TPS61090 / About the value of L1.

Sho Ogane

Other Parts Discussed in Thread: TPS61090

Hi all.

The datasheet P14, P15 of TPS61090 shows the calculation of the L1 value.

●For example
・Vbat(Vin)=1.8V
・Vout=5V
・Iout=500mA
・ΔIL=IL*0.2

This datasheet shows that the value of L is 5.5uH.
Is this value correct?
I think the value is 6.6uH.

And could you tell me the value of the inductor L1 in the following case?
・Vin=1.8V
・Vout=5V
・Iout=0.4A

Best Regards,
Sho Ogane

over 10 years ago

0 Charles Wong1 over 10 years ago

TI__Intellectual 2270 points

please refer to the equations listed in the d/s, 5.5uH is correct.

0 Sho Ogane over 10 years ago in reply to Charles Wong1

Genius 5575 points

Charles san

Thank you for your reply.
Is the switching frequency used the typical value 600kHz?

This datasheet shows the calculation of the IL value.
I would like to know the meaning 0.8 of P14 (4).

Best Regards
Sho Ogane

0 Charles Wong1 over 10 years ago in reply to Sho Ogane

TI__Intellectual 2270 points

yes,
600Khz is the typical Fsw
0.8 is the efficiency of the converter

0 Sho Ogane over 10 years ago in reply to Charles Wong1

Genius 5575 points

Charles san

Thank you for quick response.

I understood 0.8 is the efficiency of the converter.
However, is the efficiency of TPS61090 over 90%?
This datasheet shows this device's efficiency is 96%.

Best Regards,
Sho Ogane

0 Charles Wong1 over 10 years ago in reply to Sho Ogane

TI__Intellectual 2270 points

i don't think you have read the datasheet carefully. when VIN=1.8V Vout=5V the efficiency is less than 0.9, we also need some margins to calculate the ripple. please refer to figure7 in the D/S.

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TPS61090 / About the value of L1.