Serial ATA Bus

Serial ATA (Advanced Technology Attachment)


[SATA Description] [Serial ATA Jitter] [Interface ICs]
[SATA Connector/Cable] [SATA Pinout] [PATA]
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Serial ATA Description


The Serial ATA bus [SATA] is the serial version of the IDE [ATA] spec. SATA uses a 4 conductor cable with two differential pairs [Tx/Rx], plus an additional three grounds pins and a separate power connector. Data runs at 150MBps [1.5GHz] using 8B/10B encoding and 250mV signal swings, with a maximum bus length of 1 meter. Later SATA enhancements move the data transfer speed to; 300MBps [3.0Gbps], and then 600MBps [6.0Gbps]. The current speed for SATA is 600Mbps [6Gbps] for version 3.0 of the standard which was released at the end of 2009. Shielded external SATA [eSATA] data cable runs out to a maximum of between 3 feet and 6 feet. eSATA cables are used external to the chassis or case. Just released xSATA which is an external interface out to 8 meters.

SATA Protocol
The SATA Frame structure used between Host and Device is shown in the graphic below. The frame is made up of multi Dwords, which are in turn encapsulated by flow control and CRC information. The SATA frame begins with a Start-of-frame [SOF]. The SOF is followed by the Frame Information Structure [FIS]. Then the Cyclic Redundancy Code [CRC] is placed in the frame. The final block in the message is an End-of-Frame [EOF]. SATA uses a 32bit CRC [calculated over the contents of a (FIS) Frame Information Structure], stored as the 'Dword'.

The 32-bit CRC polynomial is X32+ X26+ X23+ X22+ X16+ X12+ X11+ X10+ X8+ X7+ X5+ X4+ X2+ X + 1.


SATA Message Frame
Serial ATA [SATA] Bus Protocol Frame

SATA Electrical
Serial ATA uses LVDS [EIA/TIA-644] with voltages of 250mV; while the obsolete parallel ATA interface is based on TTL signaling levels and rates. Serial ATA is a point-to-point interface where each device is directly connected to the host via a dedicated link. Because Serial ATA uses a dedicated link, adding another drive to the computer will have no impact on bandwidth. With Serial ATA the additional hard drive uses a separate SATA link, while the older IDE parallel standard [PATA] would see a degradation in speed because the drives would share the same link band width. The Bit Encoding used is: Non Return to Zero (NRZ) encoding for data communication on a differential two wire bus. The use of NRZ encoding ensures compact messages with a minimum number of transitions and high resilience to external disturbance. The termination resistor is 100 Ohms [+/- 5 Ohms] differential.

SATA Physical
Serial ATA uses only 4 signal pins, improving pin efficiency over the parallel ATA interface which uses 26 signal pins going between devices [over an 80 conductor ribbon cable onto a 40 pin header connector].
Serial ATA also provides the opportunity for devices to be 'hot-plugged', devices may be inserted or removed while the system is powered on. The pinout tables for Serial ATA are listed below.

The primary function of Serial ATA bus is to form an interface between the Motherboard and the Hard Disk Drive [HDD]. The Hard Drive may have a SATA connector and a legacy PATA data connector, with a legacy PATA power connector, so the device may function in either a legacy [older] motherboard or a currently produced motherboard. In this case the mother board S-ATA interface would be developed from a peripheral add-on board and not the motherboard. Power connectors on a HDD are header pins for a P-ATA interface and card-edge finger blades in the case of S-ATA. Some drive connectors shield the S-ATA power connector preventing their use, so you must use the P-ATA power pins to supply power to the drive. Terms used to describe the obsolete Harddrive interface which preceded the SATA interface include; IDE, Parallel ATA, PATA, and P-ATA.


Serial ATA Jitter Description

Deterministic Jitter [DJ], and Total Jitter [TJ] are listed in the table below. TJ is the addition of DJ and Random Jitter [RJ].
The Driver Output Jitter listed is the maximum allowed jitter from the driver. The Receiver Input jitter is the maximum jitter the receiver will tolerate.

SATA Jitter
Description Driver
Output
Driver PCB
Connector
Receiver PCB
Connector
Receiver
Input
DJ TJ DJ TJ DJ TJ DJ TJ
A0,p-p(UI) 0.15 0.33 0.175 0.355 0.25 0.43 0.275 0.455
n0
5
A1,p-p(UI) 0.2 0.45 0.22 0.47 0.35 0.6 0.37 0.62
n1
250
A2,p-p(UI)
40
n2
25000

The table does not account for UI error due to frequency skew. The final two rows list Total Jitter [TJ] only.





SATA Interface IC's

As with any interface, just because the latest revision of SATA runs at 6Gb/s
does not imply that a hard drive interface can sustain that speed.

Serial ATA uses LVDS [EIA/TIA-644] with voltages of 250mV.

Atmel {Serial ATA Bridge IC, PATA to SATA Converter}

Genesys logic {USB 3.0 to SATA 3Gb/s Bridge Controller, SATA to PATA Bridge Controller}

JMicron Technology Corporation {1 to 5-ports Serial ATA II Port Multiplier with RAID function support, PCI Express to SATA II Host Controller}

LSI Corporation {8-Port 3Gbps SATA Controller}

Marvell {Serial ATA Bridge IC, PATA to SATA Converter}

Mixel {Quad Gigabit Transceiver IP}

PLX Technology {FireWire/USB to SATA Controllers, USB to SATA Controllers, Consumer Network Attached Storage (NAS) SoC, Consumer Direct Attached Storage (DAS) SoC}

Silicon Storage Technology, Inc. 'SST' {SATA Disk Controller IC}

Soft Mixed Signal Corporation 'SMS' {SATA PHY transceiver IP}

Another listing of PC Chip Set Manufacturers, Programmable Logic IP Cores


SATA Standard Information

Serial ATA Revision 3.0, 5/2009
Serial ATA: High Speed Serialized AT Attachment; Revision 1.0, 1/2003
Serial ATA: High Speed Serialized AT Attachment; Revision 1a, 8/2001
Serial ATA: Electrical Specification; Revision 1.0, 5/2004
Serial ATA: Specification; Revision 2.6, 3/2007
SATA PHY Interface Specification [SAPIS] Intel
External Serial ATA [eSATA]

T13 {Technical Committee T13; AT Attachment} ...... Serial ATA {Serial ATA Working Group}


Serial ATA Pin Out

The Serial ATA bus is defined over two separate connectors, one for the data lines and one for the power lines. A Serial ATA Hard drive may also have a third connector for legacy PATA power connections. The PATA power connector may be used in instead of the SATA power to supply a connection which is more rugged and reliable then the SATA-1 power connection.

Some Solid State Drives [SSD] may not require all of the defined SATA power connections. In addition a Serial ATA Power Adapter Cable my be purchased to transitions from 15-pin SATA power to 4-pin Parallel power connectors [Backwards compatible for standard AT/ATX power supplies].

The pinout for SATA is listed on the SATA Pinout [Signal Assignments] page.





SATA Connectors and Cable Manufacturers

The cable uses two shielded pairs to carry data. The wire is 26 AWG solid copper wire. The impedance is 100 ohms. Common internal SATA cable lengths are 12, 18, and 36 inches. The internal cables maybe straight both ends or 90 degree. Shielded external SATA [eSATA] data cable run 3 feet or 6 feet. A Cable may also contain both SATA Data and Power combined into an 18inch cable. Illuminated cable is also available. For reference; the older IDE flat cable is five times wider then the new Serial ATA round cable. The smaller Serial ATA cable allows for better air flow within the Personal Computer chassis

Adam Technologies {SATA Connectors, Stacked SATA}

Amphenol {SATA Connector Manufacturer}

BAFO Technologies {SATA - 7 Pin Internal, 7 Pin External with Metal Shield, 15 Pin - 4 Pin Housing Power}

Belkin Corporation {Serial ATA Cable 18 inches, 24 inches, 3 foot length, Right Angled, Multi-Colored}

Circuit Assembly {Serial ATA Signal Cable}

DATACOMM Cables Inc {SATA 150, Straight 19"and 39 inch long. 90 degree bend 18" and 36 inch long}

Delphi {Serial ATA Cables}

FCI {SATA Connectors, SATA Cable Assemblies}

Foxconn {Serial ATA, 7/22 positions, SMT/Thru hole Single Row, RoHS}

Hitachi Cable Manchester, Inc. {Serial ATA 4-Conductor PVC Cable, 100 ohm differential Impedance}

Molex {Serial ATA Connectors and Cables Assemblies}

TaiSol Electronics {Serial ATA DIP Connectors, Serial ATA 15P/7P Male Female Connectors and Serial ATA Data Cable, Serial ATA Power Cable}

T-CONN Precision Corp. {SATA}

Tripp Lite {Serial ATA Signal Cable - 39" 7 Pin Straight Female/Female}

Tyco Electronics {Serial ATA 7 Position PCB MT Components, 7 Position Type I/type II Cable Assemblies, 26 AWG Bulk Cables}


Parallel ATA, IDE Description

PATA information is provided below for reference, how ever with the addition of SATA ~ PATA is now obsolete, you can refer to the Parallel ATA bus page for more information. Serial ATA uses 250mV switching levels instead of 5 volt TTL levels [reducing power requirements], a smaller cable [increasing air flow in the chassis], operates at 150MBps instead of 133MBps, and is Hot-Swappable.
Here is a chart of Hard Drive Transfer Speeds. The chart compares each version of PATA [ATA-1, ... ATA-7, and the 2 versions of SATA.

Serial ATA is not compatible with the IDE [Parallel ATA] because the connectors are different, the voltage levels are different, and SATA sends a bit at a time while PATA sends 16 bits at once. The two bus types will not interface with one another; PATA will not mate with SATA. The IDE bus will not connect to the SATA bus. Converter boards are available which translate Serial ATA to Parallel ATA interfaces for a cost around 50 dollars.

ATA-1 (IDE), [Obsolete] 8.3MBytes/sec, 8 or 16 bit data width, 40 pin data ribbon cable/connector. With a maximum of 2 devices on the bus. Using PIO Modes 0, 1 or 2. Performed no bus error correction.
ATA-2 (EIDE, or Fast ATA), [Obsolete] 16.6MBytes/sec, 8 or 16 bit data width, 40 pin data ribbon cable/connector. With a maximum of 4 devices on the bus. Using PIO Modes 0, 1, 2, 3, or 4
ATA-3, [Obsolete] 16MBytes/sec, 16 bit data width, 40 pin data ribbon cable/connector. Using PIO Modes 0, 1, 2, 3, or 4 and Multiword DMA modes 1 and 2. Runs with 120nS Strobes (rising edge to rising edge). Includes CRC.
ATA-4 Ultra-ATA/33, [Obsolete] 33MBytes/sec, 16 bit data width, 40 pin data ribbon cable/connector. Using PIO Modes 0, 1, 2, 3, or 4 and Multi-word DMA modes 1 and 2 and Ultra DMA modes 0, 1, and 2. Runs at a 60nS rate, using both edges of a 120nS Strobe.
ATA-5 Ultra-ATA/66, 66MBytes/sec, 16 bit data width 40-pin data connector/80 pin cable, with the additional 40 pins being Ground. Using PIO Modes 0, 1, 2, 3, or 4 and Multiword DMA modes 1 and 2 and Ultra DMA modes 0, 1, 2, 3 and 4. Runs at a 30nS rate, using both edges of a 60nS Strobe.
ATA-6 Ultra-ATA/100, 100MBytes/sec,16 bit data width 40 pin data connector/80 pin cable, with the additional 40 new pins being Ground. Using PIO Modes 0, 1, 2, 3, or 4 and Multiword DMA modes 1 and 2 and Ultra DMA modes 0, 1, 2, 3, 4 and 5.
ATA-7 Ultra-ATA/133, 133MBytes/sec,16 bit data width 40 pin data connector/80 pin cable, with the additional 40 new pins being Ground.


Topic Navigation: Engineering Home > Interface Buses > Personal Computer Buses > SATA Description.



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Modified 2/26/12
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