Subject: Support Request for Current Sensing Calculation with VN9D5D20FN

[Vennila]

Hi, 

I am currently working with the VN9D5D20FN and RL78, successfully controlling 4 channels at a 100% duty cycle, achieving a 12V output. Now trying to read the current sense value for Channel 1 with OUTCFGR1 configured to 0x9FE0 and a rheostat load applied. I've readed the ADC values from the ADC1SR register and measured current consumption with a clamp meter.

Could you please assist me with the following:

1. How should I calculate the current value from the ADC1SR?
2. What is the K value in the Iout_conv formula for each channel?

Here are the ADC readings I have:

• ADC1SR = 0x0019 --> Current Value = ?
• ADC1SR = 0x001B --> Current Value = ?
• ADC1SR = 0x011C --> Current Value = ?
• ADC1SR = 0x021A --> Current Value = ?

Thanks and Regards,

Vennila

[Peter BENSCH · Accepted solution]

Welcome @Vennila, to the community!

The K values are listed separately in the data sheet for the various functions in tables 57, 58, 62 and 63.

The topic of K values is also discussed in detail in AN5792. In section 2 you will find a consideration according to which your measured current of 1...2A is within a fairly large tolerance range for K.

Hope this answers your questions?

Regards
/Peter

[Vennila]

@peter

I'm trying to find the K value. AN5792 will help me understand the K value.

Thanks for your support.

Regards

Vennila

[MasterT]

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