TXB0304 input drive

RSM55285

Other Parts Discussed in Thread: TXB0304, SN74AVC4T774

Hi,

We are using TXB0304 to interface a 3.0 SPI FLASH to a processor which has 1.8V SPI interface. We can recognise the FLASH and perform short read/erase/write cycles. When we are trying to perform erasing/writing large amounts of data we get issues. One of the things we notice in the datasheet for the TXB0304 is the drive requirements which needs to be +/- 3 mA. The CPU that we are using can sink 3mA but cannot source more than 1mA. Can this be an issue? When we check the waveforms on the scope - they look at the right level.

Any clues - pointers which might explain the behaviour. The FLASH device we are using is N25Q512 from Micron.

thanks

regards, Ranjeet

over 10 years ago

0 James Lockridge19 over 10 years ago

TI__Genius 14487 points

Ranjeet,

I am moving this question to the Voltage Translation forum for better support. In the meantime, it would help if you could provide us with the oscilloscope waveforms and a schematic of your application.

0 C. Ryan Land over 10 years ago

TI__Genius 9860 points

Moving to Translation forum for support.

-Ryan

0 RSM55285 over 10 years ago in reply to C. Ryan Land

Prodigy 160 points

I cannot seem to attach documents - can you advice and I can send across pdf of the schematics.

thanks

0 James Lockridge19 over 10 years ago in reply to RSM55285

TI__Genius 14487 points

When you go to reply to this post, click the link "Use rich formatting" below the bottom-right of the text box. It takes you to a new page with a text box and tool bar that gives you options for attaching files. I think you need to click on the one that looks like a picture to attach a pdf.

0 RSM55285 over 10 years ago in reply to James Lockridge19

Prodigy 160 points

Hi,

Please find the schematics attached. Please see the following notes which apply to the schematics:

Notes:
1. FARMI_SPI1 BUS is connected to the SPI bus of the CPU - the signals are 1.8V compliant.
2. The Voltage rail PWR_FLASH_2V75 has been increased to 3.0V
3. The control GPIO i.e. GPIO[8], GPIO[17] are all 1.8V compliant signals

I'll be shortly digitzing waveforms and sending it across. Are there specific points you wish me to probe?

thanks

0 RSM55285 over 10 years ago in reply to RSM55285

Prodigy 160 points

spi_flash.pdf

0 Wei Lang over 10 years ago

TI__Expert 6430 points

Hi Ranjeet,
If input driver is less than 3mA, the data rate will not achieve the spec parameter. If SPI flash SPI interface is jsut standard SPI interface ( not dual SPI or Quad SPI). Please use SN74AVC4T774 which can used in standard application and the its data rate is more than TXB0304's.
ThanksWei

0 RSM55285 over 10 years ago in reply to Wei Lang

Prodigy 160 points

Hi,

We are looking to wire in a SN74AVC4T774 - one issue we have is that the OE signal polarity is inverted for this device. We do have an invertor in board which is inverting the control signal but the voltage level is higher. So the question here is - is it possible to provide 3.0V compatible signal to drive OE\ when VCCA is 1.8V? The data sheet of the device does indicate that all I/O's are tolerant till 3.6V but does not explicitly state that it is possible to drive OE\ from 3.0V compliant signal when VCCA is connected to 1.8V.

Also - assuming we do have to drive a Quad Mode SPI device - can you recommend some other device besides TXB0304.

thanks

0 Wei Lang over 10 years ago in reply to RSM55285

TI__Expert 6430 points

Hi,

OE can be pulled up to 3V when VCCA=1.8V.

If application is Quad mode SPI, the optional translation device could be LSF0104.

Thanks

Logic

Logic forum

TXB0304 input drive