At Computex 2023, Phison is introducing a new, lower-cost SSD controller for building mainstream PCIe 5.0 SSDs. The Phison PS5031-E31T is a quad channel, DRAM-less controller for solid-state drives that is designed to offer sequential read/write speeds up to 10,8 GB/s at drive capacities of up to 8 TB, which is in line with some of the fastest PCIe 5.0 SSDs available today.
The Phison E31T controller is, at a high level, the lower-cost counterpart to Phison's current high-end PCIe 5.0 SSD controller, the E26. The E31T is based around multiple Arm Cortex R5 cores for realtime operations, and in Phison designs these are traditionally accompanied by special-purpose accelerators that belong to the company's CoXProcessor package. The chip supports Phison's 7th Generation LDPC engine with RAID ECC and 4K code word to handle the latest and upcoming 3D TLC and 3D QLC types of 3D NAND. The controller also supports AES-256, TCG Opal, and TCG Pyrite security.
The SSD controller is organized in four NAND channels with 16 chip enable lines (CEs) each, allowing it to address 16 NAND dies per channel. For now Phison is refraining from disclosing NAND interface speeds the controller supports, though given the fact that the controller is set to support sequential read/write throughput of 10,800 MB/s over four channels, napkin math indicates they'll need to support transfer rates of at least 2700 MT/s. This is on the upper-end of current ONFi/Toggle standards, but still readily attained. For example, Kioxia's and Western Digital's latest 218-layer BICS 3D NAND devices support a 3200 MT/s interface speed (which provides a peak sequential read/write speed of 400 MB/s).
Phison says that its E31T controller will enable M.2-2280 SSDs with a PCIe 5.0 x4 interface and a capacities of up to 8 TB. Phison's DRAM-less controllers tend to remain in use in SSD designs for quite a while due to their mainstream posiitoning and relatively cheap price, so, unsurprisingly, Phison traditionally opts to plan for the long term with regards to capacity. 8 TB SSDs will eventually come down in price, even if they aren't here quite yet.
|Phison NVMe SSD Controller Comparison|
|Market Segment||Mainstream Consumer||High-End Consumer|
|CPU Cores||1x Cortex R5||1x Cortex R5||1x Cortex R5||2x Cortex R5||3x Cortex R5|
|Error Correction||7th Gen LDPC||5th Gen LDPC||4th Gen LDPC||5th Gen LDPC||4th Gen LDPC|
|Host Interface||PCIe 5.0 x4||PCIe 4.0 x4||PCIe 4.0 x4||PCIe 5.0 x4||PCIe 4.0 x4|
|NVMe Version||NVMe 2.0?||NVMe 2.0?||NVMe 1.4||NVMe 2.0||NVMe 1.4|
|NAND Channels, Interface Speed||4 ch,
|Max Capacity||8 TB||8 TB||4 TB||8 TB||8 TB|
|Sequential Read||10.8 GB/s||7.4 GB/s||5.0 GB/s||14 GB/s||7.4 GB/s|
|Sequential Write||10.8 GB/s||6.7 GB/s||4.5 GB/s||11.8 GB/s||7.0 GB/s|
|4KB Random Read IOPS||1500k||1200k||780k||1500k||1000k|
|4KB Random Write IOPS||1500k||1200k||800k||2000k||1000k|
Compared to the high-end E26 controller, the E31T supports fewer NAND channels and NAND dies overall, but enthusiasts will also want to take note of the manufacturing process Phison is using for the controller. Phison is scheduled to build the E31T on TSMC's 7nm process, which although is no longer-cutting edge, is a full generation ahead of the 12nm process used for the E26. So combined with the reduced complexity of the controller, this should bode well for cooler running and less power-hungry PCIe 5.0 SSDs.
The smaller, mainstream-focused chip should also allow for those PCIe 5.0 SSDs to be cheaper. Though, as always, it should be noted that Phison doesn't publicly talk about controller pricing, let alone control what their customers (SSD vendors) charge for their finished drives.
As for availability of drives based on Phison's new controller, as Phison has not yet announced an expected sampling date, you shouldn't expect to see E31T drives for a while. Phison typically announces new controllers fairly early in the SSD development process, so there's usually at least a several month gap before finished SSDs hit the market. Case in point: drives based on Phison's PCIe 4.0 E27T controller, which was announced at Computex 2022, are still not available. Otherwise, as Phison's second PCIe 5.0 controller, the E31T should hopefully encounter fewer teething issues than the initial E26, but we'd still expect E31T drives to be 2024 products.