problem with 2EDF7275K when driving IMBF170R650M1

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IssacD
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5 replies posted 10 sign-ins First reply posted

The trigger singnal I used is  a typical TTL singnal (50us pulse width,50ohm output impedance, 5V) produced by a digital singnal generator.

TTL_singnal.jpg

I just directly connect the trigger singnal to both INA & INB.(in fact I only use channel A to drive a mosfet IMBF170R650M1. channel B is just for trigger feedback)

sheet.PNG

pcb.PNG

board.jpg

But when I used a probe to detect the singnal @ sma port, there was  another pulse (about 1ms

width) after about 200us .

detection@sma_port.jpg

 channel A output singnal and the mosfet behavior is agreed with the singnal above.

detection@channelA_output.jpg

 I dont understand how a single pulse trigger singnal create a much longer pulse followed when connected  to the driver IC 2EDF7275K.

 

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1 Solution
Akhil_B
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Hi @IssacD 

  1. "Please turn off the INA and INB signals"----- should I use the "disable" pin or  just disconnect the singnal generator with the board and check the output ?

           Disconnect the signal generator from the board and check the pulse at the output of the signal                            generator.

        2."Connec t the INA and INB signals independently"------Is it possible that the longer pulse                   followed is caused by some impedance dismatch when I connect the INA and INB together using a               Y branch route. Anyway I will check the singnal by connecting the INA and INB seperately.

        I suspect that the gate pulse you have shared in the above image is from the signal generator only. Once          the signal generator pulse is good, please connect the INA and INB signals separately and check.

 

 

Best Regards,

Akhil Kumar.

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5 Replies
Akhil_B
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Hi @IssacD 

Thanks for posting on the Infineon Community page.

Please turn off the INA and INB signals, then check the signal generator's output by giving the same pulse used in the previous test. Connect the INA and INB signals independently and test the signal whether it is good.

Are you using an evaluation board? Share the part number if yes.

 

Best Regards,

Akhil Kumar.

 

 

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IssacD
Level 1
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5 replies posted 10 sign-ins First reply posted

Thanks for your reply. This is not an evaluation board. It's just a board I use to test the function of the driver and the mosfet.

May I ask you some questions?

  1. "Please turn off the INA and INB signals"----- should I use the "disable" pin or  just disconnect the singnal generator with the board and check the output ?
  2. "Connect the INA and INB signals independently"------Is it possible that the longer pulse followed is caused by some impedance dismatch when I connect the INA and INB together using a Y branch route? Anyway I will check the singnal by connecting the INA and INB seperately.

 thanks for your reply again.

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Akhil_B
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250 sign-ins First question asked 50 solutions authored

Hi @IssacD 

  1. "Please turn off the INA and INB signals"----- should I use the "disable" pin or  just disconnect the singnal generator with the board and check the output ?

           Disconnect the signal generator from the board and check the pulse at the output of the signal                            generator.

        2."Connec t the INA and INB signals independently"------Is it possible that the longer pulse                   followed is caused by some impedance dismatch when I connect the INA and INB together using a               Y branch route. Anyway I will check the singnal by connecting the INA and INB seperately.

        I suspect that the gate pulse you have shared in the above image is from the signal generator only. Once          the signal generator pulse is good, please connect the INA and INB signals separately and check.

 

 

Best Regards,

Akhil Kumar.

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IssacD
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5 replies posted 10 sign-ins First reply posted

Hello Bandaru Akhil

Sorry for reply late. I stayed home for two weeks for the COVID-19 regulation.

I figured out what is wrong with the test today.

firstly, I checked the output of the singal generator with the 50 ohm input impedance of the oscilloscope. I got the correct 50 us pulse.

20221207191451.jpg

Secondly, I changed the input impedance of the oscilloscope to 1M ohm. Then I got the similar results with the ones when I connected the singnal generator to the board.

20221207191410.jpgHere is the result when I connect to the board.

20221207191341.jpgSo you are right that the problem is caused by the generator. The driver  2EDF7275K  must have a several hundreds kΩ pull-down resistor in the INA & INB, which makes the generator output a wrong wave. 

So I am going to connect both INA & INB with GNDI by a 100 Ohm resistor  in order to make the  input impedance of the driver to 50 Ohm.

Do you think it will work out?

 

 

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Akhil_B
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Hi @IssacD 

Please repeat the test by having the signal generator with 50 ohm termination.

 

Best Regards,

Akhil Kumar.

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