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why FDG901D (p mosfet driver) can not drive FDN360P mosfet

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EDA_hg81

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fdn360p schematic

I try using Sparan 3 to control FDG901D ( logic input is 3.3V CMOS) for driving FDN360P.

Why it did not work?

what it is the possible reasons for this?

Thanks
 

p mosfet driver

Can you show your schematic and describe which signals aren't working?
 

    E

    EDA_hg81

    Points: 2
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driver p-mosfet transistor

The whole idea is for realizing power on and power off sequence.

Use FDN360P as a switch by connecting the drain and source of FDN360P to transfer 12V DC from source to drain of FDN360P for enabling another power chip.

When I push a button, FPGA is going to set high ( 3.3V LVTTL) on the logic pin of FDG901D then FDG901D is going to turn on FDN360P by controlling the gate of FDN360P.

I have connected the VDD of FDG901D to 12 V and kept Slew pin floating.

The problem is when the whole system is powered on, the drain of FDN360p is already 12V even before I push the button.

What is the possible reasons?

Thanks in advance.

the following is the URL of the schematic:

https://obrazki.elektroda.pl/70_1183047159.jpg
 

p mos driver

If the MOSFET is 'ON' as you say it is then the gate of the device has enough voltage present to turn it on.

Have you looked at the turn on characteristics of the MOSFET you are using to see if these are compatible with the output of the driver as you have it configured. You may need to control the dv/dt of the driver instead of letting it float.

E
 

    E

    EDA_hg81

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Re: why FDG901D (p mosfet driver) can not drive FDN360P mos

I am really new to analog things.

I only checked Gate Threshold Voltage.

Would you let know which other Electrical Characteristics I should check?

Thanks.
 

Re: why FDG901D (p mosfet driver) can not drive FDN360P mos

Hi, for the FDG901D the max supply voltage is only 10V. In your schematic you are using 12V. Perhaps this is a mistake in your drawing or the chip is allready gone. Is there some reason why you are not using an ordinary transistor and some resistors? If it's a matter of space you might have a look at the resistor equiped transistors like the PDTC115ET. Also, for the FET, if you want to use an other type, be carefull. Some recent Fairch. FET's have a max. GS voltage of 7V. Exceeding this voltage can distroy your FET.


Regards
 

    E

    EDA_hg81

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As inventor(y) suggested, the 12V supply may have damaged the FDG901D by exceeding its absolute maximum VDD rating of 10V. See page 1 of the data sheet.

Assuming the chip survived, then maybe you are measuring 12V at the output simply because the output has no load, and the transistor has a small amount of leakage when "off". Try connecting a load, such as a 1K ohm resistor from drain to ground.

If that doesn't help, then what voltages do you measure at the transistor gate when the FPGA signal turns on and off?
 

    E

    EDA_hg81

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Re: why FDG901D (p mosfet driver) can not drive FDN360P mos

May be you are right.

I have noticed this, Since the power adapter I am using only can give me 12 V and I want to take chance.

thank your all suggestions.

I have to change it to 10 V to try again.

Have a good weekend.

Added after 1 hours 7 minutes:

I have tested this circuit using 10V input.

I also have found out that the Min Logic HIGH Input Voltage of FDG901D is 75% of VDD, this means the logic input is at least 7.5V.

I have used two power supplies to set two required voltages.

The followings are the results.

When logic input power is off:

the drain output of FDN360P is 10V
the gate voltage is 10V

When logic input power is on ( need 8 mS to be stable):

the drain output of FDN360P is 0V
the gate voltage is 0V

I did not find any requirement for logic input raising time.

Looks FDN360P is working but not correctly.

But any way 7.5 V input logic is not suitable for FPGA, can you help me to find a P channel MOSFET driver which can accept 3.3V logic and can tolerate 12V input power?

Thanks.
 

Re: why FDG901D (p mosfet driver) can not drive FDN360P mos

Hi, like I posted before. Take a look at resistor equipped transistors. For your circuit, an PDTC115ET will be fine. Below is a schematic. R23 is 220K. Note that the resistors inside the RET (PDTC114ET) in this circuit are not 100K + 100K like the PDTC115ET.

And indeed the max. supply rating of the FDG901 is 10V. But at 10V you will never reach logic high with a 3.3V drive. It is supposed to work between 2.7 and 6V.
 

    E

    EDA_hg81

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Re: why FDG901D (p mosfet driver) can not drive FDN360P mos

thank you so much for you help.

I am going to try next week.

have a nice weekend.
 

Re: why FDG901D (p mosfet driver) can not drive FDN360P mos

I found the replacement in digikey.
 

Re: why FDG901D (p mosfet driver) can not drive FDN360P mos

Hey inventor(y),

right now the circuit is working.


Thank you so much.
 

Re: why FDG901D (p mosfet driver) can not drive FDN360P mos

Nice to hear that.

Thanks
 

    E

    EDA_hg81

    Points: 2
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