ESP32 WROOM voltage sensitivity!!!

[FluxGS]

I have a design using the ESP32 WROOM 32D module and have found that a percentage of the devices are Supply Voltage sensitive for operation.

This is tested design with tested code and 3000 units in the field.

On the newest revision, I removed the voltage regulator since my operation is 3.6v battery operational.

What I observe for a percentage of the Modules is operational cutout at about VDD = 3.4 V and greater.

Using an adjustable power supply, the units program and operate at 3.3V no problem.

As the voltage increases, the units begin to have operational faults and reboot.

At about 3.6v the units do nothing when power is applied and draw no current; like the power pin was disconnected.

Is this a protection scheme within the Module?

I am operating from a 3.6v battery, directly to the Vdd.

Out of 1000 units built, about 30 exhibit this voltage sensitivity.