High side switching with xiao esp32c6

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21

Hi Max

Yes that is correct. This would be a solution if you can tolerate the 0.7V drop when the voltage gets a bit lower. Keep in mind the 0.7V diode drop will be pretty constant over quite a wide range. Hence the use of diodes for this sort o application.
Cheers Bob

Also for your monitoring voltage divider. The values of 2k and 1k are a bit heavy on current, about 2.5mA. 20k and 10k would be a better combination and still produce the same result.

The reason for using low value resistors in a divider circuit is if the load (in this case I am assuming an ADC for voltage measurement) resistance is low enough it has to be considered as being in parallel with the lower divider resistor. In your case an ADC input resistance could be up into the GĪ© range so should not have any noticeable effect being in parallel with a resistor in the10s kĪ© range and I think could be safely ignored.
Things start to go astray when the lower divider resistor gets up into the MĪ© region when even trying to measure with a DMM (10MĪ© input resistance) will produce an error just by connecting the meter. So even measuring with a DMM (some people wrongly see such a measurement as Gospel just because it is digital) one has to be aware of instrument loading where high value resistances are involved. I might add that an oscilloscope on the 10X setting is the same 10MĪ© input resistance so the same applies.

22

Thanks, Iā€™ll look in to the use of a diode to reduce the voltage and Iā€™ll also change the values of the resistors.

23

Hi Max
The common 1N400X series diodes should do the job and are good for about 1A forward current.
Cheers Bob

24

This is the P-Channel mosfet I purchased, it had FQP27P06 as a label and is seen on the web page pic. Donā€™t know why the web page refers to it as IRF5305 and has that as a datasheet link.

A slightly more expensive one, donā€™t know which would be better.

regards
Jim

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25

Hi Jim
Interesting if you look at the pics. Both these devices are marked FQP27P06 but the data sheets are different.

Is this a Core thing with the pics or are both these items the same.

A bit confusing. So if you order the one that is supposed to be IRF5305 are you going to get that or a FQP27P06.
Cheers Bob
Probably in practice there would not be much difference anyway

26

Hi Mark,

This category on Digikey also offers some related devices: https://www.digikey.com/en/products/filter/power-management-pmic/power-distribution-switches-load-drivers/726

Liam

27

Hey Bob,

Often our product images are scraped from our supplier, this is likely a flow-on from their end. Iā€™ll look into changing these product pics for clarity.

28

Hi Zach
That would be good. Clear up a few conflicting thoughts. BUT, you should not have to do this. Your supplier should be a bit more up to date with their documentation. Change supplier would be one solution but that might be a bit drastic and not possible at this stage.
Cheers Bob

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