Questions about Lattice MachXO - Page 1
Forum section: electronics / general

author: PartialDischarge
author_rank: Super Contributor
timestamp: March 10, 2020, 02:05:22 pm
content: I have some experience with smallers Lattice ispMACH 4000 devices programmed with ispLever, but now I need a MachXO for I need LVDS and prefer to avoid glue logic.1) I need to drive/read the LVDS signals of an ADC LTC2386 (CNV, CLK, DA...), so the smaller device to support this would be the MachXO1200 if I'm reading the datasheet correctly?2) Where in Lattice Diamond would I specify that these are LVDS outputs/inputs?

author: KrudyZ
author_rank: Frequent Contributor
timestamp: March 10, 2020, 03:26:29 pm
content: 2) There are three different methods to specify attributes, such as the IO type. It can be done in the HDL source, in spreadsheet view or in the preference file.This is all described in the Lattice technical note TN1280. This TN is for the MACHXO3, but I would imagine it would be the same for the MACHXO.What's your reason for wanting to use the older parts?

author: PartialDischarge
author_rank: Super Contributor
timestamp: March 10, 2020, 04:24:44 pm
content: Quote from: KrudyZ on March 10, 2020, 03:26:29 pmI just need the smallest (in mm2), cheapest FPGA to interface with a LVDS ADC and generate its clock (around 200MHz) plus a bit of logic inside. Is there a better option?

author: fourfathom
author_rank: Super Contributor
timestamp: March 10, 2020, 04:31:04 pm
content: You can do an "emulated" LVDS output on the smaller MachX02 parts (see figure 3-1 on the MachX02 Family Datasheet). I don't know if this is good enough for your ADC interface.I'm using the MachX02-1200 instead of the newer X03 parts because of the packaging. X03 are all BGA, and the low-count packages require a 1.2V core voltage. the X02 I'm using comes in a 32QFN package which is easier for me to prototype with, and it lets me run the whole chip on 3.3V. The performance of the X02 and X03 parts seems to be about the same. I've designed systems (about 20 years ago) that used 1000+ ball BGA parts, and I realize that the assy process has only become easier, but back then I had other engineers and layout people working for me, and we used outside assy services. These days I prototype in my garage and the designs are much simpler.

author: PartialDischarge
author_rank: Super Contributor
timestamp: March 10, 2020, 04:51:31 pm
content: Thanks because I had not noticed that the XO2 actually comes in smaller packages (32 pin) than the XO (100 pin tqfp), the emulated LVDS is also interesting...

author: KrudyZ
author_rank: Frequent Contributor
timestamp: March 11, 2020, 03:23:16 am
content: If you can live with 28 IO pins then the LCMXO3L-1300E-5UWG36C would be the smallest and cheapest part.2.49mm * 2.54 mm and $2 in 100 pcs from Digikey (cheaper elsewhere).The MACHXO3 have real LVDS on the top and bottom edge banks.

author: Cerebus
author_rank: Super Contributor
timestamp: March 13, 2020, 08:33:06 pm
content: Quote from: KrudyZ on March 10, 2020, 03:26:29 pmMachXO sysIO Usage Guide TN1091MachXO2 sysIO Usage Guide TN1202They are both very similar to TN1280. Other than finding how to specify device unique IO parameters they are otherwise almost interchangeable.