17 November 2019

LDO HT7333 on ESP12F adapter plate

By Bolukan

On the back of the ESP8266 adapter plate a Low-dropout (LDO) regulator can be added to adapt a higher voltage to the needed 3.3V. If you add a LDO, the zero ohm resistor on the front side (middle resistor) needs to be removed.

I use a HT7333 which is more efficient than an AMS1117. Take notice the AMS1117 has a different pin configuration and cannot be used as replacement. The ESP8266 adapter plate is fitted with SOT-223 solder pads, but with some extra solder the smaller HT7333 SOT-89 fits nicely.

The HT7333 delivers a maximum of 250mA and its quiescent current is 3,5μA. The dropout voltage is less than 0,1V. This is less relevant as I use it to get down from 5V to 3.3V, but the HT7333 is very usable in combination with a LiPo batttery. With a less than 100mA typical use for an ESP8266, the 0,15 Watt heat production (1,7V x <0,1A) is not a problem.