Koheron Alpha250, User Manual

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Precision ADC
The precision ADC is a 8-channel, 24-bit sigma-delta ADC with programmable gain ampli er (Analog Devices AD7124-8
(http://www.analog.com/media/en/technical-documentation/data-sheets/AD7124-8.pdf)). The inputs differential pairs can be used
to sense either oating or ground referenced signal. They also facilitate Kelvin sense connections. Differential input voltage range is
± 1.25 V.
Alpha250 Precision ADC interface.
The rst four channels are available on the expansion connector. The next four channels monitor the offsets of the RF ADC and RF
DAC.
Communication with the precision ADC is done through a dedicated SPI bus. The precision ADC data can be retrieved using the
PrecisionAdc driver (https://github.com/Koheron/koheron-sdk/blob/master/boards/alpha250/drivers/precision-adc.hpp).
Precision DAC
The precision DAC is a 4-channel, 16-bit DAC (Analog Devices AD5686 (http://www.analog.com/media/en/technical-
documentation/data-sheets/AD5686_5684.pdf)).
The output voltage ranges from 0 to 2.5 V. It includes an output buffer that can deliver up to 20 mA per channel. The outputs are
ESD protected.
Alpha250 Precision DAC interface.
The four output channels are available on the expansion connector. Communication with the precision DAC is done through a
dedicated SPI bus via the PrecisionDac driver (https://github.com/Koheron/koheron-
sdk/blob/master/boards/alpha250/drivers/precision-dac.hpp).
Temperature sensors
The Alpha250 has two high-accuracy temperature sensors (TMP116 (http://www.ti.com/lit/ds/symlink/tmp116.pdf)) with an
accuracy of ± 0.2 °C over -10 °C to +85 °C. One sensor is placed near the voltage reference (T0 highlighted in blue) to allow
temperature compensation in high precision measurements. The other one is placed between the clock generator and the RF ADC
which is close to the hottest point on the board (T1 highlighted in red).\