AD7734 AD7732 calibration procedures

Question

Hi 
 
 May I know calibration procedure for AD7734 and AD7732? I still cannot figure out how to calibrate them.. Please tell me how to do step by step in software? Or you have software examples?

Best Regards 
 Thanks

JellenieR · Accepted Answer

Hi, 
 This thread and document below should guide you how to do the calibrations. 
 Calibration procedure for AD7734 - Q&A - Precision ADCs - EngineerZone (analog.com) 
 AD7732/AD7734/AD7738/AD7739 Calibration Registers Application Note (AN-663) (analog.com) 
 You can then use this driver as a starting point for your software. 
 https://wiki.analog.com/resources/tools-software/uc-drivers/renesas/ad7734 
 Thanks, 
 Jellenie)

JellenieR · Answer

Hi, I thought the attached link provided the step you are looking for. Hopefully i can make it simpler with these steps below. If both self-calibration and system calibration are used in the system, an ADC full-scale self-calibration should be performed first, followed by a system calibration cycle. Please take note that only one channel can be active during calibration, you can repeat the procedure when multiple channels are being used. It is also recommended to perform a reset upon initialization by writing 32 1s. Read back all register values to ensure that they are all at default upon power up. Self-Calibration It is strongly recommended not to change the ADC full scale register. Thus, for self-calibration a zero-scale self-calibration is only performed. To perform this, follow the steps below. 1. Configure the registers based on selected channel target configuration (i.e., enable, input range, conversion time). All other channels are disabled. You can readback the registers to make sure it was written correctly. 2. Connect the negative input terminal of selected channel to a valid common mode (e.g., 0V or GND) 3. Perform ADC Zero-Scale Self Calibration Mode. Write the relevant value to the mode register. 4. Wait for completion. You can either check the RDY bits in the status register, or monitor the /SYNC pin or wait until the ADC reverts to idle mode (you can also check this by reading the mode register) 5. Read the ADC zero-scale calibration register and check that the coefficient/value have changed from default value. 6. When calibration is complete, set the mode register to the required mode (e.g., continuous conversion mode or system calibration mode) Per channel system calibration. 1. Configure the registers based on selected channel target configuration (i.e., enable, input range, conversion time). All other channels are disabled. You can readback the registers to make sure it was written correctly. 2. Apply a fully settled zero scale voltage to the selected analog input channel (e.g., 0V) 3. Perform Channel Zero-Scale System Calibration Mode. Write the relevant value to the mode register. 4. Wait for completion. You can either check the RDY bits in the status register, or monitor the /SYNC pin or wait until the ADC reverts to idle mode (you can also check this by reading the mode register) 5. Read the Channel Zero-Scale System register and check that the coefficient/value have changed from default value. 6. When channel zero-scale system calibration is complete, removed the zero-scale input (0V) and apply a full-scale voltage to the selected channel (i.e., +10V, +5V depending on selected input range) 7. Wait for completion. You can either check the RDY bits in the status register, or monitor the /SYNC pin or wait until the ADC reverts to idle mode (you can also check this by reading the mode register) 8. Read the Channel Full-Scale System register and check that the coefficient/value have changed from default value. 9. When calibration is complete, set the mode register to the required mode (e.g., continuous conversion mode) After performing the system calibration you should see that your applied zero scale voltage or full scale voltage will corresponds to the code while the rest of the voltage level will be scaled accordingly. Thanks, 
 Jellenie

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AD7734 AD7732 calibration procedures

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