The average chip-junction temperature, TJ, in °C, can be obtained from the following equations:
From the first equation, the user can derive the estimated lifetime of the chip and decide whether a cooling device is necessary or not. If a cooling device has to be fitted on the chip, the second equation must be used to compute the resulting average chip-junction temperature TJ in °C.
Power usage can be calculated by adding together the system power consumption and the I/O module power consumption. The current drawn from pins with a capacitive load may be estimated (for one pin) as follows:
Icp ≈ VDD × Cload × fsw
Where Cload = pin load capacitance and fsw = average switching frequency of I/O pin.
Pin Count | Package Type | θJA (°C/W) | θJC (°C/W) |
---|---|---|---|
14 | SOIC | 58 | 26 |
14 | TSSOP | 95 | 20 |
20 | SOIC | 44 | 21 |
20 | SSOP | 60.6 | 25 |
20 | VQFN | 79.7 | 36 |
24 | VQFN | 60.6 | 25 |