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REG711-5: What will happen if we keep driving REG711EA-5 down below 2.7V to 2V

Poh Kok Keng
Genius 5402 points
Part Number: REG711-5
Other Parts Discussed in Thread: REG710-5

Dear Sir/Madam,

With REG711EA-5/2K5, I understand the spec mentioned Vin(min) is 2.7V to have REG711EA-5 regulated to 5V.

Can I check, what will happen if we keep driving REG711EA-5 down below 2.7V to 2V? Does the voltage output doubled? I understand it will not be regulated to 5V anymore.

Any test data to share?

Best Regards,

kpk

  • 0
    TI__Mastermind 21565 points

    Hi KPK:

    For the 5V version, we only recommend Vin larger than 2,7V. We won't expect it regulate Vout=5V anymore. 

    How about use a boost converter? 

  • 0 in reply to Minqiu Xie
    Genius 5402 points

    hi Minqiu,

    What will happen if we keep driving REG711EA-5 down below 2.7V to 2V? Does the voltage output doubled? I understand it will not be regulated to 5V anymore. Did TI have any data on this?

    Best regards,

    Kpk

  • 0 in reply to Poh Kok Keng
    TI__Mastermind 21565 points

    Hi Kpk:

    We don't have the data in hand. According to my analysis, the device can't regulate Vout=5V when Vin <2.5V. As there is no EVM in our  lab. It's hard to verify it.

    May I know the purpose for such question? If you still need 5V regulated with such low Vin, REG711 is not a good choice. And I recommend boost converter to you. 

  • 0 in reply to Minqiu Xie
    Intellectual 300 points

    Halo Minqiu,

    Thanks for the reply. The reason we asked that is because the end device is just 2 indicator LEDs. Hence it doesnt need to be strictly regulated as long as above Vf, the end customer is okay if the brightness vary a little bit when voltage not regulated from 5V to 4.xV.

    Since this charge pump is a regulated doubler, can I say that if Vin drop to 2.7V, the Vout is no more regulated, BUT it can still function and act as doubler?

  • 0 in reply to Handi Kartadihardja
    TI__Mastermind 21565 points

    Hi Handi:

    As there is little data in my hand, and no EVM to verify, I hard to explain the behavior under such condition.

    I have done a test based on REG710-5, which is similar to REG711. It could generator the Vout around double Vin when Vin is 2V-2.5V.

    But after all, please remind it's not a recommend usage. 

  • 0 in reply to Minqiu Xie
    TI__Mastermind 21565 points

    Hi Handi:

    As long time no hear from you, I assume you have solved the issue. If not, just reply below. Thank you!