ONFI goes 3.0, introduces NV-DDR2 interface

Ups speeds, lowers cost

The Open Nand Flash Interface Working Group might not be one of the most prominent specification promoters in the business, but there’s a slow move towards using NAND Flash with ONFI interface in the industry, especially in SSDs. Today version 3.0 of the ONFI standard was announced and this is likely to bring a lot more supporters on board than previous iterations of the standard as it promises to bring increased performance and/or cost savings to the SSD makers.

One of the hurdles when making a SSD, is that to meet certain performance figures you need to add a set number of NAND Flash chips or you won’t be able to get to such performance figures. The reason for this is that the performance is based both on the individual performance of each NAND Flash chip and  the cumulative performance of all of the chips inside an SSD. What ONFI 3.0 brings to the table is a new non-volatile DDR2 interface which promises speeds of up to 400MB/s for each individual NAND Flash chip. This is a serious game changer in the industry as a whole.

There are two ways for a SSD maker to take advantage of the increased performance and the most obvious one is increased overall SSD performance. However, the second option is equally interesting, as half as many NAND Flash chips with an ONFI 3.0 interface can be used in an SSD while offering the same or potentially better performance than that of a current SSD.  This does require support from the SSD controllers and that’s not going to happen overnight.

In addition to the NV-DDR2 interface, ONFI 3.0 offers additional cost and space saving by utilizing fewer chip enable pins and controller pins which makes for simpler and smaller PCB designs. Although not supported in the current revision of the ONFI standard, we’ll also be seeing support for ECC Zero (EZ-NAND) interface in the future which will help simplify the SSD controllers by moving the error correction from the controller to the NAND Flash, a feature already supported in ONFI 2.3.

All the big NAND Flash makers have already expressed their support for the ONFI 3.0 specification and it looks like we can expect to see ONFI 3.0 based products from Micron, Intel, Phison, Spansion and SandForce if the press release is anything to go by. The bad news you ask? Well, SandForce doesn’t expect to have a controller ready until sometime next year and the other companies didn’t mention any time line on when they’d offer products with ONFI 3.0 support. That said, it takes time to implement new standards and at least we know we can look forward to faster SSD and other Flash memory based products by sometime next year.S|A

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