SPI Driver Selection

Daniel De Sousa

Other Parts Discussed in Thread: TXU0104, TXU0204, TXU0304, TXB0104, TXB0104-Q1, TXS0102, TXS0104E, SN74LXC2T45, SN74AUP3G34, SN74LVC3G34, SN74AXC4T774-Q1, SN74AXC4T245-Q1, SN74AXC4T774, SN74AXCH4T245, SN74LV4T125, SN74AVC4T245-Q1, SN74AVCH4T245-EP, SN74AVC4T774, SN74AXC4T245, SN74AVC4T245, SN74AVCH4T245, LMK1C1104, SN74AUC125, SN74AUC126, SN74LVC125A, SN74LVC126A, SN74AUP3G17

Hi there, we are looking for a 2-4 bit level shifter from TI to shift between 1V8/3V3 to 5V0. SPI_CLK and SPI_MOSI will be routed through this driver and will go to a relatively long LED strip. The intention is to run the interface at 4 MHz.

We are looking at the following devices for this application:
TXU0104
TXU0204
TXU0304
TXB0104 / TXB0104-Q1
TXS0102
TXS0104E

We have the following questions:
- are any of the devices above not recommended for this application? ie. drive strength, speed

- what is the major difference between the TXB and TXU line? We are familiar with the TSX and TXB drivers.

- besides the different number of bits, how are TXS0102 and TXS0104E different? What does the E represent?

Thanks in advance

over 3 years ago

0 Dylan Hubbard over 3 years ago

TI__Mastermind 44765 points

Hey Daniel,

TXS and TXB don't have much drive strength and I would ultimately avoid using them for unidirectional signals. For this, I actually recommend our new SN74LXC2T45 which will provide a better solution size when working with 2 signals.

TXU is fixed direction, TXB is auto bi-directional. TXU is suited for interfaces with unidirectional signals.

The E represents added ESD protection to the B port, functionality is the same.

0 Daniel De Sousa over 3 years ago in reply to Dylan Hubbard

Intellectual 580 points

Understood. The SN74LXC2T45 is not out yet in the package we want.

Would the TXU0304 be a good fit for this application?

0 Dylan Hubbard over 3 years ago in reply to Daniel De Sousa

TI__Mastermind 44765 points

Hey Daniel,

Since both of the signals you are working with go in the same direction, you could technically use any of the 3 variations (TXU0104, TXU0204, TXU0304). They offer different direction configurations, which you can find compared in the data sheets (section 5 of each one). I would see if there are any other signals you think may need translating or even just buffering to see how you want to utilize those extra channels (or just leave them unconnected, this will be fine as well).

0 Daniel De Sousa over 3 years ago in reply to Dylan Hubbard

Intellectual 580 points

Thanks!

Would the TXU0304 also be a good fit for the following application?
Clock splitter - 24 MHz 1.8V clock
1:3

0 Dylan Hubbard over 3 years ago in reply to Daniel De Sousa

TI__Mastermind 44765 points

Hey Daniel,

Are you also translating that to 5 V?

The signal split works for the TXU0304 configuration as it has 3 channels in one direction and 1 channel in the opposite direction.

0 Daniel De Sousa over 3 years ago in reply to Dylan Hubbard

Intellectual 580 points

The driver would act only as a splitter.
VCCA = 1.8V
VCCB = 1.8V

Is this a good use case?

0 Dylan Hubbard over 3 years ago in reply to Daniel De Sousa

TI__Mastermind 44765 points

Hey Daniel,

I guess I'm little confused by what you mean when you say splitter. Can you provide a quick block diagram of what you are trying to do?

0 Clemens Ladisch over 3 years ago in reply to Daniel De Sousa

Guru 283290 points

That would work. But a plain buffer like the SN74AUP3G34 or SN74LVC3G34 would be simpler and cheaper.

0 Daniel De Sousa over 3 years ago in reply to Clemens Ladisch

Intellectual 580 points

We are trying to use it since we are already using it for our SPI application. Less BOM lines for our application.

See application below:

0 Dylan Hubbard over 3 years ago in reply to Daniel De Sousa

TI__Mastermind 44765 points

Hey Daniel,

Okay I'm following now. The TXU device may struggle to meet that frequency. I would recommend the buffer suggestions made by Clemens. Unfortunately, it does mean more BOM lines, but you will likely save some cost and size.

0 Daniel De Sousa over 3 years ago in reply to Dylan Hubbard

Intellectual 580 points

Why would the TXU struggle? It mentions 200 Mbps in the datasheet.

0 Dylan Hubbard over 3 years ago in reply to Daniel De Sousa

TI__Mastermind 44765 points

Hey Daniel,

200 Mbps is for Max supply voltage which is best case, you are operating at 1.8 V near the minimum supply which will reduce the data rate. You can refer to section 7.6 for more info.

0 Daniel De Sousa over 3 years ago in reply to Dylan Hubbard

Intellectual 580 points

Understood. Good catch.

We have chosen the TXU0304 for the level shifter.

Would sticking with another voltage translator for the clock buffer application mentioned above still be okay? Something within the following list:

SN74AXC4T774-Q1
SN74AXC4T245-Q1
SN74AXC4T774
SN74AXCH4T245
SN74LV4T125
SN74AVC4T245-Q1
SN74AVCH4T245-EP
SN74AVC4T774
SN74AXC4T245
SN74AVC4T245
SN74AVCH4T245

0 Dylan Hubbard over 3 years ago in reply to Daniel De Sousa

TI__Mastermind 44765 points

Hey Daniel,

Yes, I would stick with the AXC devices. They will be the fastest in that list.

0 Daniel De Sousa over 3 years ago in reply to Dylan Hubbard

Intellectual 580 points

Understood. Final question.

For this application, would the LMK1C1104 be the best fit considering it is designed as a clock fanout chip?

0 Daniel De Sousa over 3 years ago in reply to Daniel De Sousa

Intellectual 580 points

In total we are considering the following:

Voltage translators & level shifters
SN74AXC4T774-Q1
SN74AXC4T245-Q1
SN74AXC4T774
SN74AXCH4T245
SN74LV4T125
SN74AVC4T245-Q1
SN74AVCH4T245-EP
SN74AVC4T774
SN74AXC4T245
SN74AVC4T245
SN74AVCH4T245

Buffers, drivers & transceivers
SN74AUC125
SN74AUC126
SN74LVC125A
SN74LVC126A
SN74AUP3G17
SN74AUP3G34

Clock buffers
LMK1C1104

0 Emrys Maier over 3 years ago in reply to Daniel De Sousa

TI__Guru* 96862 points

Hey Daniel,

For questions on new devices, I would recommend posting a new thread. This will automatically route the question to the correct team -- we don't support the LMK... parts.

0 Daniel De Sousa over 3 years ago in reply to Emrys Maier

Intellectual 580 points

No problem. Thanks for your help thus far

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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SPI Driver Selection