ESP8266 Community Forum

- Wed Oct 23, 2019 3:02 am #84286 Hi,

I have a project with ESP8266 which I want to power from single-cell LiPo battery, which means voltages from 4.2V to 3.5V (I won't go any lower, so the LiPo lasts longer). I need to use a linear regulator to bring down the voltage to 3.3V for the ESP. Problem is finding a LDO that can handle 500mA (ESP peaks up to 435mA I think), and has a voltage dropout less than 0.2V at that maximum current.
Several key points:

1. I cannot use boost converter to 5V and then the internal ESP linear regulator, because that would make the setup very power inefficient, and efficiency is paramount.
2. I cannot use a switching regulator either because of complicated reasons that are beyond the scope of this question. For simplicity's sake, let's just say it is off-limits for this project. I have to use an LDO.
3. I know ESP can work at lower voltages than 3.3V, but I need to use analog input to monitor the LiPo voltage and shut it off automatically when it discharges to prevent damage. If ESP receives less than 3.3V, the analog won't have a known reference voltage anymore, and it will be impossible to make reliable readings. So ESP must have 3.3V no matter what, meaning the LDO dropout cannot be larger than 0.2V.
4. To complicate things further, I live in the part of the world where it's extremely difficult, or expensive, to buy things online. Pretty much the only reasonable option is Ebay and Aliexpress, shipping from China. So I have to use whatever the Chinese produce.

I had moderate success with TCP 1700-3302E linear regulator, readily available from China, which has a dropout voltage of 0.178 V, but it can only provide 250mA. It is not enough to handle the current spike that happens when ESP8266 boots, and so I need big capacitors to take that spike, otherwise ESP will not boot. I suspect I will burn that 1700 soon enough, as it is not meant for such loads.

I found some LDOs that fit my requirements on websites like www.lcsc.com and www.digikey.com, but none of them are available from Ebay/Aliexpress, making them pretty much unobtainable in my country, unless I'd be willing to pay 10x for the shipping than I would pay for the component itself.

So, I am wondering if perhaps someone can suggest a 500mA, <0.2V dropout LDO that is available from Ebay or Aliexpress?

- Wed Oct 23, 2019 7:21 am #84290 You're not the only one.
Have a read through this very informative forum thread.

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Wed Oct 23, 2019 3:50 pm #84293 I use the xc6203E332 for LIPO LDO ESP8266 applications. This unit is easily obtainable on eBay at very good prices (especially in lots of 10). It has low quiescent current and low drop out.

The E variant does not have a hard current limiter and can supply pulse currents up to 600mA. The ESP8266 can have short duration current requirements of 300 - 400mA but the average current (~80mA) is much less so power dissipation and average current draw is not a problem.

- Wed Oct 23, 2019 4:47 pm #84294

You're not the only one.
Have a read through this very informative forum thread.

Thank you very much, that is a great list! AP2112 looks especially promising. I'll order a bunch of them from Ebay.

I use the xc6203E332 for LIPO LDO ESP8266 applications. This unit is easily obtainable on eBay at very good prices (especially in lots of 10). It has low quiescent current and low drop out.

The E variant does not have a hard current limiter and can supply pulse currents up to 600mA. The ESP8266 can have short duration current requirements of 300 - 400mA but the average current (~80mA) is much less so power dissipation and average current draw is not a problem.

Which XC6203E332PR are you using, exactly? When I searched for datasheet, I found FH, FL, FR, LB, and a dozen other variants...