Author Topic: SI2306 - MOSFET  (Read 1460 times)

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Offline Nikos A.Topic starter

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SI2306 - MOSFET
« on: December 22, 2019, 03:04:30 pm »
Hi guys,

I want to use an n-channel to drive a buzzer (both datasheets are provided below). I supply Vgs=5V and the same voltage is supplied for the buzzer. The problem is that the buzzer does not activated.. From the power supply, it's shown that the current drawn is 10mA (not enough to drive the buzzer), it's like the FET cannot provide more current but I do know the reason... I measured the Rds ON to be sure that the gate is ON for positive Vgs and everything was ok. I am not sure i something is going wrong with the Vgs and Vds but looking the curves I couldn't find something. Thanks in advance

https://eu.mouser.com/datasheet/2/427/73234-241319.pdf

https://eu.mouser.com/datasheet/2/670/cmi-9705-0580-smt-tr-1627912.pdf

This is the test circuit


 

Online Siwastaja

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Re: SI2306 - MOSFET
« Reply #1 on: December 22, 2019, 03:14:52 pm »
Measure the voltage across the buzzer with a multimeter to verify the power supply, MOSFET operation and wiring in one go.

Test if the buzzer works by directly connecting to the 5V supply.
 

Offline Nikos A.Topic starter

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Re: SI2306 - MOSFET
« Reply #2 on: December 22, 2019, 03:43:58 pm »
I am a super idiot... I didn't thought that the buzzer has polarity and the datasheet otherwise the mitered corner, mention nothing about polarity...  |O
It works fine now, thanks!!
 

Online Siwastaja

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Re: SI2306 - MOSFET
« Reply #3 on: December 22, 2019, 09:31:12 pm »
Glad you found the issue - not all similar buzzers are sensitive to polarity, some work just fine either way.

Though, the datasheet does have it multiple times: (+) and (-), and "POLARITY PAD(+)", "POLARITY PAD(-)".
 

Offline Nikos A.Topic starter

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Re: SI2306 - MOSFET
« Reply #4 on: December 23, 2019, 05:16:21 am »
I didn't notice :( I have to be more carefull. Thank you for your assistance :)
 

Online Zero999

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Re: SI2306 - MOSFET
« Reply #5 on: December 23, 2019, 08:29:11 am »
Glad you found the issue - not all similar buzzers are sensitive to polarity, some work just fine either way.

Though, the datasheet does have it multiple times: (+) and (-), and "POLARITY PAD(+)", "POLARITY PAD(-)".
Yes, the old electromechanical buzzers which use an oscillator made from a relay with a normally closed contact in series with he coil are polarity insensitive, but the newer type which have a transistor oscillator are.

Another thing to note is the electromechanical buzzers require a freewheeling diode, because they generate back-EMF when the current in the coil is interrupred whilst the transistor type do not, as they have one built-in.
 

Offline Nikos A.Topic starter

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Re: SI2306 - MOSFET
« Reply #6 on: December 29, 2019, 02:07:15 pm »
Another thing to note is the electromechanical buzzers require a freewheeling diode, because they generate back-EMF when the current in the coil is interrupted whilst the transistor type do not, as they have one built-in.

Yes, you're right, I didn't even know about the coil inside... Thanks for the recommendations guys!!
 


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