TPS61086: Input separation

Takashi Yamaguchi

Genius 14855 points

Part Number: TPS61086
Other Parts Discussed in Thread: TPS61089, TPS61175, LMR62014

Hi team,

My customer would like to use the TPS61086 for the following condition.

Vin=5-9V

Vout=9V

Iout=600mA

Does TPS61086 allow to separate input rail as shown below? According to the d/s, Vout needs to be high at least 0.5V than Vin, so I think that Vin(max) would be 8.5V.

Regards,

Yamaguchi

over 5 years ago

0 Zack Liu over 5 years ago

TI__Mastermind 34251 points

Hi Takashi,

Actually they can use LMR62014, TPS61089 or TPS61175 for this application.

0 Takashi Yamaguchi over 5 years ago in reply to Zack Liu

TI__Genius 14855 points

Hi Zack,

Thank you for the proposal. Do you have the min duty cycle or Ton(min) information for these devices? Or do you have a device which has bypass Mode pass-through mode to support Vin=9V, Vout=9V?

Regards,

Yamaguchi

0 Takashi Yamaguchi over 5 years ago in reply to Takashi Yamaguchi

TI__Genius 14855 points

Hi Zak,

I found following e2e post about LMR62014. It seems that LMR62014 can work even Vin is close to Vout.

https://e2e.ti.com/support/power-management/f/196/p/692929/2556522?tisearch=e2e-sitesearch&keymatch=lmr62014%2520pass#2556522

Regards,

Yamaguchi

0 Zack Liu over 5 years ago in reply to Takashi Yamaguchi

TI__Mastermind 34251 points

Hi Yamaguchi,

Boost devices have minimum Ton limitation. When Vin is close to Vout, the needed duty cycle should be very small according to equation: D=1-Vin/Vout.

So for LMR62014, it will switch for several pulses, output voltage is increased then it stops switching until output voltage drops to setting value. Thus output ripple is large. If customer could accept that, LMR62014 should be one choice.

TPS61089 output ripple is also large when Vin is close to Vout.

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TPS61086: Input separation