Hi guys,
I have designed a zigbee fan controller using esp32h2. Initially it was working normally and after sometime when we tried to turn on the fan the chip was resetting. After working for sometime the board got heated and the IC got shorted . Can anyone explain why this happened?
thanks in advance.

 

Hi guys,
I have designed a zigbee fan controller using esp32h2. Initially it was working normally and after sometime when we tried to turn on the fan the chip was resetting. After working for sometime the board got heated and the IC got shorted . Can anyone explain why this happened?
thanks in advance.View attachment 323554View attachment 323554

You need resistor at the base of each transistors like 2.2k to limit the base current. 3.3v/2.2k should be ok

 

You need resistor at the base of each transistors like 2.2k to limit the base current. 3.3v/2.2k should be ok

How does that help in eradicating the brownout issues

 

How does that help in eradicating the brownout issues

Because it reduces the base current to a sensible amount. Without them, the current is only limited by the outputs of the IC.

 

Because it reduces the base current to a sensible amount. Without them, the current is only limited by the outputs of the IC.

I thought that brownout is caused due to excess current consumption by the fan during startup, causing the voltage to drop.

 

Hi aak,
What current is your 12V supply rated?
What is the load current of the Fan?
E

Update:
Clip from a fellow fan user.
My power supply is an old router power supply I found which provides max 200mA at 11.8V. My circuit uses 11mA without the fan so this is perfect!

However when the fan starts up it can draw anywhere between 180mA to 305mA!
Using my bench supply I have confirmed that the fan starts fine every time with anything about 28mA.

 

Hi aak,
What current is your 12V supply rated?
What is the load current of the Fan?
E

Update:
Clip from a fellow fan user.
My power supply is an old router power supply I found which provides max 200mA at 11.8V. My circuit uses 11mA without the fan so this is perfect!

However when the fan starts up it can draw anywhere between 180mA to 305mA!
Using my bench supply I have confirmed that the fan starts fine every time with anything about 28mA.

My power supply provides a current of 360mA and my fan may consume 320mA normally, but according to some information that I got that they may consume twice or thrice the rated current during the startup. I am using an esp32h2 chip which consumes 350mA.

 

hi aak,
I would say your PSU is underrated for the project, as you know the ESP32 has a high current draw.
This underrate would cause a brownout.

E

 

Thanks for

hi aak,
I would say your PSU is underrated for the project, as you know the ESP32 has a high current draw.
This underrate would cause a brownout.

E

the information ,but what might be the reason for the esp32 getting short.

 

what might be the reason for the esp32 getting short.

As stated in post #2 excessive current draw from output pins because you don't have any resistors between output pins and the bases of the transistors. That's a guess based on the information provided and not knowing exactly what "esp32 getting short" means. I assume it means the esp32 is dead and just gets hot when power is applied to it.

 

My power supply provides a current of 360mA and my fan may consume 320mA normally, but according to some information that I got that they may consume twice or thrice the rated current during the startup. I am using an esp32h2 chip which consumes 350mA.

Seriously, you cannot see the problem with that? 320mA + 350mA? Is that less than the 320mA rating of the supply?

 

My power supply provides a current of 360mA and my fan may consume 320mA normally, but according to some information that I got that they may consume twice or thrice the rated current during the startup. I am using an esp32h2 chip which consumes 350mA.

How are you powering the ESP32? Maybe you are using a 12 to 5V regulator and powering the ESP32 via its 5V pin. Do you have a schematic showing how your 12V power supply connects to the board shown in your opening post and how it connects to the ESP32?

 

How are you powering the ESP32? Maybe you are using a 12 to 5V regulator and powering the ESP32 via its 5V pin. Do you have a schematic showing how your 12V power supply connects to the board shown in your opening post and how it connects to the ESP32?

 

Have you looked at the ESP32 supply voltage with a scope? Does it actually show a brownout? Switching supplies are notoriously sensitive to PC board layout conditions. Looking at the output would definitely show if there's a problem with the regulator and would help to confirm voltage stability as the fan is turned on.