Supply Voltage Dropping to 1.5V on Start. Somehow related to EN pin
Posted: Thu Mar 10, 2022 6:24 pm
Hello,
i have a really strange problem with our custom ESP32-Wroom board.
We are using a ISL9122AIINZ-T DCDC converter to generate the 3.3V from our battery. (I2C of the ISL is pulled up to VCC as in the datasheet)
The DCDC converter alone works fine ( we have 2 separate boards, the ESP is on the second one) i tried to put some load on it and it went on working fine up to 100mA.
But as soon as I Attach the ESP-Board, the voltage from the DCDC converter drops down to 1.5V. There is no short circuit as my power supply does not show any current ( >1mA) flowing. As soon as i detach the ESP-Board the supply goes back to 3.3V
Now the really strange part: when i pull the EN-Pin of the ESP down for just a moment (touch the pin with a cable connected to mass) the power supply jumps on the right 3.3V.
Once there the board work as intended.
If I switch on and off the power supply, or disconnect and reconnect the LCM board, the DCDC converter goes back to 1.5V.
We "solved" the problem by changing the RC-Circuit on the EN pin from10k/100nF to 100k/1uF which makes it start 100 times slower then given in the ESP-Reference.
I really have no clue, how the EN-Pin can impact the supply voltage whiteout generating some sort of short circuit.
I already excluded every other possibility on out boards by removing all components except the DCDC converter and the ESP32 from our boards.
Any help is appreciated
Edit:
clarity
i have a really strange problem with our custom ESP32-Wroom board.
We are using a ISL9122AIINZ-T DCDC converter to generate the 3.3V from our battery. (I2C of the ISL is pulled up to VCC as in the datasheet)
The DCDC converter alone works fine ( we have 2 separate boards, the ESP is on the second one) i tried to put some load on it and it went on working fine up to 100mA.
But as soon as I Attach the ESP-Board, the voltage from the DCDC converter drops down to 1.5V. There is no short circuit as my power supply does not show any current ( >1mA) flowing. As soon as i detach the ESP-Board the supply goes back to 3.3V
Now the really strange part: when i pull the EN-Pin of the ESP down for just a moment (touch the pin with a cable connected to mass) the power supply jumps on the right 3.3V.
Once there the board work as intended.
If I switch on and off the power supply, or disconnect and reconnect the LCM board, the DCDC converter goes back to 1.5V.
We "solved" the problem by changing the RC-Circuit on the EN pin from10k/100nF to 100k/1uF which makes it start 100 times slower then given in the ESP-Reference.
I really have no clue, how the EN-Pin can impact the supply voltage whiteout generating some sort of short circuit.
I already excluded every other possibility on out boards by removing all components except the DCDC converter and the ESP32 from our boards.
Any help is appreciated
Edit:
clarity