| 26.2 Effects Of Power Dissipation |
| When power is dissipated, it invariably leads to rise in temperature of the chip. This rise in temperature affects the device both when the device is off as well as when the device is on. |
| |
When the device is off, it leads to increase in the number of intrinsic carriers,  by the following relation: |
|
(Eq 26.1) |
| From this relation it can be seen that as temperature increases, it leads to increase in the number of intrinsic carriers in the semiconductor. The majority carriers, contributed by the impurity atoms, are less affected by increase in temperature. Hence the device becomes more intrinsic. |
| |
| As temperature increases, leakage current, which directly depends on minority carrier concentration, increases which leads to further increase in temperature. Ultimately, the device might break down, if the increase in temperature is not taken care of by time to time removal of the dissipated heat. |
| |
A ON device wont be affected much by minority carrier increase, but will be affected by  and  which decrease with increase in temperature and lead to change in  . Hence the device performance might not meet the required specifications. |
| |
| Also, power dissipation is more critical in battery powered applications as the greater power dissipated, the battery life will be. |
