The Ready LED Out signal is designed to pull down the cathode of an LED. The anode is attached to the proper +3.3 volt supply through an appropriate current limiting resistor. The LED and the current limiting resis- tor are external to the drive. See Table 17 for the output characteristics of the LED drive signals.

Table 17:

LED drive signal

 

 

 

 

 

State

 

Test condition

Output voltage

 

 

 

 

LED off, high

 

0 V ≤ VOH ≤ 3.6 V

-100 μA < IOH < 100 μA

LED on, low

 

IOL = 15 mA

0 ≤ VOL ≤ 0.225 V

12.5.2Differential signals

The drive SAS differential signals comply with the intra-enclosure (internal connector) requirements of the SAS standard.

Table 18 defines the general interface characteristics.

Table 18: General interface characteristics

Characteristic

Units

1.5Gb/s

3.0Gb/s

6.0Gb/s

 

 

 

 

 

Bit rate (nominal)

Mbaud

1,500

3,000

6,000

 

 

 

 

 

Unit interval (UI)(nominal)

ps

666.6

333.3

166.6

 

 

 

 

 

Impedance (nominal, differential )

ohm

100

100

100

 

 

 

 

 

Transmitter transients, maximum

V

± 1.2

± 1.2

± 1.2

 

 

 

 

 

Receiver transients, maximum

V

± 1.2

± 1.2

± 1.2

 

 

 

 

 

12.6SAS-2 Specification Compliance

Seagate SAS-2 drives are entirely compatible with the latest SAS-2 Specification (T10/1760-D) Revision 16.

The most important characteristic of the SAS-2 drive at 6Gb/s is that the receiver is capable of adapting the equalizer to optimize the receive margins. The SAS-2 drive has two types of equalizers:

1.A Decision Feedback Equalizer (DFE) which utilizes the standard SAS-2 training pattern transmitted dur- ing the SNW-3 training gap. The DFE circuit can derive an optimal equalization characteristic to compen- sate for many of the receive losses in the system.

2.A Feed Forward Equalizer (FFE) optimized to provide balanced receive margins over a range of channels bounded by the best and worst case channels as defined by the relevant ANSI standard.

12.7Additional information

Please contact your Seagate representative for SAS electrical details, if required.

For more information about the Phy, Link, Transport, and Applications layers of the SAS interface, refer to the Seagate SAS Interface Manual, part number 100293071.

For more information about the SCSI commands used by Seagate SAS drives, refer to the Seagate SCSI Commands Reference Manual, part number 100293068.

Constellation ES.1 SAS Product Manual, Rev. E

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Seagate ST500NM0021 manual SAS-2 Specification Compliance, Additional information, LED drive signal, Differential signals
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ST2000NM0001, ST1000NM0041, ST500NM0001, ST2000NM0021, ST1000NM0021 specifications

Seagate is a renowned leader in data storage solutions, offering a wide array of hard disk drives (HDDs) suitable for various applications. Among their product lineup, the Seagate ST2000NM0041, ST500NM0021, ST500NM0041, ST1000NM0001, and ST1000NM0021 stand out as reliable options tailored for enterprise environments and general storage needs.

The Seagate ST2000NM0041 is a 2TB 7200 RPM drive designed for high-performance workloads in data centers. One of its key features is the use of the SATA III interface, providing data transfer speeds of up to 6 Gbps, ensuring quick access to data. This model supports advanced error recovery controls and features enhanced power management capabilities, which contribute to its reliable performance and energy efficiency.

Next, the ST500NM0021 and ST500NM0041 are both 500GB drives that cater to different consumer needs. The ST500NM0021 is a 5400 RPM drive, typically used in scenarios where lower power consumption is vital, such as in compact systems or external storage configurations. Its efficient design enables quieter operation, making it ideal for environments that require minimal noise. Conversely, the ST500NM0041 operates at a speed of 7200 RPM, making it suitable for more demanding applications that require swift read and write speeds. Both models utilize Serial ATA for connectivity, ensuring compatibility with a wide range of systems.

The ST1000NM0001 and ST1000NM0021 are 1TB drives that provide versatility across different platforms. Similar to their 500GB counterparts, the ST1000NM0001 features a 7200 RPM speed, optimizing performance for applications requiring faster data processing. In contrast, the ST1000NM0021 operates at 5400 RPM, designed for users prioritizing energy efficiency over speed, like in desktop and external storage solutions. Each of these drives supports advanced technologies such as Native Command Queuing (NCQ), which enhances performance by allowing multiple commands to be executed simultaneously.

Overall, the Seagate ST series hard drives offer flexible storage options for a variety of applications. With their robust features, including varied RPM speeds, power management, and compatibility with SATA connections, these drives cater to the needs of both consumer and enterprise markets, establishing Seagate as a trusted provider in the storage arena.
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