Serial ATA (Advanced Technology Attachment)
[SATA Description] [Interface ICs]
[SATA Connector/Cable] [SATA
Pinout]
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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 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.
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}
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)}
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.
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 |
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 |
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.
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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