I have this project in which the life of the battery is imperative, after various designs i came up with this one: As you can see the pushbutton labeled START puts the CH_PD pin on HIGH for a brief moment, the module turns on, the GPIO2 set as an output latchs the module ON util it's time to turn it OFF again. Everything works fine, the thing is that when the module is on off state (CH_PD at LOW), the documentation says that the current drawn should be ~0.5uA which would be a blessing if that would be the case. On its off state this circuit is drawning 2mA from the power supply (that is way too much). Of course i don't expect to see a current drain of 0.5uA, but i do expect not more than 100uA. I fail to see why is this much current is flowing or where. Can you please help me?
Those SW are actually simple push buttons, i just didn't find 'em on Eagle.
- Yes, I'm using TXD and RXD as GPIO.
- When the SET button and the start button are pressed at the same time, the module boots on "SET SSID" mode. it's not really relevant to the question.
- I placed the Anode of the Green led towards VCC because if i set this led exactly as the RED one, for some reason it remains slightly on. It seems that when the CH_PD pin is in LOW the GPIO0 is on 3.3V, but with very low current capacity.
- The resistor next to RESET drawns 1.7nA.
- If i disconnect VCC from the ESP8266, the current drawn is 5uA (More than fine).
- In its OFF state, the voltage at each pin (without disconnect anything) is:
- GND 0.000 V
- GPIO2 1.461 V
- GPIO0 3.272 V
- RXD 0.002 V
- TXD 0.010 V
- CH_PD 1.465 V
- RST 3.274 V
- VCC 3.276 V
- The Multimeter i'm using is the FLUKE 8060a.
- Of course, i removed the internal LED of the module.
UPDATE: As @dandavis said the ESP8266-01S doesn't need to pull-up the CH_PD pin. As with my external pull-down resistor of 10K there vas a 1.465 V at CH_PD i calculated that this internal pull-up resistor was about 11.7 K. I looked for it and luckily found it. It was a SMD resistor of 11.9 K.
After removing it the current drawn at the OFF state is now 1.03 mA (less than half than before). Following this lead i bet there is internal pull-up resistors for GPIO0 and GPIO2. Thanks.