william mckinley asked 4 years ago
Currently converting a Remote Thermostat control from XBee and Arduino to ESPWroom02U using ESPNow. It drives SSR’s directly from the arduino outputs to control AC motors . It’s been working well for 3 years without failure. I need to drive them with the ESP. Max current draw for each SSR is 10ma, Normally the current is < 8 ma ea. There are three SSR’s and at times all 3 are enabled. I’ve found varying definitions of current capability of the ESP’s outputs and max current out values of concurrent multiple outputs. Must turn off voltage specification of the ssr’s is 1vdc, Min turn on voltage is 3vdc ,max voltage is 18vdc. Power supply for the entire module is currently spec’d for 3.3vdc.
I have 2 questions;
Do I need to buffer the ouputs to drive the SSR’s ?
Do I need to increase the board supply to 5vdc and then consequently regulate that to 3.3v for the ESP ?
Your Comments would be appreciated.
Steve Mercer answered 4 years ago
The nominal voltage of the ESP32 is 3.3V. There is no hard and fast rule regarding max current and it also depends on whether you are sourcing or sinking the current. Basically you can source up tp 40mA per pin and sink up to 28mA per pin (In general it’s recommended to keep those below 20mA) with a caveat that the sum of all the I/O current may not exceed 1200mA.
william mckinley answered 4 years ago
I’m using an ESPWroom02u which is a ESP8266. May consider going to an ESP32Wroom. But that’s to be decided down the road.
Thanks for the ESP32 info though
Sara Santos Staff answered 4 years ago
Hi.
For your specific board, you can check the datasheet here: https://www.espressif.com/sites/default/files/documentation/esp-wroom-02u_esp-wroom-02d_datasheet_en.pdf
It might provide more information.
Regards,
Sara
Steve Mercer answered 4 years ago
Apparently a whole lot of work went into the ESP32 power handling including doubling the pad sizes of pins. My understanding is the 8266 handles less than half of the 32.