UCD3138A: UCD3138ARGCR

LITHIYASHREE KANNAN

Part Number: UCD3138A

Tool/software:

What is the resolution of the EADC differential pin of below mentioned part number. And how to calculate the adc error and adc count for the differential pin EAP1 and EAN1. I refered the ADC error calculation in the forum. But for differential how to calculate the adc error and count. Please share any calculation sheet available.

UCD3138ARGCR

over 1 year ago

0 Jonathan Wong over 1 year ago

TI__Genius 10595 points

Hello Lithiyashree,

Please see the below drawing for an explanation on how the EADC works.

Regards,

Jonathan Wong

0 LITHIYASHREE KANNAN over 1 year ago in reply to Jonathan Wong

Prodigy 90 points

Hi jonathan,

Thanks for image i understood the working of EADC. Is the reference DAC value do we need to set internally.

how to calculate the adc count and adc error.

Is EADC is 9 bit or 12 bit and what is reference voltage of the EADC. Here from DAC voltage is set do i need to inclue the DAC error also .

my EADC input voltage from the current sensor is 1.33 in EAP1 and 0 at EAN1 what the ADC will be the ADC count i will read in controller.

Please provide formula available to calculate the adc count and error for the EADC pin.

+1 Jonathan Wong over 1 year ago in reply to LITHIYASHREE KANNAN

TI__Genius 10595 points

Hello Lithiyashree,

Please see this E2E post that walks through a full example on how the 12-bit ADC is calculated: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1343727/ucd3138allcevm150-calculations-for-sensing-of-primary-current-signal-ips-and-calibration-in-firmware-for-the-same/5170546?tisearch=e2e-sitesearch&keymatch=%252520user%25253A525510#5170546

The DAC_VALUE can be used as your reference voltage to determine the EADC error. This is a register that you can set in the firmware.

The diagram that I shared above is a simplification on how the EADC calculation works. The purpose of the diagram is so that you can get a more intuitive understanding on how the UCD works. For a more in-depth explanation, please see the UCD Technical Reference Manual (TRM): https://www.ti.com/lit/ug/sniu028d/sniu028d.pdf. Specifically, section 3.2 on page 117 of the TRM walks through the Front End DAC and DAC_VALUE.

The EADC_RAW is a 9-bit signed integer. The count is only 6 bits and the extra 3 bits are shifted based on the AFE_GAIN to change the resolution. Please see section 3.1 on page 111 of the TRM for more information on the Error ADC and Front End Gain.

Regards,

Jonathan Wong

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UCD3138A: UCD3138ARGCR

UCD3138ARGCR