Serial ATA Bus

Serial ATA (Advanced Technology Attachment)

[SATA Description] [Interface ICs]
[SATA Connector/Cable] [SATA Pinout]

Serial ATA Description

The Serial ATA bus [SATA] is the new serial version of the IDE [ATA] specification. 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 300Mbps [3Gbps]. 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.

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 motherboard or a currently produced mother board. 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.

SATA Interface IC's

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

Genesys logic {Serial ATA Gen II 3.0Gbps PHY IP Core}

LSI Corporation {8-Port 3Gbps SATA Controller}

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

Mixel {Quad Gigabit Transceiver IP}

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

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

SATA Standard Information

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 II: Electrical Specification; Revision 1.0, 5/2004
SATA PHY Interface Specification [SAPIS]

Serial ATA {Serial ATA International Organization (SATA-IO)}

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.

SATA Data pinout

SATA PinOut, Data
Pin # Signal name Signal Description
1 GND Ground
2 A+ Transmit +
3 A- Transmit -
4 GND Ground
5 B- Receive -
6 B+ Receive +
7 GND Ground

SATA Power pinout

SATA PinOut, Power
Pin # Signal name Signal Description
1 V33 3.3v Power
2 V33 3.3v Power
3 V33 3.3v Power, Pre-charge, 2nd mate
4 Ground 1st Mate
5 Ground 2nd Mate
6 Ground 3rd Mate
7 V5 5v Power, pre-charge, 2nd mate
8 V5 5v Power
9 V5 5v Power
10 Ground 2nd Mate
11 Reserved -
12 Ground 1st Mate
13 V12 12v Power, Pre-charge, 2nd mate
14 V12 12v Power
15 V12 12v Power

PATA Power pinout

IDE Power Connector Pin Out
Pin # Signal Function 18 AWG Wire
1 +12V DC Yellow
2 +12V Return Black
3 +5V Return Black
4 +5V DC Red

SATA signal names are with respect to the Host [Motherboard], the device connected to the host reverses the signal names. Transmit pins connect to Receive pins on the other device. The SATA connector is keyed at pin 1. These pin outs for the Serial ATA connector are not compatible with the legacy PATA connector.

SATA Connectors and Cable Manufacturers

The cable uses two shielded pairs to carry data. The wire gauge 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 18 inch 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 case.

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}

Delphi {Serial ATA Cables}

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

Molex {Serial ATA Connectors and Cables Assemblies}

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}

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Modified 2/11/12
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