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In this video within the Introduction to the TIDA-010036 reference design section of the training series, we will discuss the features of the ADS131M04 standalone ADC and MSP432 metrology host microcontroller in the TIDA-010036 reference design. And this is on the ADS131M04 four-channel, simultaneously sampling, 24-bit, standalone, delta-sigma ADC is used. Each ADC channel consists of a delta-sigma oversampling modulator and a sinc cubed digital filter that modulates the output of the delta-sigma modulator by averaging.

For the ADS131M04, a clock is fed to its CLKIN pin. This clock is internally divided by 2 to generate the modulated clock, FM. The data passed through the filter is decimated or down-sampled to reduce the output frequency from the modulated frequency to the data rate, FS. The decimation factor is called the OSR.

This device supports a maximum data rate of 32 kilo samples per second. Each channel has an internal programmable gain amplifier that can amplify an input signal by up to 128, which enables this device to be connected to low output current sensors, such as shunts and Rogowski coils. The ADS131M04 is an acro ADC with a 101-dB dynamic range at a PGA gain of 1, which corresponds to an input voltage of 1.2 volts and 81 dB at a PGA gain of 64, which corresponds to an input voltage of plus or minus 18.75 millivolts.

At a gain of 1, the device exceeds requirements for a Class 0.1 accuracy across 10,000 to 1 input to current range. In addition, the ADS131M04 has low power measure modes that can be used to reduce device current consumption, which enables you to relax power supply requirements if a CAP draw power supply is used. There is also a low power current detection mode that can be used to sense meter tampering by removal of the meter's neutral connection.

The ADS131M04's ADC inputs are differential and can accept input signals below ground so that external level shifting circuitry is not needed when interfacing to voltage dividers and current sensors. Another feature of the ADS131M04 is that it has a programmable channel-to-channel phase delay, which can be used for phase calibration to cancel out any phase error between voltage and current samples that are introduced by the meter hardware. To ensure data integrity of the ADC data sent, the device also adds a CRC to the sent data packet, which can be used to verify the integrity of the packet that's being sent.

The MSP432P4111 device is used as the host microcontroller in this design. This is a 48-megahertz ARM Cortex M4F device with an eight-channel DMA that is used to communicate to the ADS131M04. The packet that is sent from the ADS131M04 has a CRC that's added to it.

The MSP432 calculates its own CRC by using its CRC module for accelerating CRC calculations. The two CRCs are compared to verify the integrity of the packets sent from the ADS131M04. The MSP432 also takes care of other application tasks, like driving the LCD, keeping track of time with its RTC module, and communicating to the PC GUI.