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Please can anyone point me in the direction of the Tj max for the TS5A21366 Analogue Switch?
This data is not in the datasheet, and is needed for derating the part in my application. The only information is the max ambient temperature, and the theta JA, so I can loosely approximate what the junction will rise to, but not the maximum allowed temperature of the junction.
Please refer to this application note Semiconductor and IC package thermal metrics
It is best if you use the RθJA value as a way to compare parts versus using the value as an absolute since the customer’s system PCB design will highly influence this number as stated above.
But if you must have a number using this calculation Tjmax= Ambient Tempmax + Pmax(RθJA) here it is below:
Signal Switch power dissipation and junction temperature calculator.xlsx
The max power for the TS5A21366 can be calculated by
Pmax = (V+max)(I+max) + 2*[(Ino,Inc,Icommax)^2(Ron)]
About 112mW = (5.5 V)(10uA) + 2[(200mA)^2(1.4 Ohm)
Tjmax= Ambient Tempmax + Pmax(RθJA)
Tjmax = (85°C) + (112mW)(253°C/W)
Tjmax = 113.3°C
113.3°C is an approximation of the maximum junction temperature that the device can obtain while operating at its maximum recommended values. The datasheet abs max table states that max storage temperature for the device is 150°C which is well above 113.3°C. This will mean that there is little risk of thermally causing damage while running this part to its maximum recommended values.
In reply to Adam Torma:
This response seems to be imply that - (1) the Max Storage Temp and the Max junction Temp are equivalent, in that (2) no damage will occur while powered- up to the max storage temperature and that (3) the part will also operate- up to the max storage temperature, (4) and not experience any reliability issues (such as reduced life). Are all of these statements true for the SN74CB3Q32245ZKER & SN74CB3Q3245RGYR?
In reply to Matt Crum:
In reply to Jason Rubadue:
If the datasheet doesn't rate the performance of the device at 105 deg C ambient temperature range TI cannot gaurnutee the device performance stated in the datasheet
TI can undertake the effort to characterize the device at higher temperature range but we need to make sure there is the correct business opportunity to offset the cost of properly ensuring the device operation at higher temperature.
There is a way to search for switches and multiplexers on TI.com based on ambient temperature rating. There are 61 switches that can support > 85 deg C ambient temperature. What do you think about the CD4066B or SN74CB3T16210-Q1?
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