Serial ATA Bus

Serial ATA (Advanced Technology Attachment)



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Serial ATA Signal Assignments

SATA Unit to Cable Interface
SATA Cabling Diagram

SATA Interface
The Serial ATA [SATA] bus is defined over two separate connectors,
one connector for the data lines and one for the power lines [shown left].
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 cable
to supply a connection which is more rugged and reliable then the SATA-1 power connection.
The PATA interface is not visible in the diagram.

The Serial ATA interface cable consists of four conductors in two differential pairs,
plus three ground connections.
The cable size may be 30 to 26 AWG with a maximum length of one meter (39.37 inches).





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




To date all new mother board designs are shipping with one or more SATA interfaces. Some motherboards also have the Legacy PATA interface to handle older Hard Disk Drives [HDD]. Place your main Disk Drives on the Serial ATA interface if possible and the older drives on the PATA interface ~ as a back-up drive. The SATA interface is much faster then the PATA interface, but depending on the disk platter speed, a transfer increase may not be seen. Here is a chart of Hard Drive Transfer Speeds.

SATA signal names are with respect to the Host, 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 Serial ATA interface [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 3 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. 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.



Related SATA acronyms;
Direct Attached Storage [DAS], is a drive connected to a server.
Networked Attached Storage [NAS], is a drive connected to a network.
Storage Area Network [SAN], is a system of drives.
Direct Access Storage Devices [DASD], is a fast-access drive connected to computer.
Host Bus Adapter [HBA], is an interface between a computer and a drive.


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Modified: 12/15/11
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