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Gate Driver ICs Forum Discussions

User21797
Level 2
10 questions asked 10 sign-ins 5 likes given
Level 2
Hi there,

We are using dev kit KIT_AURIX_TC234_MOTORCTR (https://www.infineon.com/cms/en/product/evaluation-boards/kit_aurix_tc234_motorctr/) and encounter a wired situation regarding SPI comm. with TLE9180.

For all the situations described bellow I did plugged in the power supply for the EMotor Drive board. So no power supply to TLE9180 can be ruled out.

If I only (without even starting debugger on computer) connect USB port to computer, sometime the voltage of MISO signal from TLE9180 will be lower than usual value (normal 5V, but now drop to 1V). The waveform is correct, only the magnitude of voltage is smaller. This result in MCU unable to read the return frame correctly. I have take some oscilloscope pictures here for your reference.

The situation disappear though if I unplugged the USB port and restart the board (power cycle). Only then I can plug in the USB port and start debugging without affecting TLE9180 SPI.

What's more if I hold the MCU in halt for too long same thing happened, as if something have discharged.

Thanks for reading, thanks in advance to any reply ^_^
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1 Solution
Abhilash_P
Moderator
Moderator 25 likes received 250 replies posted 250 sign-ins
Moderator
Hi,

The SPI interface has to be turned on only when the board is fully powered up. If not then the voltage drop in the SPI MISO pin is expected. Please refer the following snippet from the datasheet of TLE9180D that clearly mentions about the powering up,

5298.attach

I hope this explanation has made you understand the exact reason for lowered voltage on MISO pin.


Regards,
Abhilash P

View solution in original post

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4 Replies
Abhilash_P
Moderator
Moderator 25 likes received 250 replies posted 250 sign-ins
Moderator
Hi,

The SPI interface has to be turned on only when the board is fully powered up. If not then the voltage drop in the SPI MISO pin is expected. Please refer the following snippet from the datasheet of TLE9180D that clearly mentions about the powering up,

5298.attach

I hope this explanation has made you understand the exact reason for lowered voltage on MISO pin.


Regards,
Abhilash P
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User21797
Level 2
10 questions asked 10 sign-ins 5 likes given
Level 2
Hi Abhilash,

Thanks for the reply!!

Can elaborate more how to know if the board is fully power up? I have tried the following methods but all in vain:

1. wait for 10s before start reading from SPI
2. follow the power up sequence in TLE9180 datasheet (only the first few steps, please see attached picture for them)
3. provide higher voltage

5309.attach
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User21797
Level 2
10 questions asked 10 sign-ins 5 likes given
Level 2
Some update, I mange to somehow solve the problem but no idea why it work.

With more testing I found that just after initing TLE9180 the SPI actually work fine. But if I also init TLF35584 (turn off it's watchdog, like what AP32260 did only in main) the SPI will stop working right after.

A bit digging I found that the SPI register write sequence AP32260 have an error. When it turn on standby regulator it also writing a bit to TLF35584's reserved area. (more precisely when writing to register 0x04, the original program write 0b00010001, but bit 1 to 7 is reserved and should always write 0) SOMEHOW correcting this will solve the problem. No more low voltage at TLE9180 MISO pin.

But how this work? TLF35584 and TLE9180 are completely separate. No pin between them is connected. The only explanation I can think of is by writing to TLF35584 reserved register this somehow affect MCU's power supply (but not serious enough to restart MCU's program?) and somehow this make TLE9180 thought MCU is not fully power up? But I can't measure power supply to MCU, the line is hidden in circuit baord

Appreciate if anyone can shine some light on this problem 😄
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Abhilash_P
Moderator
Moderator 25 likes received 250 replies posted 250 sign-ins
Moderator
Hi,

The snippet from the datasheet didnot get uploaded in my previous reply. Please find below the snippet,

5327.attach


"But how this work? TLF35584 and TLE9180 are completely separate. No pin between them is connected."
Please find below the image that might answer your above question,

5328.attach


"But I can't measure power supply to MCU, the line is hidden in circuit baord"
Can you please confirm if the datasheet mentions whether the MCU must be powered up or the gate driver before staring the spi sequence.



Regards,
Abhilash P
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