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

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? 

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

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. 

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?

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.