Actel Silicon Explorer II User Manual page 40

Appendix D: Troubleshooting
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Q: How is the checksum of the device read?
A: The checksum of most devices is read through the SDO pin. For
information about the location of SDO pins in all Actel Devices
please refer to "Location of the SDO Pin" on page 21.
ACT1 and the 40MX pins do not have an SDO pin. In order to read
the checksum from ACT1/40MX devices the PRA on the device
must be connected to the SDO pin of the Silicon Explorer.
Q: What are the power requirements for Silicon Explorer II?
A: Silicon Explorer II must be connected to a power supply of 5V for
5V tolerant devices, 3.3V for 3.3V tolerant devices, and 2.5V for
2.5V tolerant devices.