Thermal resistance values for Cyclone III devices are provided for a board
meeting JEDEC specifications and for a typical board. The JEDEC board
specifications require two signals and two power/ground planes and are
available at jedec.org The values are described in Tables 1through 4.

Table 1. Thermal Resistance Values for Cyclone III Devices
Value Description
θJA (C/W) Still Air Junction-to-ambient thermal resistance (θJA) with no
airflow when a heat sink is not being used.
θJA (C/W) 100
ft./minute
Junction-to-ambient thermal resistance with 100
ft./minute airflow when a heat sink is not being used.
θJA (C/W) 200
ft./minute
Junction-to-ambient thermal resistance with 200
ft./minute airflow when a heat sink is not being used.
θJA (C/W) 400
ft./minute
Junction-to-ambient thermal resistance with 400
ft./minute airflow when a heat sink is not being used.
θJC (C/W) Junction-to-case thermal resistance (θJC) for device.
θJB (C/W) Junction-to-board thermal resistance (θJB) for specific
board being used.