SN65DSI84: Document for Tj

Len Hsu2

Intellectual 2440 points

Part Number: SN65DSI84
Other Parts Discussed in Thread: TS5A21366,

Hi team,

Here I have customer for IPC application that they want some information about Tj.

There have information about Ta and Tcase , and they want some information for Tj

Thanks for your help.

over 4 years ago

0 Ikechukwu Anyiam over 4 years ago

TI__Mastermind 35130 points

Hi Len,

What specific information about Tj are they looking for? There is thermal information for this device available in the Thermal Information section of the datasheet.

Regards,

I.K.

0 Len Hsu2 over 4 years ago

TI__Intellectual 2440 points

Hi I.K,

Thanks for your reply.

For now they have Tc and Ta information from datasheet.

And they want to know the range about Junction Temp, is there any information or formula for this?

Best regards,

Len

+1 Ikechukwu Anyiam over 4 years ago in reply to Len Hsu2

TI__Mastermind 35130 points

Hi Len,

Tjmax can be estimated with Tjmax= Ambient Tempmax + Pmax(RθJA), so for the DSI84 it's about ~93C.

Regards,

I.K.

0 Len Hsu2 over 4 years ago

TI__Intellectual 2440 points

Hi I.K,

Thanks for your reply.

The customer feedback that they had used many ICs and they observed that most of Tj and Tc have around 3+ degree deviation (Tj > Tc around 3C degree or above)

But in this case, it’s only 0.7C degree higher. Is that right?

If the following formula is TI chip standard?

+1 Ikechukwu Anyiam over 4 years ago in reply to Len Hsu2

TI__Mastermind 35130 points

Hi Len,

It is just an approximation. Customer can reference this FAQ for more details: e2e.ti.com/.../167939

Regards,

I.K.

0 Len Hsu2 over 4 years ago in reply to Ikechukwu Anyiam

TI__Intellectual 2440 points

Hi I.K,

Thanks again for your reply and suggestion.

And I got some feedback from the customer, the link you provide is TS5A21366, and the information could be understand.

But the material can't be meet to SN65DSI84 SPEC

He only found Vmax (Vcc), & RꙨJa in datasheet , and he also question about VCC unit, he thinks it's too much.

And why TS5A21366's Ta = 85C Tj = 113.3C (it make sense), but SN65DSI84's range is so small?

Best regards,

Len

+1 Ikechukwu Anyiam over 4 years ago in reply to Len Hsu2

TI__Mastermind 35130 points

Hi Len,

Pmax for the DSI84 is only Vcc*Icc = 1.95 V * 150 mA = 0.2925 W.

Max ambient temperature is 85C.

RθJa = 55.1 C/W

So Tjmax= Ambient Tempmax + Pmax(RθJA) = 85 + 0.2925*55.1

=101.1 C

Regards,

I.K.

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SN65DSI84: Document for Tj