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Intelligent Power Modules (IPM) Forum Discussions

mgurunathan
Level 1
Level 1
5 sign-ins First solution authored First reply posted

Hello,

 

I am interested in using IRSM808-204MH in a new product design.  The datasheet is not clear about a few things.

 

1.   How is the "DT" (dead time) pin supposed to be used?  What do you connect it to, and how does that control the dead-time?

2.   Is the part fully protected from a Shoot Through condition?  The truth table shows "Shoot Through" but does not explain if the part is protected from damage in this condition.

3.  What is the maximum switching frequency of this part?

Please advise, thanks.

Mohan

 

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1 Solution

Hi,

Sorry for late reply. Since, Vcc is logic power supply as well so if you operate at voltage less than prescribed in data sheet, the normal operating performance and functioning  will not be guaranteed.

Hence, the absolute lowest acceptable operating voltage for Vcc pin should be as per data sheet only.

BR,

AZIZ HASSAN

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6 Replies
AZIZ_HASSAN
Moderator
Moderator
Moderator
25 likes received 100 sign-ins 50 solutions authored

Hi,

Thank you for posting at Infineon community.

We apologize that the data sheet could not clear your points but I would like to clear it for you.

1) DT pin is used to set a dead time externally as per your requirement. The minimum dead time which is set in IPM is 0.9 usec. however, if you want more dead time you can set it externally by connecting a high value of resistor between DT pin and COM pin (ground or return path).

Internally, the DT pin controls the edge transitions between low side and high side input signals. To be precise, the DT pins controls the leading edge of the driver signal and hence provides the necessary delay between top and bottom switch. 

2) There is no internal shoot through protection. The logic table shown in data sheet depicts one of the input condition (Hin=1,Lin=0) which will lead to shoot through. This input shoot through can be protected by giving a delay between high and low side drive signal which is nothing but Dead time control. But if the shoot through happens due to some  other reason (example- zero impedance dead short circuit on switch output side ), then you need to provide a sense or feedback signal (through a sense resister )to your external controller IC. The connection diagram for your reference has been shown in data sheet on page number 6. I have attached the image for the same. 

AZIZ_HASSAN_1-1650086467363.png

3) Since, internally the switches are trench MOSFET with low Rds(on) , it can be used for high switching frequency applications. Please let me know your frequency requirement to confirm .

I hope you understood.

BR,

AZIZ HASSAN

 

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Hello Aziz,

 

Thank you for the clear response.  I understand now that there is no internal shoot through protection.

 

Regarding the DT pin:  you wrote that if I want to increase the dead time, I can add a resistor from DT to COM.  I do not know what value resistor to choose for a given dead time.   What is the relationship between resistor value and dead time?  

 

Thank you,

Mohan

 

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Hi,

Please refer to the graph attached which gives you a resistane value to be used as per different DT.

b622fc0b-86a9-46f6-8201-85a0c20f2e38.PNG

I hope this will serve your purpose.

BR,

AZIZ HASSAN

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mgurunathan
Level 1
Level 1
5 sign-ins First solution authored First reply posted

Thank you Aziz!

I have another question on this part.  There is a pin, VCC.  Datasheet recommends that VCC voltage be between 13.5V and 16.5V.   Is it possible to operate with VCC=12V?  Will the chip work properly with VCC=12V?

Please let me know absolute lowest acceptable operating voltage for VCC.

 

Thanks,

Mohan

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Hi,

Sorry for late reply. Since, Vcc is logic power supply as well so if you operate at voltage less than prescribed in data sheet, the normal operating performance and functioning  will not be guaranteed.

Hence, the absolute lowest acceptable operating voltage for Vcc pin should be as per data sheet only.

BR,

AZIZ HASSAN

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OK.  Thank you for the reply.

 

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