgement without HV battery reading.