CFast vs. SD Bus Interfaces
Comparing 2 standards across 13 specifications. 13 key differences identified.
CFast is a high-speed solid-state memory card standard developed by the CompactFlash Association (CFA) based on the Serial ATA (SATA) bus. Introduced with CFast 1.0 (SATA-II 3 Gbps) and refined in CFast 2.0 (SATA-III 6 Gbps), it delivers data throughput up to 550–600 MB/s in a rugged 24-pin form factor, widely adopted in professional cinema cameras (ARRI, Blackmagic, Canon).
SD Bus Interfaces define the physical and electrical signaling architectures through which SD and microSD cards transfer data with host controllers. Spanning legacy Default/High Speed, Ultra High Speed tiers (UHS-I up to 104 MB/s, UHS-II up to 312 MB/s, UHS-III up to 624 MB/s), and PCIe/NVMe-based SD Express (up to 3,940 MB/s).
Specification Comparison Table
13 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Body
|
CompactFlash Association (CFA) | — |
|
Physical Dimensions
|
36.4 mm × 42.8 mm × 3.6 mm | — |
|
Bus Interface / Protocol
|
Serial ATA (SATA 3.0 / 6 Gbps in CFast 2.0) | — |
|
Physical Connector Form Factor
|
24-pin keyed interface (7-pin SATA signal + 17-pin SATA power & control) | — |
|
Peak Data Throughput
|
Up to 550–600 MB/s (SATA-III physical ceiling) | — |
|
Nominal Operating Voltage
|
3.3V nominal | — |
|
Video Performance Guarantee
|
VPG-130 (130 MB/s minimum sustained write for 4K ProRes/RAW) | — |
|
Default Speed (DS) / High Speed (HS)
|
— | 12.5 MB/s (25 MHz @ 3.3V) / 25 MB/s (50 MHz @ 3.3V) |
|
UHS-I (SD 3.01)
|
— | SDR12 (12.5 MB/s), SDR25 (25 MB/s), SDR50 (50 MB/s), DDR50 (50 MB/s), SDR104 (104 MB/s @ 208 MHz 1.8V) |
|
UHS-II (SD 4.0)
|
— | 156 MB/s (Full Duplex) / 312 MB/s (Half Duplex) via 2nd pin row LVDS (0.26V) |
|
UHS-III (SD 6.0)
|
— | 312 MB/s (Full Duplex) / 624 MB/s (Full Duplex dual-lane LVDS) |
|
SD Express (SD 7.0 / 8.0)
|
— | 985 MB/s (PCIe 3.0 x1), 1970 MB/s (PCIe 4.0 x1 / 3.0 x2), up to 3940 MB/s (PCIe 4.0 x2) |
|
SD Express Protocol Stack
|
— | PCI Express (PCIe) + NVM Express (NVMe v1.3/1.4) over SD pins |