SN65LV1023A analog and digital supply

Hi Fajar,

"DVCC and AVCC are separated internally and does not matter what the difference is for |DVCC−AVCC|, as long as both are within 3 V to 3.6 V"

From the word, i think it means we can use different voltage in DVCC and AVCC. For example, DVCC 3.6V and AVCC 3V is ok, because the two power supply are separated inside the chip, and they are both within the range of 3V to 3.6V. So if we just use the same source separated by beads, the interference between analog and digital supply should occurs. But in the EVM board schematic, it uses bead too. I need check more and tell you later.

Best Regards

Dylan

Hi Dylan,

Yes that's one thing I forgot to mention. I checked many of this kind of LVDS chips' datasheet and application notes and found that they utilize a combined ground and a source separated by beads only.

I think it is because it is not really "analog"; it is actually just the source for the digital circuit and the digital LVDS serial transmission circuit. Is it correct?

Best regards,

Fajar

Hi Fajar,

That's correct. Usually AVCC was supplied to PLL, receiver and transmitter analog module. In fact, this is an old part, there is no front end sampling and pre-emphisis module inside, and it would not be very sensitive to noise, so probably a bead is enough to filter the noise.

In other new parts, to get higher link performance, EQ, sampling, de-emphisis is included, we usually use separated power supply.

Best Regards

Dylan

Thank you for your thorough explanation, Dylan.

I am wondering is there any new parts that is as simple to interface as this one? The one without scrambling encoding etc.? It would be great if we can use something as simple as this but with higher performance

Fajar

Hi Fajar,

Please define your expectations for higher performance.

There are other devices that use this simple serialization scheme for larger payloads, such as the DS92LV16 or the DS92LV18.

For higher data rates, the devices will typically employ additional encoding. For example the DS92LV2421 or the DS92LV2422.

If you are looking just to extend the interconnect length, you could consider the DS15BA101 with the DS15EA101.

Mike Wolfe

DPS APPS / SVA

Hi Fajar,

The performance denpends on your application's requirements. SN65LV1023A is very easy to use, and is good enough for general usage.

If need some more functions, you can look into TLK2711-SP, it includes Pre-emphasis to extend cable length, 8b/10b decoding to get DC balance, comma detect and PRBS test pattern to do self test. what is your data rate, parralle width, and what kind of link and the length? There areother parts TLKxxxx, different data rate and different performace.

Best Regards

Dylan

Hi Dylan and Mike,

I am actually looking for more parallel pins but I want to use a 12MHz clock. From the suggestions, the DS92LV18 seems to be interesting although I need to check if I can increase the clock up to 16MHz.

Is there any other chip with more parallel pins than 10 but uses this simple scheme and can support 12MHz parallel clock? Actually I already tried to search but I couldn't find any.

Best regards,

Fajar

Hi Fajar,

The SN75LVDT1422 has 14 pins on its parallel interface and it can operate with a reference clock from 10-100MHz. I have some other recommendations with larger parallel interfaces but they require a minimum clock frequency of 20MHz, will that work for you?

Regards,

Michael Peffers

Analog Applications Engineer

Hi Fajar,

You could consider the DS99R103 and DS99R104. The encoding scheme uses the start stop bit architecture plus a simple DC balancing scheme that simply inverts the data bits if the overall disparity between ones and zeros is too high. This chipset is the pre cursor to our line of Channel/FPD-Link II type prodcuts that use more complex encoding.

Some nice features about the DS99R103 and DS99R104 are:

• 24-bit parallel bus
• the clock rate is 3 MHz to 40 MHz
• supports AC couple interconnects/cables
• no reference clock required
• progressive turn on for your LVCMOS outputs to reduce EMI
• transmit pre-emphasis to assist with signal integrity or extend cable reach

Mike Wolfe

DPS APPS / SVA