TPS564208: Ambient TEMP

Tommy Tzeng

Part Number: TPS564208

Hi Sir,

may we know the operating ambient temperature range of TPS564208? beacuse the customer has following confuse.

Can reconfirm that MAX TA (=guarantee operating temperate) value is 125 degree C?

customer can’t believe this value for 125 degree C, because of the data sheet specification shown as Tj MAX for 150 degree C and Tj recommended for 125 degree C only.

We see that the operating temperature specification of most other vendors is only written to 0~85degreeC.

I have highlighted this TI specification for Tj as below,

I have highlighted other vendor specification for Ta and Tj as below,

over 4 years ago

0 Vincent Zhang(BSR) over 4 years ago

TI__Expert 4795 points

Hi Tommy,

For IC Ta is not important why Tj is. The supporting Ta depends on what's current load added on IC.

For example, if customer run TPS564208 always at 0A, then they can use at 125C Ta condition.

If customer run TPS564208 always at 4A, then maybe they can only use it at 85C Ta condition.

The key is not exceed 125C Tj.

0 Raymond Liao over 4 years ago in reply to Vincent Zhang(BSR)

Prodigy 60 points

Dear Sir,

We want to know the real Ta parameter value at 4A condition for full load mode, please reconfirm it.

If the Ta is 85C for right value as the same other vendor, please help to make sure it.

Because of we need provide the comparison table with main source and 2^nd source to our customer.

BTW, Ta also needs to provide the minimum operating temperature.

tks!

Raymond

0 Vincent Zhang(BSR) over 4 years ago in reply to Raymond Liao

TI__Expert 4795 points

Hi Raymond,

Based on 1 oz/1oz thickness two-layer board, For 4A condition, the maximum Ta is 45C.

12V->3.3V/4A condition, maximum Ta is 45C, then Tj is 122C;

12V->3.3V/3A condition, maximum Ta is 70C, then Tj is 125C.

If you choose 2oz/2oz layer board, maximum Ta could be higher becasue the board heat dissipation capability is better.

Minimum Ta is -40C.

0 Raymond Liao over 4 years ago in reply to Vincent Zhang(BSR)

Prodigy 60 points

Hi Vincent,

Please help to provide this result based on 1oz/1oz thickness four-layer board, For 4A condition.

I hope get the same result with competitor.

I have shared below result of competitor for your reference,

Ta=-40~85C

tks!

Raymond

0 Vincent Zhang(BSR) over 4 years ago in reply to Raymond Liao

TI__Expert 4795 points

Hi Raymond,

What's competitor part?

0 Raymond Liao over 4 years ago in reply to Vincent Zhang(BSR)

Prodigy 60 points

Hi Vincent,

This competitor part is RT6278 (@8A), and I have shared the specification as below,

Another competitor part is SY8104 (@4A), and I have shared the specification as below,

tks!

Raymond

0 Vincent Zhang(BSR) over 4 years ago in reply to Raymond Liao

TI__Expert 4795 points

Hi Raymond,

For RT6278, it could support higher temperature, becasue it's RDSON is lower so efficiency is higher/dissipiation is lower at 4A condition.

For SY8104I, from my understanding, I don't think it could support Ta=85C at 4A condition.

From datasheet, the efficiency is 92% at 12V->5V/4A condition. The loss is around Ploss=5*4/0.92*0.08=1.74W. Suppose Inductor loss is 0.3W, IC loss is about 1.44W.

From its EC table, Theta-JA is 56C/W. So the temperature rise is 1.64w x 56C/W=80.64C. The allowed maximum Ta is 125C-80.64C = 44.36C.

Some devices we describe Ta = -40C~85C but actually couldn't support full loading at 85C, it is easy to calculate by efficiency/Ploss/Theta-JA.

To compare two parts' actual maximum ambient temperature,

You can compare the package/efficiency/Maximum Tj. If package is same, Tj_max is same, the maximum allowed Ta should be similar.

Please send me email: wuyang-zhang@ti.com if you have further questions about this topic.

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TPS564208: Ambient TEMP