AN 773: Drive-On-Chip Design Example for Intel® MAX® 10 Devices

ID 683072
Date 4/22/2021
Public
Document Table of Contents

5.1. Signal Sensing in Sigma-Delta and MAX 10 Integrated ADCs

The Drive-On-Chip Design Example for Intel® MAX® 10 devices configures the Intel® MAX® 10 ADCs as a dual ADC with sequencer and sample store using the internal 2.5 V reference. It uses 16 channels, channels 1 to 8 on each of the ADC submodules.

Each Intel® MAX® 10 ADC submodule converts the 8 input channels in sequence. The Intel® MAX® 10 ADC Qsys component configures the sequence. Intel chooses the order in which the design connects signals to the ADC inputs. Also, Intel chooses the sequence in the Qsys component to minimize the time difference between the most recent feedback current samples for motor control.

Sigma-delta modulators on the power board convert analog signals to a one-wire digital bitstream. The design demodulates or filters the bitstream in the FPGA. The FPGA uses two types of sigma-delta filter IP in the FPGA, ADC modules and DC link modules, each with different scaling and offset.

The design downloads and filters all sigma delta inputs in parallel so no skew exists between the samples that it feeds to the software application.

Each ADC type has a different input and output ranges with the corresponding 'C' data type..

Table 5.  ADC Output Data
ADC Type Input Range Count Range C Data type
Sigma-delta ADC -320…+320mV -32768…+32767 Signed 16-bit
Sigma-delta DC link 0…+320mV 0…+32767 Unsigned 16-bit
MAX 10 0…2.5V 0…4097 Unsigned 16-bit

The input current and DC bus current are only available via sigma-delta ADCs.

Position feedback samples are scaled to a 23 bit unsigned integer, for consistency across all encoder types supported by this and previous Drive-On-Chip reference designs.

Table 6.  ADC ScalingThis table shows the ADC scaling for all signals, ADC type and board revision. The scaling depends on the way the power board processes the signals (e.g., value of current shunts, scaling, and offset in sense amplifiers).
Feedback Quantity Sigma Delta Interface IP Sigma Delta Scaling for Tandem Motion Power Board Intel® MAX® 10 Scaling for Tandem Motion Power Board
Motor Phase Voltages ADC interface 545 counts/V 67.7 counts/V
DC Bus Voltage ADC interface 40 counts/V 67.7 counts/V
Input Voltage DC Link 895 counts/V 223 counts/V
Input Current DC Link 256 counts/A N/A
DC-DC Inductor Current ADC interface 717 counts/A 57.3 counts/A
DC Bus Current DC Link 1638 counts/A N/A
Motor Phase Currents ADC interface 1024 counts/A 81.9 counts/A

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