| ??? 01/09/09 14:32 Read: times |
#161388 - Not 1.4W at 85C but 1.2-0.24 = 0.96W Responding to: ???'s previous message |
I don't know where you got the figure 1.4W from, but I think you read the datashseet wrong.
As long as the ambient temperature is no higher than 65C, you may power the chip in such a way that the total power loss may be up to 1.2W. But if the ambient temperature is higher than 65C, you must give the chip a lower supply voltage, because every degree higher ambient temperature requires you to reduce the power loss in the chip with 12mW. The reason is that at 65C ambient temperature, the chip will reach max allowed temperature at 1.2W power dissipation. With higher ambient temperature, it will take less power for the chip to reach max temperature. At 85C ambient temperature, the maximum allowed power dissipation in the chip is 1.2 - 20*0.012 W = 0.96W. This is similar to a normal resistor. It has a power rating that is valid up to a specified ambient temperature. But it also have a zero-power temperature where the ambient temperature is so high that you may not produce any internal warming of the resistor. |
| Topic | Author | Date |
| Thermal stress reduction for IC | 01/01/70 00:00 | |
| Ask the manufacturer! | 01/01/70 00:00 | |
| Wear from temperature cycling | 01/01/70 00:00 | |
| loose vs lose | 01/01/70 00:00 | |
| What's the rated MTBF? | 01/01/70 00:00 | |
| The temperature may rise | 01/01/70 00:00 | |
| automotive grade is 125C | 01/01/70 00:00 | |
| You should have mentioned 150C | 01/01/70 00:00 | |
| Why does it rise? | 01/01/70 00:00 | |
| Though its able | 01/01/70 00:00 | |
| Sounds unlikely to me | 01/01/70 00:00 | |
| You need to consume power to be able to save power | 01/01/70 00:00 | |
| Why not having some numbers? | 01/01/70 00:00 | |
| Power dissipation | 01/01/70 00:00 | |
| Not 1.4W at 85C but 1.2-0.24 = 0.96W | 01/01/70 00:00 | |
| figure 1.4W | 01/01/70 00:00 | |
| Reversed logic | 01/01/70 00:00 | |
| Agreed | 01/01/70 00:00 | |
| Answers | 01/01/70 00:00 | |
| The webpage accepts | 01/01/70 00:00 | |
| Useful links... | 01/01/70 00:00 | |
| Tjmax | 01/01/70 00:00 | |
| Please read the datasheet again, carefully! | 01/01/70 00:00 | |
Not Obsession only info | 01/01/70 00:00 |