Every byte an SSD reads or writes crosses a narrow bus between the controller and the NAND dies. Two standards define that bus. The Open NAND Flash Interface (ONFI) dates its first specification to December 28, 2006, and Toggle DDR is the other family. Both have climbed from a few hundred megatransfers per second per pin into the thousands.
How fast the NAND bus got
The bus matters because a die can sense a page faster than an old bus could move it out. Samsung lists Toggle DDR at 133MT/s per pin in version 1.0, then 400, 800, 1,200 and 2,400MT/s through version 5.0. ONFI’s NV-DDR3 mode reached 1,200MT/s in ONFI 4.1 in December 2017 and 1,600MT/s in ONFI 4.2.
How fast the NAND bus got
The NAND bus went from 133 to 4,800MT/s per pin
The bars put both families on one scale. Toggle reached 3,200MT/s with Toggle 5.1 in Samsung’s ninth-generation V-NAND, and Kioxia and Sandisk showed a 4.8Gb/s interface on Toggle DDR6.0 at ISSCC 2025.
A faster bus lets more dies share one channel before the bus becomes the limit. Part 5 covers ONFI and Toggle and why the bus had to keep getting faster.
7 facts filed under NAND interface: 5 read in the original source and 2 reported by a second source. Each was checked against the source’s own words, so its figures appear there, and each names where it comes from.
Primary sources
ONFI 1.0 spec is dated Dec. 28, 2006 on the ONFI specs page.
ONFI 4.1 (December 2017) extends NV-DDR3 I/O speeds to 1066 MT/s and 1200MT/s.
ONFI 4.2 extends NV-DDR3 I/O speeds to 1333MT/s, 1466MT/s and 1600MT/s.
Samsung 8th-gen V-NAND release editor’s note lists Toggle DDR interface generations 1.0 (133Mbps), 2.0 (400Mbps), 3.0 (800Mbps), 4.0 (1,200Mbps), 5.0 (2,400Mbps).
Kioxia and Sandisk ISSCC 2025 3D flash reaches a 4.8Gb/s NAND interface using Toggle DDR6.0.
Secondary sources
Samsung 8th-generation V-NAND release editor note lists Toggle DDR 5.0 at 2,400Mbps per pin.
Samsung 9th-generation V-NAND uses Toggle 5.1, up to 3.2 gigabits-per-second per pin.
Sources
Primary is the original paper, standard or datasheet. Secondary is a review, a vendor summary or a news report. Measured is my own test data.
Show all 4 sources, 3 primary
- PrimaryONFI specificationsONFI
- PrimarySamsung begins mass production of 8th-gen V-NAND, Toggle DDR 5.0 editor noteSamsung, 2022
- SecondarySamsung begins industry first mass production of 9th-gen V-NAND, Toggle 5.1Samsung, 2024
- PrimaryKioxia and Sandisk ISSCC press releaseKioxia, 2025