TPS61288: Efficiency difference between webench simulation and datasheet

Kazuki Kuramochi

Part Number: TPS61288

Hello Expert,

I have question for datasheet's measurement result.

Our customer is looking for boost converter for following condition.
Vin=2.8~4.6V
Vout=approx.20V
Iout= single-digit mA

Then I simulated some device using webench and I found this device due to this device has good efficiency at lower than 1mA as attached report.
TPS61288_SIM.pdf
However, this sim report's efficiency data has huge difference against datasheet's result.
For example, simulated efficiency is higher that 96% at 1mA load condition but measurement result(Vout=16V, Vin=3.6V) is approxf. 70%.
So we'd like to know about why there is such a huge difference between simulation result and datasheet.

Would you tell me the root cause of causing this difference?

Best regards,
Kazuki Kuramochi

over 3 years ago

0 Zack Liu over 3 years ago

TI__Mastermind 34201 points

Hi Kazuki,

Thank you for reaching out.

Please note TPS61288 maximum Vout is 18V. If customer wants a 20V Vout boost regulator, please consider using other device.

The WEBENCH efficiency data is calculated with equations and cannot match the real bench test results at all Vin/Vout/Iout conditions, especially at low Vin conditions. Please refer to TPS61288 datasheet efficiency curve.

0 Kazuki Kuramochi over 3 years ago in reply to Zack Liu

TI__Genius 9160 points

Hi Zack,

Thank you for your swift update.

I understood this device can support output voltage up to 18V.

For the difference between sim and datasheet, would you provide measurement circuit information of datasheet?
I agree that simulation main contain the factor that is cause difference but our focused area is low current load condition.
So, as I explained, external components may have impact for this difference.

Thank you and best regards,
Kazuki Kuramochi

0 Zack Liu over 2 years ago in reply to Kazuki Kuramochi

TI__Mastermind 34201 points

Hi Kazuki,

The datasheet efficiency is tested on TPS61288EVM. You can find the schematic and layout on TPS61288 EVM user guide.

0 Kazuki Kuramochi over 2 years ago in reply to Zack Liu

TI__Genius 9160 points

Hi Zack,

EVM's feedback resistor is configured for Vout=12.92V condition but I'd like to know about measurement condition during Vout=16V at efficiency measurement.
Would you provide it?

Best regards,
Kazuki Kuramochi

0 Zack Liu over 2 years ago in reply to Kazuki Kuramochi

TI__Mastermind 34201 points

Hi Kazuki,

We used same inductor, Cout for 16Vout efficiency measurement. Only the feedback resistor is changed to get 16Vout.

0 Kazuki Kuramochi over 2 years ago in reply to Zack Liu

TI__Genius 9160 points

Hi Zack,

As I explained, we focused efficiency at really low output current condition.
So we cannot ignore the current consumption from FB resistor.
Therefore, would you provide actual number when you measured efficiency on datasheet at Vout=16V case?

Best regards,
Kazuki Kuramochi

+1 Zack Liu over 2 years ago in reply to Kazuki Kuramochi

TI__Mastermind 34201 points

Hi Kazuki,

Bottom feedback resistor: 39.2kohm, Upper feedback resistor: 1000kohm

0 Kazuki Kuramochi over 2 years ago in reply to Zack Liu

TI__Genius 9160 points

HI Zack,

Thank you for your answer.
I get it.

Best regards,
Kazuki Kuramochi

Power management

Power management forum

TPS61288: Efficiency difference between webench simulation and datasheet