TPS61041-Q1: Calculation method of average consumption current at 125 ° C

Koji Hayashi92

Mastermind 7030 points

Part Number: TPS61041-Q1
Other Parts Discussed in Thread: TPS61041, , TPS61040

Hi All,

My customers want to know how to calculate average current consumption at 125 ° C

Since there is no WEBENCH of TPS61041-Q1, they was checked with TPS61041.

WENBENCH only supports up to 85 ° C.

Please tell me how to calculate the average current consumption under the following conditions.

Vin=3.06 Vout=20V Iout=0A Temp=125℃

Best Regards,
Koji Hayashi

over 7 years ago

0 Helen chen over 7 years ago

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we also didn't have this data. It is determined by the inductor, output cap, output dividing resistor they chosen. suggest they apply for a TPS61041 EVM board, change the component to what they needed, then test it in the thermal Chamber.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

Thank you for quick response.
I will propose the measurement to the customer.

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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Thanks!

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

Since they do not know the variance in EVM, is there data on IC current consumption at high temperature?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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Do you mean the Iin @ Vin=3.06 Vout=20V Iout=0A Temp=125℃?

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

Condition
・Vin=3.06V
・Vout=20V
・Iout=3mA

If possible, check the consumption current for each temperature with the horizontal axis temperature and the vertical axis current.
My customer is concerned about an increase in current consumption at high temperature.
It seems that they want to check current consumption at ambient temperature up to thermal shutdown.

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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OK, will do it, but needs some times since the thermal chamber need to book in advance.

0 Helen chen over 7 years ago in reply to Helen chen

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Please check the below data at different temperature. The input current will increase at high temperarure.

Iin(mA) Temp©

26.25 -25

26 0

25.88 25

26.9 50

31.67 75

36.16 85

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

Thank you for quickresponse.

How about 125 ℃?

What's more?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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It is 55.1mA

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

Thank you for response.

Does the current rise linearly even at 125 °C or more ?
Is there a possibility of a rapid increase ?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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just tested to 125C. We can make the IC work at 125C for a long time to check it.
We're out of office and will back to office after Feb 22th. Please wait in patient.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

It is an additional question.

I think ,this value was mesured EVM.

What is the maximum value when considering IC variability ?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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yes, the value is measured on the EVM.For the IC variability, I'll check with the design team after back to office.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

Thank you for the quick reply in spite of a holiday.
Hope to hear from you soon.

Best Regards,
Koji Hayashi

0 Koji Hayashi92 over 7 years ago in reply to Koji Hayashi92

Mastermind 7030 points

Hi Helen-san

There may be changes in input voltage, output voltage, load current from the condition measured the other day.

Is there a method to calculate the current consumption other than the method of measuring?

I hope WEBENCH can support 125C.

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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I'll check with the Webench team.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

When will the results confirmed by the design team be contacted ?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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For the TPS61041-Q1, the Rdson of the low side FET has big relationship with the temp, the Rdson of the low side FET at 125C is at least around two times the 25C condition. Please check the below data.

For the TPS61041 EVM board, it also has an inductor on the board, the DCR of the inductor at high temp also much higher than the 25C condition. So you can found @ 125C Iin increased nearly by two times compared to the 25C condition.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

Thank you for response.

Since the current consumption at 25C is 25.88 mA, is 51.76mA correct when considering IC dispersion ?

Is it impossible to present consumption current of 125C or more ?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

TI__Mastermind 40080 points

51.76mA is not so correct, since the Rdson of different IC has tolerance. and the inductor also have some tolerance. As what I tested, it should be around 55mA. If they choose a better inductor, then the Iin will be a little bit smaller. Why they need such accurate value? For the power IC on the EVM board, Iin usually has big tolerance.

Yes, It is impossible to give out the consumption current of TPS61041 at 125C. The consumption will have big tolerance, the tested value is more accurate.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

When IC variations are added, how is it at 125C ?
Is this also unable to answer?

From the measurement result, the current consumption at 125C is about 1.5 times of 85C.
Is it a mistake to estimate that WEBENCH's 85C result will be multiplied by 1.5?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

TI__Mastermind 40080 points

You can make this assumption, but may not so accurate.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

Thank you for response.

About consumption current in consideration of variations in IC, was there a response from the design team?

Best Regards,
Helen

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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I checked with the design team, they replied that the main consumption is the internal MOSFET loss. The consumption of the internal control circuit VS. the temp. changes a little.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san
Thank you for quick response.

I try calculate using Datasheet and www.ti.com/.../slva390.pdf.
I will compare the calculation result with your measurement result.
Have you changed the coil of the EVM ?
Is it 10uH ?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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It is not 10uH inductor, it is a 22uH inductor. Why you calculate it instead of test it? test result is more trustable

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

The customer's specifications have not been fixed yet, so the conditions change.

There are four condition candidates.

Is it possible to measure after telling the condition?

Also, 55 mA is the measured value.

How many do you get with variations?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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We can measure it! I think the variation is around +-10%.

0 Helen chen over 7 years ago in reply to Helen chen

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But they can take 20% variation for worst case assumption.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

Thank you for quick resoponce.

I will reply to customers that IC variation is ± 20%.

Additional conditions are shown below.

Temp:-25,0,25,50,75,85,125

No.	1	2	3	4
Vin [V]	3.56	3.56	4.66	4.66
Vout [V]	20.21	20.21	18.19	18.19
Iout [mA]	6.5	4.81	3.16	1.98

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

TI__Mastermind 40080 points

Thanks, I'll book a time and test it. Please wait in patient.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

How is the evaluation situation?
When can I get the results?

What is the cause of 20% of consumption current variation at 125C?
Is it Frequency or Coil?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

TI__Mastermind 40080 points

Will give the resullt to you today. 20% varition is mainly from the inductor side.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san
Thank you for quick response.

I understood that the inductor DCR variation and product variation are the causes.
Is it correct?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

TI__Mastermind 40080 points

Hi,

Please chekc the attached result. I only give the eff and Iin from -25C to 85C. because I found I use a 85C inductor during the test, And we didn't have the 125C idnuctor in hand now.

The supplier will give the 125C inductor to us soon.

I'm so sorry for this. tps61041 eff with 10uH inductor .xls

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

Thank you for quick response.

Is the measurement result of the previous time also an inductor of 85C?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

TI__Mastermind 40080 points

Yes, the previous result is a 22uH inductor of 85C rating. Now I use a 10uH inductor. The new 125C 10uH inductor will arrive two days later. I will send the new result to you before the end of Friday.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

I saw the your evalution result.

Evaluation conditions are partially different.

I would like you to measure Vin = 4.86V and Vout = 18.19V.

However, you measured Vin = 4.86V and Vout = 20.21V.

Is it possible to measure by changing the output voltage ?

Please tell me the model number of the inductor to calculate the loss of the inductor.

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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OK. We'll retest it after we got the 125C inductor. the inductor will arrive at Friday morning.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

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Hi Helen-san

How is the situation here ?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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We found something abnormal even change the inductor to a 125C rating inductor, very high input current and the output volatge drops. Is checking what's wrong. Will update to you once we got the answer. Really sorry for this.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

How is the state of progress after that ?

When can I obtain measurement results ?

Customer is in the process of examining whether to use TPS61041-Q1.

There are additional evaluation conditions.
Vin=3.56V
Vout=20.21V
Iout=3.09mA,7.14mA

First of all, please give me the measurement result of the previous condition.

I think that there is a possibility that the measurement result will not come out because you are investigating the cause.
I would like to calculate in advance and put it out.

I think like this from past interactions.
Maximum value of current consumption = TYP value of current consumption × 2 × DCR variation.

Is it correct?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

TI__Mastermind 40080 points

Wil try to give the data to you tomorrow. But only the data under 85C, we found abnormal at >85C condition.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

I am waiting for the measurement result.
Is it possible to measure 125C ?
I would like to predict 125C from the measurement result,does the following calculation formula match ?
Maximum value of current consumption = TYP value of current consumption × 2 × DCR variation.

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

TI__Mastermind 40080 points

We found the input current getting very large at 125C condition. which is abnormal, we need to check the root cause. will update to you once we found the root cause.

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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We're determine the root cause and guess maybe the leakage current of the output diode cause the reason. At high temp, the leakage current will even higher than the load current.

Please check the below curve. I'll change to a signal diode to chekc it again.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

Do you plan to measure by changing diodes?
When can I obtain measurement results?

Is the above formula correct?
If it matches, I will calculate from the result of 25C , so can you give the result of 25C of additional condition?

Best Regards,
Koji Hayashi

0 Helen chen over 7 years ago in reply to Koji Hayashi92

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Yes, I plan to change the diode, the leakage current of the schottky diode at the high temp is too much , even bigger than the load, so the previous test is meaning less at high temp. so I'll test the eff from 25C to 125C again with new fast swithing diode.
The thermal chamber need to be booked. I can use the chamber tomorrrow. So the result will come out tomorrow. Really sorry for this.

0 Koji Hayashi92 over 7 years ago in reply to Helen chen

Mastermind 7030 points

Hi Helen-san

Please attach the BOM list and evaluation setting status when attaching data .

Best Regards,

Koji Hayashi.

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TPS61041-Q1: Calculation method of average consumption current at 125 ° C