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Part Number: TXS0108E
I configed the MMC0 of AM3358 to SD Card interface but power supply is 1.8V to match other functional requirement, used the TXS0108E as voltage translator.
I think the data rate isn't the cause as TXS0108 can up to 60M in my application.
Is it because the Initialization and Identification between it and Host (AM3358) cannot pass? If yes, how can I modify the host driver?
Please help to advise, thanks!
The schematic as below
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The TXS has integrated pull-up resistors; you do not need the external ones.
The resistors R9/R22/R23/R24 create voltage dividers with the internal pullups; unused I/Os should be simply left open.
I notice that there is no pull-up resistor on the CLK line. Would the TXS's internal pullups be harmful?
Can you show oscilloscope traces of when the AM3358 tries to boot?
In reply to Clemens Ladisch:
Thanks for reply.
1. Yes, and I have tried to remove these external resistors(R4~R8, R11~R15), and the result was unchanged.
2. It will be implemented to next version and I did as your recommended in today's test(of course, it has no effect on the results).
3. No, I set it to 'DNP' based on SD Card Standard recommended.
4. Attached the oscilloscope traces and test log based on #1 and #2.
Only capture waveforms of the following frequencies, 50MHz waveform is strange as the fastest rate is 25MHz for SD Card.
log for SD Debug_20190819.txt
In reply to user6132308:
The schematic looks fine, the A7/ A8 and B7/ B8 can be left floating as the TXS has internal PUs and thus helps in conserving power.
From what i see from the scopeshots, the device is translating 1.8 <>3.3V. The waveforms for 1.8V has another corresponding 3.3V output. Is the CLK at 30Mbps or at 2Mbps?
Watch the Introduction to AXC Family
Read the app note on Glitch-free Power Sequencing for the AXC family
Evaluate the AXC8T245 EVM and watch the translation using the EVM
In reply to ShreyasRao:
Thanks for your guide, we captured the waveforms at high frequencies and found that the rise time and fall time of pulse were exceed.
The cause was I used unsuitable TVS Diodes(high parasitic capacitance) on CLK/CMD/DAT lines, and the functional passed after removed these Diodes.
Excellent, glad to know that it is working now.
I appreciate your feedback on the root cause and sharing it here ! Hopefully, it will be helpful to all the fellow engineers.
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