TIDA-00195: Desat Protection Question

Jamiryo

Part Number: TIDA-00195

Hi,

I have a question about desat protection of ISO5852 IC,

When I check the TIDA-00195 reference design, There is a schottky diode and zener diode in desat protection, Schottky diode clamps the DESAT input to GND2 potential at low-voltage levels.

What about zener there ? Can you explain the process clearly ?

Also can I put the zener diode with series to the desat protection diode for increasing the VCE(sat) protection level ?

Thank you

over 6 years ago

0 Jamiryo over 6 years ago

Intellectual 310 points

One more question,

I have 12 driver in my circuit as non-inverting configration. When fault occurs I want to stop all drivers. Cause of that I used that circuit as shown below;

When FLT signals are high, the DRV_FAULT will be grounded (ıts normal operation) . When fault occurs( FLT is low ) DRV_FAULT will be high. The DRV_FAULT port is going to the inverting inputs(IN-) of all drivers. Thus, drivers will stop, is it true right ?

0 Jamiryo over 6 years ago in reply to Jamiryo

Intellectual 310 points

do you have and idea ?

0 Navaneeth Narayanasamy over 6 years ago

TI__Intellectual 2890 points

Hello Aydin,
The answer for your first question - Zener at DESAT pin was added to suppress any high voltage which could damage the IC. This can happen if someone uses a DESAT diode with high capacitance. In practice this zener is not required provided right DESAT diode is used along with good layout. Since TIDA-00195 is an reference design, we have given provision for all possible use case.

For your second question: Yes, you can add zener diode in series with DESAT diode. This means you will trigger over current protection much earlier depending upon the value of zener diode.

regards
Navaneeth

0 Jamiryo over 6 years ago in reply to Navaneeth Narayanasamy

Intellectual 310 points

thank you for your answer, I will use SiC mosfet at high frequencies, such as 50-80 kHz, should I use SiC schottky diode as desat diode ?

Also, could you please answer the question at comment ?

0 Xiong Li over 6 years ago in reply to Jamiryo

TI__Intellectual 1665 points

Hi KAAN,

Fast recovery diodes usually work pretty well. SiC didoe may be preferred for applications with higher system voltage.

The DRV_FAULT circuit you proposed should work for its purpose.

With Regards,

Xiong

0 Jamiryo over 6 years ago in reply to Xiong Li

Intellectual 310 points

Thank you for your answer, I have one more question about gate driver buffer at schematic. Why did they use 4 SN74ALVC125PW ? Why some of channels of SN74ALVC125PW is empty ? For example in U3, why 2OE,3OE,4OE is empty ?

0 Xiong Li over 6 years ago in reply to Jamiryo

TI__Intellectual 1665 points

Hi KAAN,

There is no specific reason.

With Regards,

Xiong

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TIDA-00195: Desat Protection Question