SNLS466A September   2013  – March 2014 DS125BR401A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Terminal Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Electrical Characteristics — Serial Management Bus Interface
    7. 6.7 Timing Requirements Serial Bus Interface
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
      1. 7.2.1 Functional Datapath Blocks
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Terminal Control Mode:
      2. 7.4.2 SMBus Mode:
      3. 7.4.3 MODE operation with SMBus Registers
    5. 7.5 Signal Conditioning Settings
    6. 7.6 Programming
    7. 7.7 Register Maps
      1. 7.7.1 Transfer Of Data Via The SMBus
      2. 7.7.2 SMBus Transactions
      3. 7.7.3 Writing a Register
      4. 7.7.4 Reading a Register
  8. 8 Applications and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Signal Integrity in SAS-3 Applications
      2. 8.1.2 RX-Detect in SAS/SATA Applications
      3. 8.1.3 Signal Integrity in PCIe Applications
      4. 8.1.4 MODE operation with SMBus Registers
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Performance Plots
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Trademarks
    2. 11.2 Electrostatic Discharge Caution
    3. 11.3 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7 Detailed Description

7.1 Overview

The DS125BR401A compensates for lossy FR-4 printed circuit board backplanes and balanced cables. The DS125BR401A operates in 3 modes: Terminal Control Mode (ENSMB = 0), SMBus Slave Mode (ENSMB = 1) and SMBus Master Mode (ENSMB = float) to load register information from external EEPROM; please refer to SMBus Master Mode for additional information.

7.2 Functional Block Diagram

B-Channel Datapath

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A-Channel Datapath

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7.2.1 Functional Datapath Blocks

The Channel-B datapath is designed to handle higher levels of input attenuation and includes an output with a soft-limiting function to provide some transparency for Rx-Tx training in SAS-3 and other standards. The Channel-A datapath has less input equalization coupled with a linear driver. This combination has a high level of transparency, achieving greater drive distance in SAS-3 applications which utilize Rx-Tx training. The asymmetrical channel design follows the application diagram in .

The Channel-A and Channel-B data-paths are optimized to work as a transparent driver and a transparent receiver. The typical DS125BR401A system placement breaks a long transmission line into two pieces. This often leads to one short and one long piece, this unequal partition places different demands on A and B-Channels. To maximize channel extension with the DS125BR401A, connect the A-Channel Inputs to the channel segment with the lowest attenuation to the SAS-3 Tx.

7.3 Feature Description

The 4-level input Terminals utilize a resistor divider to help set the 4 valid levels and provide a wider range of control settings when ENSMB=0. There is an internal 30K pull-up and a 60K pull-down connected to the package Terminal. These resistors, together with the external resistor connection combine to achieve the desired voltage level. Using the 1K pull-up, 1K pull-down, no connect, and 20K pull-down provide the optimal voltage levels for each of the four input states.

Table 1. 4–Level Control Terminal Settings

Level Setting 3.3V Mode 2.5V Mode
0 Tie 1kΩ to GND 0.10 V 0.08 V
R Tie 20kΩ to GND 1/3 x VIN 1/3 x VDD
Float Float (leave Terminal open) 2/3 x VIN 2/3 x VDD
1 Tie 1kΩ to VIN or VDD VIN - 0.05 V VDD - 0.04 V

Typical 4-Level Input Thresholds

  • Level 1 - 2 = 0.2 * VIN or VDD
  • Level 2 - 3 = 0.5 * VIN or VDD
  • Level 3 - 4 = 0.8 * VIN or VDD

In order to minimize the startup current associated with the integrated 2.5V regulator the 1K pull-up / pull-down resistors are recommended. If several 4 level inputs require the same setting, it is possible to combine two or more 1K resistors into a single lower value resistor. As an example; combining two inputs with a single 500 Ohm resistor is a good way to save board space.

7.4 Device Functional Modes

7.4.1 Terminal Control Mode:

When in Terminal mode (ENSMB = 0), equalization and de-emphasis can be selected via Terminal for each side independently. When de-emphasis is asserted VOD is automatically adjusted per Table 7. For PCIe applications, the RXDET Terminals provides automatic and manual control for input termination (50Ω or >50KΩ). MODE_B setting is also Terminal controllable with Terminal selections (Gen 1/2, auto detect, and SAS-3 / PCIe Gen 3). The receiver electrical signal detect threshold is also adjustable via the SD_TH Terminal. For A-Side Channels this can only be used for status information, on B-Side Channels this threshold will determine when the output state, Mute if no signal is present or active with a valid input signal detected .

7.4.2 SMBus Mode:

When in SMBus mode (ENSMB = 1), the VOD (output amplitude), equalization, de-emphasis, and termination disable features are all programmable on a individual lane basis, instead of grouped by A or B as in the Terminal mode case. Upon assertion of ENSMB, the EQx and DEMx functions revert to register control immediately. The EQx and DEMx Terminals are converted to AD0-AD3 SMBus address inputs. The other external control Terminals (MODE_B, RXDET and SD_TH) remain active unless their respective registers are written to and the appropriate override bit is set, in which case they are ignored until ENSMB is driven low (Terminal mode). On power-up or when ENSMB is driven low all registers are reset to their default state. If PWDN is asserted while ENSMB is high, the registers retain their current state.

Equalization settings accessible via the Terminal controls were chosen to meet the needs of most high speed applications. If additional fine tuning or adjustment is needed, additional equalization settings can be accessed via the SMBus registers. Each input has a total of 256 possible equalization settings. The tables show the 16 settings when the device is in Terminal mode. When using SMBus mode, the equalization, VOD and de- Emphasis levels are set by registers.

The 4-level input Terminals utilize a resistor divider to help set the 4 valid levels and provide a wider range of control settings when ENSMB=0. There is an internal 30K pull-up and a 60K pull-down connected to the package Terminal. These resistors, together with the external resistor connection combine to achieve the desired voltage level. Using the 1K pull-up, 1K pull-down, no connect, and 20K pull-down provide the optimal voltage levels for each of the four input states.

Table 2. RX-Detect Settings

PWDN
(Terminal 52)		 RXDET
(Terminal 22)		 SMBus REG
Bit[3:2]		 INPUT TERMINATION RECOMMENDED USE COMMENTS
0 0 00 Hi-Z X Manual RX-Detect, input is high impedance mode
0 Tie 20kΩ
to GND		 01 Pre Detect: Hi-Z
Post Detect: 50 Ω		 PCIe only Auto RX-Detect, outputs test every 12 msec for 600 msec then stops; termination is Hi-Z until RX detection; once detected input termination is 50 Ω

Reset function by pulsing PWDN high for 5 usec then low again
0 Float
(Default)		 10 Pre Detect: Hi-Z
Post Detect: 50 Ω		 PCIe only Auto RX-Detect, outputs test every 12 msec until detection occurs; termination is Hi-Z until RX detection; once detected input termination is 50 Ω
0 1 11 50 Ω All Others Manual RX-Detect, input is 50 Ω
1 X High Impedance X Power down mode, input is Hi-Z, output drivers are disabled

Used to reset RX-Detect State Machine when held high for 5 usec

Table 3. OOB And Signal Detect Threshold Level(1)

SD_TH
(Terminal 26)		 SMBus REG BIT [3:2] and [1:0] [3:2] ASSERT LEVEL (mVp-p) [1:0] DE-ASSERT LEVEL (mVp-p)
3 Gbps 12 Gbps 3 Gbps 12 Gbps
0 10 18 75 14 55
R 01 12 40 8 22
F (default) 00 15 50 11 37
1 11 16 58 12 45
(1) VDD = 2.5V, 25°C, 11 00 11 00 pattern at 3 Gbps and 101010 pattern at 12 Gbps

Table 4. Mode Operation With Terminal Control

MODE_B
(Terminal 21)		 Driver characteristics PCIe SAS
SATA		 10GbE CPRI
OBSAI		 SRIO
(R)XAUI		 Interlaken
Infiniband
0 Limiting X (≤ 6G) X X X X
R Transparent without DE
F (default) Automatic X
1 Transparent with DE X (SAS-3)

7.4.3 MODE operation with SMBus Registers

When in SMBus mode (Slave or Master), the MODE Terminal retains control of the output driver characteristics. In order to override this control function, Register 0x08[2] must be written with a "1". Writing this bit enables MODE control of each channel individually using the channel registers defined in Table 9. For Channel-A outputs the MODE control bit is not functional. The outputs are always in a linear mode of operation. Changing these bits while Register 0x08[2]=1 will dramatically reduce the output amplitude.

7.5 Signal Conditioning Settings

Information in Table 5 and Table 6 shows the level of CTLE or equalization gain for Channel-B and Channel-A.

Table 5. B-Channel Equalizer Settings

Level EQB1 EQB0 EQ – 8 bits [7:0] dB at
1.5 GHz		 dB at
2.5 GHz		 dB at
4 GHz		 dB at
6 GHz		 Suggested Use(1)
1 0 0 0000 0000 = 0x00 2.5 3.5 3.8 3.1 FR4 < 5 inch trace
2 0 R 0000 0001 = 0x01 3.8 5.4 6.7 6.7 FR4 5-10 inch trace
3 0 Float 0000 0010 = 0x02 5.0 7.0 8.4 8.4 FR4 10 inch trace
4 0 1 0000 0011 = 0x03 5.9 8.0 9.3 9.1 FR4 15-20 inch trace
5 R 0 0000 0111 = 0x07 7.4 10.3 12.8 13.7 FR4 20-30 inch trace
6 R R 0001 0101 = 0x15 6.9 10.2 13.9 16.2 FR4 25-30 inch trace
7 R Float 0000 1011 = 0x0B 9.0 12.4 15.3 15.9 FR4 25-30 inch trace
8 R 1 0000 1111 = 0x0F 10.2 13.8 16.7 17.0 8m, 30awg cable
9 Float 0 0101 0101 = 0x55 8.5 12.6 17.5 20.7 > 8m cable
10 Float R 0001 1111 = 0x1F 11.7 16.2 20.3 21.8
11 Float Float 0010 1111 = 0x2F 13.2 18.3 22.8 23.6
12 Float 1 0011 1111 = 0x3F 14.4 19.8 24.2 24.7
13 1 0 1010 1010 = 0xAA 14.4 20.5 26.4 28.0
14 1 R 0111 1111 = 0x7F 16.0 22.2 27.8 29.2
15 1 Float 1011 1111 = 0xBF 17.6 24.4 30.2 30.9
16 1 1 1111 1111 = 0xFF 18.7 25.8 31.6 31.9
(1) Cable and FR4 lengths are for reference only. FR4 lengths based on a 100 Ohm differential stripline with 5-mil traces and 8-mil trace separation. Optimal EQ setting should be determined via simulation and prototype verification.

Table 6. A-Channel Equalizer Settings

Level EQA1 EQA0 EQ – 8 bits [7:0] dB at
1.5 GHz		 dB at
2.5 GHz		 dB at
4 GHz		 dB at
6 GHz		 Suggested Use(1)
1 N/A 0 xxxx xx00 = 0x00 2.5 3.5 3.8 3.1
2 N/A R xxxx xx01 = 0x01 3.8 5.4 6.7 6.7
3 N/A Float xxxx xx10 = 0x02 5.0 7.0 8.4 8.4
4 N/A 1 xxxx xx11 = 0x03 5.9 8.0 9.3 9.1 SAS-3

Table 7. B-Channel Output Voltage And De-Emphasis Settings

Level DEMB1 DEMB0 VOD Vp-p DEM dB(1) Inner Amplitude
Vp-p		 Suggested Use(2)
1 0 0 0.8 0 0.8 FR4 <5 inch trace
2 0 R 0.9 0 0.9 FR4 <5 inch trace
3 0 Float 0.9 - 3.5 0.6 FR4 10 inch trace
4 0 1 1.0 0 1.0 FR4 <5 inch trace
5 R 0 1.0 - 3.5 0.7 FR4 10 inch trace
6 R R 1.0 - 6 0.5 FR4 15 inch trace
7 R Float 1.1 0 1.1 FR4 <5 inch trace
8 R 1 1.1 - 3.5 0.7 FR4 10 inch trace
9 Float 0 1.1 - 6 0.6 FR4 15 inch trace
10 Float R 1.2 0 1.2 FR4 <5 inch trace
11 Float Float 1.2 - 3.5 0.8 FR4 10 inch trace
12 Float 1 1.2 - 6 0.6 FR4 15 inch trace
13 1 0 1.3 0 1.3 FR4 <5 inch trace
14 1 R 1.3 - 3.5 0.9 FR4 10 inch trace
15 1 Float 1.3 - 6 0.7 FR4 15 inch trace
16 1 1 1.3 - 9 0.5 FR4 20 inch trace
(1) The VOD output amplitude and DEM de-emphasis levels are set with the DEMB[1:0] Terminals.
(2) FR4 lengths are for reference only. FR4 lengths based on a 100 Ohm differential stripline with 5-mil traces and 8-mil trace separation. Optimal DEM settings should be determined via simulation and prototype verification.

Table 8. A-Channel Output Voltage And De-Emphasis Settings

Level DEMA1 DEMA0 VID Vp-p DEM Setting(1) VOD Vp-p
1 0 0 1.0 0 0.70
2 0 R 1.0 0 0.78
4 0 1 1.0 0 0.83
7 R Float 1.0 0 0.88
10 Float R 1.0 0 0.91
13 1 0 1.0 0 1.00
(1) The VOD output amplitude is set with the DEMA[1:0] Terminals. For SAS-3 operation the DEM level is typically left at 0 dB (SMBus control = 000'b) in order to keep the output dynamic range as large as possible. DEM settings other than 0 dB or 000'b will decrease the output dynamic range and act to limit the OUTA VOD. When operating in Terminal Mode in a SAS3 environment it is recommended to use DEMA[1:0] = 10'b.

7.6 Programming

The DS125BR401A device supports reading directly from an external EEPROM device by implementing SMBus Master mode. When using the SMBus master mode, the DS125BR401A will read directly from specific location in the external EEPROM. When designing a system for using the external EEPROM, the user needs to follow these specific guidelines.

  • Maximum EEPROM size is 8 kbits (1024 x 8-bit).
  • Set ENSMB = Float — enable the SMBus master mode.
  • The external EEPROM device address byte must be 0xA0'h and capable of 400 kHz operation at 2.5V and 3.3V supply.
  • Set the AD[3:0] inputs for SMBus address byte. When the AD[3:0] = 0000'b, the device address byte is B0'h.

When tying multiple DS125BR401A devices to the SDA and SCL bus, use these guidelines to configure the devices.

  • Use SMBus AD[3:0] address bits so that each device can loaded it's configuration from the EEPROM. Example below is for 4 devices. The first device in the sequence must be address 0xB0'h, subsequent devices must follow the address order listed below.
    • U1: AD[3:0] = 0000 = 0xB0'h,
    • U2: AD[3:0] = 0001 = 0xB2'h,
    • U3: AD[3:0] = 0010 = 0xB4'h,
    • U4: AD[3:0] = 0011 = 0xB6'h
  • Use a pull-up resistor on SDA and SCL; value = 2k ohms
  • Daisy-chain READEN# (Terminal 26) and ALL_DONE# (Terminal 27) from one device to the next device in the sequence so that they do not compete for the EEPROM at the same time.
    1. Tie READEN# of the 1st device in the chain (U1) to GND
    2. Tie ALL_DONE# of U1 to READEN# of U2
    3. Tie ALL_DONE# of U2 to READEN# of U3
    4. Tie ALL_DONE# of U3 to READEN# of U4
    5. Optional: Tie ALL_DONE# output of U4 to a LED to show the devices have been loaded successfully

Below is an example of a 2 kbits (256 x 8-bit) EEPROM in hex format for the DS125BR401A device. The first 3 bytes of the EEPROM always contain a header common and necessary to control initialization of all devices connected to the I2C bus. CRC enable flag to enable/disable CRC checking. If CRC checking is disabled, a fixed pattern (8’hA5) is written/read instead of the CRC byte from the CRC location, to simplify the control. There is a MAP bit to flag the presence of an address map that specifies the configuration data start in the EEPROM. If the MAP bit is not present the configuration data start address is derived from the DS125BR401A address and the configuration data size. A bit to indicate an EEPROM size > 256 bytes is necessary to properly address the EEPROM. There are 37 bytes of data size for each DS125BR401A device.

:2000000000001000000407002FAD4002FAD4002FAD4002FAD409805F5A8005F5A8005F5AD0 :200020008005F5A800005454000000000000000000000000000000000000000000000000F6 :20006000000000000000000000000000000000000000000000000000000000000000000080 :20008000000000000000000000000000000000000000000000000000000000000000000060 :2000A000000000000000000000000000000000000000000000000000000000000000000040 :2000C000000000000000000000000000000000000000000000000000000000000000000020 :2000E000000000000000000000000000000000000000000000000000000000000000000000 :200040000000000000000000000000000000000000000000000000000000000000000000A0

Note: The maximum EEPROM size supported is 8 kbits (1024 x 8 bits).

Table 9. EEPROM Register Map - Single Device With Default Value

EEPROM Address Byte Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 BIt 0
Description 0 CRC EN Address Map Present EEPROM > 256 Bytes RES DEVICE COUNT[3] DEVICE COUNT[2] DEVICE COUNT[1] DEVICE COUNT[0]
Value 00 0 0 0 0 0 0 0 0
Description 1 RES RES RES RES RES RES RES RES
Value 00 0 0 0 0 0 0 0 0
Description 2 Max EEPROM Burst size[7] Max EEPROM Burst size[6] Max EEPROM Burst size[5] Max EEPROM Burst size[4] Max EEPROM Burst size[3] Max EEPROM Burst size[2] Max EEPROM Burst size[1] Max EEPROM Burst size[0]
Value 00 0 0 0 0 0 0 0 0
Description 3 PWDN_CH7 PWDN_CH6 PWDN_CH5 PWDN_CH4 PWDN_CH3 PWDN_CH2 PWDN_CH1 PWDN_CH0
SMBus Register 0x01 [7] 0x01 [6] 0x01 [5] 0x01 [4] 0x01 [3] 0x01 [2] 0x01 [1] 0x01 [0]
Value 00 0 0 0 0 0 0 0 0
Description 4 Reserved Reserved Reserved Reserved Ovrd_PWDN CH7_EQ_LIM CH6_EQ_LIM CH5_EQ_LIM
SMBus Register 0x02 [5] 0x02 [4] 0x02 [3] 0x02 [2] 0x02 [0] 0x04 [7] 0x04 [6] 0x04 [5]
Value 00 0 0 0 0 0 0 0 0
Description 5 CH4_EQ_LIM CH3_EQ_LIM CH2_EQ_LIM CH1_EQ_LIM CH0_EQ_LIM rxdet_btb_en Ovrd_SD_TH Reserved
SMBus Register 0x04 [4] 0x04 [3] 0x04 [2] 0x04 [1] 0x04 [0] 0x06 [4] 0x08 [6] 0x08 [5]
Value 04 0 0 0 0 0 1 0 0
Description 6 Ovrd_IDLE Ovrd_RX_DET Ovrd_MODE Reserved Reserved rxdet_delay_2 rxdet_delay_1 rxdet_delay_0
SMBus Register 0x08 [4] 0x08 [3] 0x08 [2] 0x08 [1] 0x08 [0] 0x0B [6] 0x0B [5] 0x0B [4]
Value 07 0 0 0 0 0 1 1 1
Description 7 rate_delay_3 rate_delay_2 rate_delay_1 rate_delay_0 CH0_Idle_auto CH0_Idle_sel CH0_Rxdet_1 CH0_Rxdet_0
SMBus Register 0x0B [3] 0x0B [2] 0x0B [1] 0x0B [0] 0x0E [5] 0x0E [4] 0x0E [3] 0x0E [2]
Value 00 0 0 0 0 0 0 0 0
Description 8 CH0_EQ_7 CH0_EQ_6 CH0_EQ_5 CH0_EQ_4 CH0_EQ_3 CH0_EQ_2 CH0_EQ_1 CH0_EQ_0
SMBus Register 0x0F [7] 0x0F [6] 0x0F [5] 0x0F [4] 0x0F [3] 0x0F [2] 0x0F [1] 0x0F [0]
Value 2F 0 0 1 0 1 1 1 1
Description 9 CH0_SCP CH0_MODE Reserved Reserved Reserved CH0_VOD_2 CH0_VOD_1 CH0_VOD_0
SMBus Register 0x10 [7] 0x10 [6] 0x10 [5] 0x10 [4] 0x10 [3] 0x10 [2] 0x10 [1] 0x10 [0]
Value AD 1 0 1 0 1 1 0 1
Description A CH0_DEM_2 CH0_DEM_1 CH0_DEM_0 Reserved CH0_THa_1 CH0_THa_0 CH0_THd_1 CH0_THd_0
SMBus Register 0x11 [2] 0x11 [1] 0x11 [0] 0x12 [7] 0x12 [3] 0x12 [2] 0x12 [1] 0x12 [0]
Value 40 0 1 0 0 0 0 0 0
Description B CH1_Idle_auto CH1_Idle_sel CH1_Rxdet_1 CH1_Rxdet_0 CH1_EQ_7 CH1_EQ_6 CH1_EQ_5 CH1_EQ_4
SMBus Register 0x15 [5] 0x15 [4] 0x15 [3] 0x15 [2] 0x16 [7] 0x16 [6] 0x16 [5] 0x16 [4]
Value 02 0 0 0 0 0 0 1 0
Description C CH1_EQ_3 CH1_EQ_2 CH1_EQ_1 CH1_EQ_0 CH1_SCP CH1_MODE Reserved Reserved
SMBus Register 0x16 [3] 0x16 [2] 0x16 [1] 0x16 [0] 0x17 [7] 0x17 [6] 0x17 [5] 0x17 [4]
Value FA 1 1 1 1 1 0 1 0
Description D Reserved CH1_VOD_2 CH1_VOD_1 CH1_VOD_0 CH1_DEM_2 CH1_DEM_1 CH1_DEM_0 Reserved
SMBus Register 0x17 [3] 0x17 [2] 0x17 [1] 0x17 [0] 0x18 [2] 0x18 [1] 0x18 [0] 0x19 [7]
Value D4 1 1 0 1 0 1 0 0
Description E CH1_THa_1 CH1_THa_0 CH1_THd_1 CH1_THd_0 CH2_Idle_auto CH2_Idle_sel CH2_Rxdet_1 CH2_Rxdet_0
SMBus Register 0x19 [3] 0x19 [2] 0x19 [1] 0x19 [0] 0x1C [5] 0x1C [4] 0x1C [3] 0x1C [2]
Value 00 0 0 0 0 0 0 0 0
Description F CH2_EQ_7 CH2_EQ_6 CH2_EQ_5 CH2_EQ_4 CH2_EQ_3 CH2_EQ_2 CH2_EQ_1 CH2_EQ_0
SMBus Register 0x1D [7] 0x1D [6] 0x1D [5] 0x1D [4] 0x1D [3] 0x1D [2] 0x1D [1] 0x1D [0]
Value 2F 0 0 1 0 1 1 1 1
Description 10 CH2_SCP CH2_MODE Reserved Reserved Reserved CH2_VOD_2 CH2_VOD_1 CH2_VOD_0
SMBus Register 0x1E [7] 0x1E [6] 0x1E [5] 0x1E [4] 0x1E [3] 0x1E [2] 0x1E [1] 0x1E [0]
Value AD 1 0 1 0 1 1 0 1
Description 11 CH2_DEM_2 CH2_DEM_1 CH2_DEM_0 Reserved CH2_THa_1 CH2_THa_0 CH2_THd_1 CH2_THd_0
SMBus Register 0x1F [2] 0x1F [1] 0x1F [0] 0x20 [7] 0x20 [3] 0x20 [2] 0x20 [1] 0x20 [0]
Value 40 0 1 0 0 0 0 0 0
Description 12 CH3_Idle_auto CH3_Idle_sel CH3_Rxdet_1 CH3_Rxdet_0 CH3_EQ_7 CH3_EQ_6 CH3_EQ_5 CH3_EQ_4
SMBus Register 0x23 [5] 0x23 [4] 0x23 [3] 0x23 [2] 0x24 [7] 0x24 [6] 0x24 [5] 0x24 [4]
Value 02 0 0 0 0 0 0 1 0
Description 13 CH3_EQ_3 CH3_EQ_2 CH3_EQ_1 CH3_EQ_0 CH3_SCP CH3_MODE Reserved Reserved
SMBus Register 0x24 [3] 0x24 [2] 0x24 [1] 0x24 [0] 0x25 [7] 0x25 [6] 0x25 [5] 0x25 [4]
Value FA 1 1 1 1 1 0 1 0
Description 14 Reserved CH3_VOD_2 CH3_VOD_1 CH3_VOD_0 CH3_DEM_2 CH3_DEM_1 CH3_DEM_0 Reserved
SMBus Register 0x25 [3] 0x25 [2] 0x25 [1] 0x25 [0] 0x26 [2] 0x26 [1] 0x26 [0] 0x27 [7]
Value D4 1 1 0 1 0 1 0 0
Description 15 CH3_THa_1 CH3_THa_0 CH3_THd_1 CH3_THd_0 ovrd_fast_idle hi_idle_th CH0-3 hi_idle_thCH4-7 fast_idle CH0-3
SMBus Register 0x27 [3] 0x27 [2] 0x27 [1] 0x27 [0] 0x28 [6] 0x28 [5] 0x28 [4] 0x28 [3]
Value 09 0 0 0 0 1 0 0 1
Description 16 fast_idle CH4-7 low_gain CH0-3 low_gain CH4-7 CH4_Idle_auto CH4_Idle_sel CH4_Rxdet_1 CH4_Rxdet_0 Reserved
SMBus Register 0x28 [2] 0x28 [1] 0x28 [0] 0x2B [5] 0x2B [4] 0x2B [3] 0x2B [2] 0x2C [7]
Value 80 1 0 0 0 0 0 0 0
Description 17 Reserved Reserved Reserved Reserved Reserved CH4_EQ_1 CH4_EQ_0 CH4_SCP
SMBus Register 0x2C [6] 0x2C [5] 0x2C [4] 0x2C [3] 0x2C [2] 0x2C [1] 0x2C [0] 0x2D [7]
Value 5F 0 1 0 1 1 1 1 1
Description 18 Reserved Reserved Reserved Reserved CH4_VOD_2 CH4_VOD_1 CH4_VOD_0 CH4_DEM_2
SMBus Register 0x2D [6] 0x2D [5] 0x2D [4] 0x2D [3] 0x2D [2] 0x2D [1] 0x2D [0] 0x2E [2]
Value 5A 0 1 0 1 1 0 1 0
Description 19 CH4_DEM_1 CH4_DEM_0 Reserved CH4_THa_1 CH4_THa_0 CH4_THd_1 CH4_THd_0 CH5_Idle_auto
SMBus Register 0x2E [1] 0x2E [0] 0x2F [7] 0x2F [3] 0x2F [2] 0x2F [1] 0x2F [0] 0x32 [5]
Value 80 1 0 0 0 0 0 0 0
Description 1A CH5_Idle_sel CH5_Rxdet_1 CH5_Rxdet_0 Reserved Reserved Reserved Reserved Reserved
SMBus Register 0x32 [4] 0x32 [3] 0x32 [2] 0x33 [7] 0x33 [6] 0x33 [5] 0x33 [4] 0x33 [3]
Value 05 0 0 0 0 0 1 0 1
Description 1B Reserved CH5_EQ_1 CH5_EQ_0 CH5_SCP Reserved Reserved Reserved Reserved
SMBus Register 0x33 [2] 0x33 [1] 0x33 [0] 0x34 [7] 0x34 [6] 0x34 [5] 0x34 [4] 0x34 [3]
Value F5 1 1 1 1 0 1 0 1
Description 1C CH5_VOD_2 CH5_VOD_1 CH5_VOD_0 CH5_DEM_2 CH5_DEM_1 CH5_DEM_0 Reserved CH5_THa_1
SMBus Register 0x34 [2] 0x34 [1] 0x34 [0] 0x35 [2] 0x35 [1] 0x35 [0] 0x36 [7] 0x36 [3]
Value A8 1 0 1 0 1 0 0 0
Description 1D CH5_THa_0 CH5_THd_1 CH5_THd_0 CH6_Idle_auto CH6_Idle_sel CH6_Rxdet_1 CH6_Rxdet_0 Reserved
SMBus Register 0x36 [2] 0x36 [1] 0x36 [0] 0x39 [5] 0x39 [4] 0x39 [3] 0x39 [2] 0x3A [7]
Value 00 0 0 0 0 0 0 0 0
Description 1E Reserved Reserved Reserved Reserved Reserved CH6_EQ_1 CH6_EQ_0 CH6_SCP
SMBus Register 0x3A [6] 0x3A [5] 0x3A [4] 0x3A [3] 0x3A [2] 0x3A [1] 0x3A [0] 0x3B [7]
Value 5F 0 1 0 1 1 1 1 1
Description 1F Reserved Reserved Reserved Reserved CH6_VOD_2 CH6_VOD_1 CH6_VOD_0 CH6_DEM_2
SMBus Register 0x3B [6] 0x3B [5] 0x3B [4] 0x3B [3] 0x3B [2] 0x3B [1] 0x3B [0] 0x3C [2]
Value 5A 0 1 0 1 1 0 1 0
Description 20 CH6_DEM_1 CH6_DEM_0 Reserved CH6_THa_1 CH6_THa_0 CH6_THd_1 CH6_THd_0 CH7_Idle_auto
SMBus Register 0x3C [1] 0x3C [0] 0x3D [7] 0x3D [3] 0x3D [2] 0x3D [1] 0x3D [0] 0x40 [5]
Value 80 1 0 0 0 0 0 0 0
Description 21 CH7_Idle_sel CH7_Rxdet_1 CH7_Rxdet_0 Reserved Reserved Reserved Reserved Reserved
SMBus Register 0x40 [4] 0x40 [3] 0x40 [2] 0x41 [7] 0x41 [6] 0x41 [5] 0x41 [4] 0x41 [3]
Value 05 0 0 0 0 0 1 0 1
Description 22 Reserved CH7_EQ_1 CH7_EQ_0 CH7_SCP Reserved Reserved Reserved Reserved
SMBus Register 0x41 [2] 0x41 [1] 0x41 [0] 0x42 [7] 0x42 [6] 0x42 [5] 0x42 [4] 0x42 [3]
Value F5 1 1 1 1 0 1 0 1
Description 23 CH7_VOD_2 CH7_VOD_1 CH7_VOD_0 CH7_DEM_2 CH7_DEM_1 CH7_DEM_0 Reserved CH7_THa_1
SMBus Register 0x42 [2] 0x42 [1] 0x42 [0] 0x43 [2] 0x43 [1] 0x43 [0] 0x44 [7] 0x44 [3]
Value A8 1 0 1 0 1 0 0 0
Description 24 CH7_THa_0 CH7_THd_1 CH7_THd_0 Reserved Reserved Reserved Reserved Reserved
SMBus Register 0x44 [2] 0x44 [1] 0x44 [0] 0x47 [3] 0x47 [2] 0x47 [2] 0x47 [0] 0x48 [7]
Value 00 0 0 0 0 0 0 0 0
Description 25 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved
SMBus Register 0x48 [6] 0x4C [7] 0x4C [6] 0x4C [5] 0x4C [4] 0x4C [3] 0x4C [0] 0x59 [0]
Value 00 0 0 0 0 0 0 0 0
Description 26 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved
SMBus Register 0x5A [7] 0x5A [6] 0x5A [5] 0x5A [4] 0x5A [3] 0x5A [2] 0x5A [1] 0x5A [0]
Value 54 0 1 0 1 0 1 0 0
Description 27 Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved
SMBus Register 0x5B [7] 0x5B [6] 0x5B [5] 0x5B [4] 0x5B [3] 0x5B [2] 0x5B [1] 0x5B [0]
Value 54 0 1 0 1 0 1 0 0

Table 10. Example Of EEPROM For Four Devices Using Two Address Maps

EEPROM Address Address (Hex) EEPROM Data Comments
0 00 0x43 CRC_EN = 0, Address Map = 1, >256 bytes = 0, Device Count[3:0] = 3
1 01 0x00
2 02 0x08 EEPROM Burst Size
3 03 0x00 CRC not used
4 04 0x0B Device 0 Address Location
5 05 0x00 CRC not used
6 06 0x0B Device 1 Address Location
7 07 0x00 CRC not used
8 08 0x30 Device 2 Address Location
9 09 0x00 CRC not used
10 0A 0x30 Device 3 Address Location
11 0B 0x00 Begin Device 0, 1 - Address Offset 3
12 0C 0x00
13 0D 0x04
14 0E 0x07
15 0F 0x00
16 10 0x01 EQ CHB0 = 01
17 11 0xAD VOD CHB0 = 1.2V
18 12 0x00 DEM CHB0 = 0 (0dB)
19 13 0x00 EQ CHB1 = 01
20 14 0x1A VOD CHB1 = 1.2V
21 15 0xD0 DEM CHB1 = 0 (0dB)
22 16 0x00
23 17 0x01 EQ CHB2 = 01
24 18 0xAD VOD CHB2 = 1.2V
25 19 0x00 DEM CHB2 = 0 (0dB)
26 1A 0x00 EQ CHB3 = 01
27 1B 0x1A VOD CHB3 = 1.2V
28 1C 0xD0 DEM CHB3 = 0 (0dB)
29 1D 0x09 Signal Detect Control
30 1E 0x80 Signal Detect Control
31 1F 0x07 EQ CHA0 = 03
32 20 0x5E VOD CHA0 = 111'b
33 21 0x00 DEM CHA0 = 0 (0dB)
34 22 0x00 EQ CHA1 = 03
35 23 0x75 VOD CHA1 = 111'b
36 24 0xE0 DEM CHA1 = 0 (0dB)
37 25 0x00
38 26 0x07 EQ CHA2 = 03
39 27 0x5E VOD CHA2 = 1.4V
40 28 0x00 DEM CHA2 = 0 (0dB)
41 29 0x00 EQ CHA3 = 03
42 2A 0x75 VOD CHA3 = 111'b
43 2B 0xE0 DEM CHA3 = 0 (0dB)
44 2C 0x00
45 2D 0x00
46 2E 0x54
47 2F 0x54 End Device 0, 1 - Address Offset 39
48 30 0x00 Begin Device 2, 3 - Address Offset 3
49 31 0x00
50 32 0x04
51 33 0x07
52 34 0x00
53 35 0x01 EQ CHB0 = 01
54 36 0xAB VOD CHB0 = 1.0V
55 37 0x00 DEM CHB0 = 0 (0dB)
56 38 0x00 EQ CHB1 = 01
57 39 0x1A VOD CHB1 = 1.0V
58 3A 0xB0 DEM CHB1 = 0 (0dB)
59 3B 0x00
60 3C 0x01 EQ CHB2 = 01
61 3D 0xAB VOD CHB2 = 1.0V
62 3E 0x00 DEM CHB2 = 0 (0dB)
63 3F 0x00 EQ CHB3 = 01
64 40 0x1A VOD CHB3 = 1.0V
65 41 0xB0 DEM CHB3 = 0 (0dB)
66 42 0x09 Signal Detect Control
67 43 0x80 Signal Detect Control
68 44 0x03 EQ CHA0 = 01
69 45 0x5E VOD CHA0 = 111'b
70 46 0x00 DEM CHA0 = 0 (0dB)
71 47 0x00 EQ CHA1 = 01
72 48 0x35 VOD CHA1 = 111'b
73 49 0xE0 DEM CHA1 = 0 (0dB)
74 4A 0x00
75 4B 0x03 EQ CHA2 = 01
76 4C 0x5E VOD CHA2 = 111'b
77 4D 0x00 DEM CHA2 = 0 (0dB)
78 4E 0x00 EQ CHA3 = 01
79 4F 0x35 VOD CHA3 = 111'b
80 50 0xE0 DEM CHA3 = 0 (0dB)
81 51 0x00
82 52 0x00
83 53 0x54
84 54 0x54 End Device 2, 3 - Address Offset 39

Note: CRC_EN = 0, Address Map = 1, >256 byte = 0, Device Count[3:0] = 3. Multiple devices can point to the same address map. Maximum EEPROM size is 8 kbits (1024 x 8-bits).

7.7 Register Maps

The System Management Bus interface is compatible to SMBus 2.0 physical layer specification. ENSMB = 1kΩ to VDD to enable SMBus slave mode and allow access to the configuration registers.

The DS125BR401A has the AD[3:0] inputs in SMBus mode. These Terminals are the user set SMBus slave address inputs. The AD[3:0] Terminals have internal pull-down. When left floating or pulled low the AD[3:0] = 0000'b, the device default address byte is B0'h. Based on the SMBus 2.0 specification, the DS125BR401A has a 7-bit slave address. The LSB is set to 0'b (for a WRITE). The device supports up to 16 address byte, which can be set with the AD[3:0] inputs. Below are the 16 addresses.

Table 11. Device Slave Address Bytes

AD[3:0] Settings Address Bytes (HEX)
0000 B0
0001 B2
0010 B4
0011 B6
0100 B8
0101 BA
0110 BC
0111 BE
1000 C0
1001 C2
1010 C4
1011 C6
1100 C8
1101 CA
1110 CC
1111 CE

The SDA, SCL Terminals are 3.3V tolerant, but are not 5V tolerant. External pull-up resistor is required on the SDA. The resistor value can be from 1 kΩ to 5 kΩ depending on the voltage, loading and speed. The SCL may also require an external pull-up resistor and it depends on the Host that drives the bus.

7.7.1 Transfer Of Data Via The SMBus

During normal operation the data on SDA must be stable during the time when SCL is High.

There are three unique states for the SMBus:

START: A High-to-Low transition on SDA while SCL is High indicates a message START condition.

STOP: A Low-to-High transition on SDA while SCL is High indicates a message STOP condition.

IDLE: If SCL and SDA are both High for a time exceeding tBUF from the last detected STOP condition or if they are High for a total exceeding the maximum specification for tHIGH then the bus will transfer to the IDLE state.

7.7.2 SMBus Transactions

The device supports WRITE and READ transactions. See Table 12 for register address, type (Read/Write, Read Only), default value and function information.

7.7.3 Writing a Register

To write a register, the following protocol is used (see SMBus 2.0 specification).

  1. The Host drives a START condition, the 7-bit SMBus address, and a “0” indicating a WRITE.
  2. The Device (Slave) drives the ACK bit (“0”).
  3. The Host drives the 8-bit Register Address.
  4. The Device drives an ACK bit (“0”).
  5. The Host drive the 8-bit data byte.
  6. The Device drives an ACK bit (“0”).
  7. The Host drives a STOP condition.

The WRITE transaction is completed, the bus goes IDLE and communication with other SMBus devices may now occur.

7.7.4 Reading a Register

To read a register, the following protocol is used (see SMBus 2.0 specification).

  1. The Host drives a START condition, the 7-bit SMBus address, and a “0” indicating a WRITE.
  2. The Device (Slave) drives the ACK bit (“0”).
  3. The Host drives the 8-bit Register Address.
  4. The Device drives an ACK bit (“0”).
  5. The Host drives a START condition.
  6. The Host drives the 7-bit SMBus Address, and a “1” indicating a READ.
  7. The Device drives an ACK bit “0”.
  8. The Device drives the 8-bit data value (register contents).
  9. The Host drives a NACK bit “1”indicating end of the READ transfer.
  10. The Host drives a STOP condition.

The READ transaction is completed, the bus goes IDLE and communication with other SMBus devices may now occur.

Table 12 for more information.

Table 12. SMBus Slave Mode Register Map

Address Register Name Bit Field Type Default Description
0x00 Observation 7 Reserved R/W 0x00 Set bit to 0.
6:3 Address Bit
AD[3:0]		 R Observation of AD[3:0] bits
[6]: AD3
[5]: AD2
[4]: AD1
[3]: AD0
2 EEPROM Read Done R 1: Device completed the read from external EEPROM.
1 Reserved R/W Set bit to 0.
0 Reserved R/W Set bit to 0.
0x01 PWDN Channels 7:0 PWDN CHx R/W 0x00 Power Down per Channel
[7]: CH7 – CHA_3
[6]: CH6 – CHA_2
[5]: CH5 – CHA_1
[4]: CH4 – CHA_0
[3]: CH3 – CHB_3
[2]: CH2 – CHB_2
[1]: CH1 – CHB_1
[0]: CH0 – CHB_0
00'h = all channels enabled
FF'h = all channels disabled
Note: override PWDN Terminal.
0x02 Override PWDN 7:1 Reserved R/W 0x00 Set bits to 0.
0 Override PWDN
Terminal		 1: Block PWDN Terminal control
0: Allow PWDN Terminal control
0x04 EQ Limiting 7:0 EQ Control R/W 0x00 CH3 - CH0 EQ Limiting Control
[7]: CH7 – CHA_3 (linear only)
[6]: CH6 – CHA_2 (linear only)
[5]: CH5 – CHA_1 (linear only)
[4]: CH4 – CHA_0 (linear only)
[3]: CH3 – CHB_3
[2]: CH2 – CHB_2
[1]: CH1 – CHB_1
[0]: CH0 – CHB_0
00'h = all channels linear EQ
0F'h = B-channels limiting EQ
Note: These bits do not connect to the A-Channel
0x05 Slave Mode CRC bits 7:0 CRC bits R/W 0x00 CRC bits [7:0]
0x06 Slave Register Control 7:5 Reserved R/W 0x10 Set bits to 0.
4 Reserved Set bit to 1.
3 Register Enable 1: Enables high speed channel control via SMBus registers without CRC
0: Channel control via SMBus registers requires correct CRC in Reg 0x05
Note: In order to change VOD, DEM and EQ of the channels in slave mode without also setting CRC each time, set this bit to 1.
2:0 Reserved Set bits to 0.
0x07 Digital Reset and Control 7 Reserved R/W 0x01 Set bit to 0.
6 Reset Registers Self clearing reset for SMBus registers. Writing a [1] will return register settings to default values.
5 Reset SMBus Master Self clearing reset to SMBus master state machine
4:0 Reserved Set bits to 0 0001'b.
0x08 Override
Terminal Control 		7 Reserved R/W 0x00 Set bit to 0.
6 Override SD_TH 1: Block SD_TH Terminal control
0: Allow SD_TH Terminal control
5 Reserved Set bit to 0.
4 Override IDLE 1: IDLE control by registers
0: IDLE control by signal detect
Note: These bits do not connect to the A-Channel
3 Override RXDET 1: Block RXDET Terminal control
0: Allow RXDET Terminal control
2 Override MODE_B 1: Block MODE_B Terminal control
0: Allow MODE_B Terminal control
1 Reserved Set bit to 0.
0 Reserved Set bit to 0.
0x0A Signal Detect Monitor 7:0 IDLE Status R 0x00 CH7 - CH0 Internal IDLE indicator
[7]: CH7 – CHA_3
[6]: CH6 – CHA_2
[5]: CH5 – CHA_1
[4]: CH4 – CHA_0
[3]: CH3 – CHB_3
[2]: CH2 – CHB_2
[1]: CH1 – CHB_1
[0]: CH0 – CHB_0
0'b = Signal Detected at input
1'b = Signal Detected at input
Note: These bits only function when MODE_B terminal = FLOAT
0x0E CH0 - CHB0
IDLE, RXDET		 7:6 Reserved R/W 0x00 Set bits to 0.
5 IDLE_AUTO 1: Automatic IDLE detect
0: Allow IDLE_SEL control in bit 4
Note: override IDLE control.
4 IDLE_SEL 1: Output is MUTED (electrical idle)
0: Output is ON
Note: override IDLE control.
3:2 RXDET 00: Input is high-z impedance
01: Auto RX-Detect,
outputs test every 12 ms for 600 ms (50 times) then stops; termination is high-z until detection; once detected input termination is 50 Ω
10: Auto RX-Detect,
outputs test every 12 ms until detection occurs; termination is high-z until detection; once detected input termination is 50 Ω
11: Input is 50 Ω
Note: override RXDET Terminal.
1:0 Reserved Set bits to 0.
0x0F CH0 - CHB0
EQ		 7:0 EQ Control R/W 0x2F INB_0 EQ Control - total of 256 levels.
See Table 5.
0x10 CH0 - CHB_0
VOD 		7 Short Circuit Protection R/W 0xAD 1: Enable the short circuit protection
0: Disable the short circuit protection
6 MODE_SEL 1: PCIe Gen 1/2
0: SAS-3 and PCIe Gen 3
Note: override the MODE_B Terminal.
5:3 Reserved Set bits to default value - 101.
2:0 VOD Control OUTB_0 VOD Control
000: 0.7 V
001: 0.8 V
010: 0.9 V
011: 1.0 V
100: 1.1 V
101: 1.2 V (default)
110: 1.3 V
111: 1.4 V
0x11 CH0 - CHB_0
DEM		 7 RXDET STATUS R 0x02 Observation bit for RXDET CH0 - CHB_0.
1: RX = detected
0: RX = not detected
6:5 MODE_DET STATUS R Observation bit for MODE_DET CH0 - CHB_0.
00: GEN1 (2.5G data-rate)
01: GEN2 (5G data-rate)
11: GEN3 (8G+ data-rate)
Note: Only functions when MODE_B Terminal = Automatic
4:3 Reserved R/W Set bits to 0.
2:0 DEM Control R/W OUTB_0 DEM Control
000: 0 dB
001: –1.5 dB
010: –3.5 dB (default)
011: –5 dB
100: –6 dB
101: –8 dB
110: –9 dB
111: –12 dB
0x12 CH0 - CHB_0
SD Threshold		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 IDLE tha Assert threshold (1010 pattern 12 Gbps)
00 = 50 mVp-p (default)
01 = 40 mVp-p
10 = 75 mVp-p
11 = 58 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
1:0 IDLE thd De-assert threshold (1010 pattern 12 Gbps)
00 = 37 mVp-p (default)
01 = 22 mVp-p
10 = 55 mVp-p
11 = 45 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
0x15 CH1 - CHB_1
IDLE, RXDET		 7:6 Reserved R/W 0x00 Set bits to 0.
5 IDLE_AUTO 1: Automatic IDLE detect
0: Allow IDLE_SEL control in bit 4
Note: override IDLE control.
4 IDLE_SEL 1: Output is MUTED (electrical idle)
0: Output is ON
Note: override IDLE control.
3:2 RXDET 00: Input is high-z impedance
01: Auto RX-Detect,
outputs test every 12 ms for 600 ms (50 times) then stops; termination is high-z until detection; once detected input termination is 50 Ω
10: Auto RX-Detect,
outputs test every 12 ms until detection occurs; termination is high-z until detection; once detected input termination is 50 Ω
11: Input is 50 Ω
Note: override RXDET Terminal.
1:0 Reserved Set bits to 0.
0x16 CH1 - CHB_1
EQ		 7:0 EQ Control R/W 0x2F INB_1 EQ Control - total of 256 levels.
See Table 5.
0x17 CH1 - CHB_1
VOD 		7 Short Circuit Protection R/W 0xAD 1: Enable the short circuit protection
0: Disable the short circuit protection
6 MODE_SEL 1: Gen 1/2,
0: SAS-3 and PCIe Gen 3
Note: override the MODE_B Terminal.
5:3 Reserved Set bits to default value - 101.
2:0 VOD Control OUTB_1 VOD Control
000: 0.7 V
001: 0.8 V
010: 0.9 V
011: 1.0 V
100: 1.1 V
101: 1.2 V (default)
110: 1.3 V
111: 1.4 V
0x18 CH1 - CHB_1
DEM		 7 RXDET STATUS R 0x02 Observation bit for RXDET CH1 - CHB_1.
1: RX = detected
0: RX = not detected
6:5 MODE_DET STATUS R Observation bit for MODE_DET CH1 - CHB_1.
00: GEN1 (2.5G data-rate)
01: GEN2 (5G data-rate)
11: GEN3 (8G+ data-rate)
Note: Only functions when MODE_B Terminal = Automatic
4:3 Reserved R/W Set bits to 0.
2:0 DEM Control R/W OUTB_1 DEM Control
000: 0 dB
001: –1.5 dB
010: –3.5 dB (default)
011: –5 dB
100: –6 dB
101: –8 dB
110: –9 dB
111: –12 dB
0x19 CH1 - CHB_1
SD Threshold		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 IDLE tha Assert threshold (1010 pattern 12 Gbps)
00 = 50 mVp-p (default)
01 = 40 mVp-p
10 = 75 mVp-p
11 = 58 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
1:0 IDLE thd De-assert threshold (1010 pattern 12 Gbps)
00 = 37 mVp-p (default)
01 = 22 mVp-p
10 = 55 mVp-p
11 = 45 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
0x1C CH2 - CHB_2
IDLE, RXDET		 7:6 Reserved R/W 0x00 Set bits to 0.
5 IDLE_AUTO 1: Automatic IDLE detect
0: Allow IDLE_SEL control in bit 4
Note: override IDLE control.
4 IDLE_SEL 1: Output is MUTED (electrical idle)
0: Output is ON
Note: override IDLE control.
3:2 RXDET 00: Input is high-z impedance
01: Auto RX-Detect,
outputs test every 12 ms for 600 ms (50 times) then stops; termination is high-z until detection; once detected input termination is 50 Ω
10: Auto RX-Detect,
outputs test every 12 ms until detection occurs; termination is high-z until detection; once detected input termination is 50 Ω
11: Input is 50 Ω
Note: override RXDET Terminal.
1:0 Reserved Set bits to 0.
0x1D CH2 - CHB2
EQ		 7:0 EQ Control R/W 0x2F INB_2 EQ Control - total of 256 levels.
See Table 5.
0x1E CH2 - CHB2
VOD 		7 Short Circuit Protection R/W 0xAD 1: Enable the short circuit protection
0: Disable the short circuit protection
6 MODE_SEL 1: Gen 1/2,
0: SAS-3 and PCIe Gen 3
Note: override the MODE_B Terminal.
5:3 Reserved Set bits to default value - 101.
2:0 VOD Control OUTB_2 VOD Control
000: 0.7 V
001: 0.8 V
010: 0.9 V
011: 1.0 V
100: 1.1 V
101: 1.2 V (default)
110: 1.3 V
111: 1.4 V
0x1F CH2 - CHB_2
DEM		 7 RXDET STATUS R 0x02 Observation bit for RXDET CH2 - CHB_2.
1: RX = detected
0: RX = not detected
6:5 MODE_DET STATUS R Observation bit for MODE_DET CH2 - CHB_2.
00: GEN1 (2.5G data-rate)
01: GEN2 (5G data-rate)
11: GEN3 (8G+ data-rate)
Note: Only functions when MODE_B Terminal = Automatic
4:3 Reserved R/W Set bits to 0.
2:0 DEM Control R/W OUTB_2 DEM Control
000: 0 dB
001: –1.5 dB
010: –3.5 dB (default)
011: –5 dB
100: –6 dB
101: –8 dB
110: –9 dB
111: –12 dB
0x20 CH2 - CHB_2
SD Threshold		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 IDLE tha Assert threshold (1010 pattern 12 Gbps)
00 = 50 mVp-p (default)
01 = 40 mVp-p
10 = 75 mVp-p
11 = 58 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
1:0 IDLE thd De-assert threshold (1010 pattern 12 Gbps)
00 = 37 mVp-p (default)
01 = 22 mVp-p
10 = 55 mVp-p
11 = 45 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
0x23 CH3 - CHB_3
IDLE, RXDET		 7:6 Reserved R/W 0x00 Set bits to 0.
5 IDLE_AUTO 1: Automatic IDLE detect
0: Allow IDLE_SEL control in bit 4
Note: override IDLE control.
4 IDLE_SEL 1: Output is MUTED (electrical idle)
0: Output is ON
Note: override IDLE control.
3:2 RXDET 00: Input is high-z impedance
01: Auto RX-Detect,
outputs test every 12 ms for 600 ms (50 times) then stops; termination is high-z until detection; once detected input termination is 50 Ω
10: Auto RX-Detect,
outputs test every 12 ms until detection occurs; termination is high-z until detection; once detected input termination is 50 Ω
11: Input is 50 Ω
Note: override RXDET Terminal.
1:0 Reserved Set bits to 0.
0x24 CH3 - CHB_3
EQ		 7:0 EQ Control R/W 0x2F INB_3 EQ Control - total of 256 levels.
See Table 5.
0x25 CH3 - CHB_3
VOD 		7 Short Circuit Protection R/W 0xAD 1: Enable the short circuit protection
0: Disable the short circuit protection
6 MODE_SEL 1: Gen 1/2,
0: SAS-3 and PCIe Gen 3
Note: override the MODE_B Terminal.
5:3 Reserved Set bits to default value - 101.
2:0 VOD Control OUTB_3 VOD Control
000: 0.7 V
001: 0.8 V
010: 0.9 V
011: 1.0 V
100: 1.1 V
101: 1.2 V (default)
110: 1.3 V
111: 1.4 V
0x26 CH3 - CHB_3
DEM		 7 RXDET STATUS R 0x02 Observation bit for RXDET CH3 - CHB_3.
1: RX = detected
0: RX = not detected
6:5 MODE_DET STATUS R Observation bit for MODE_DET CH3 - CHB_3.
00: GEN1 (2.5G data-rate)
01: GEN2 (5G data-rate)
11: GEN3 (8G+ data-rate)
Note: Only functions when MODE_B Terminal = Automatic
4:3 Reserved R/W Set bits to 0.
2:0 DEM Control R/W OUTB_3 DEM Control
000: 0 dB
001: –1.5 dB
010: –3.5 dB (default)
011: –5 dB
100: –6 dB
101: –8 dB
110: –9 dB
111: –12 dB
0x27 CH3 - CHB_3
SD Threshold		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 IDLE tha Assert threshold (1010 pattern 12 Gbps)
00 = 50 mVp-p (default)
01 = 40 mVp-p
10 = 75 mVp-p
11 = 58 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
1:0 IDLE thd De-assert threshold (1010 pattern 12 Gbps)
00 = 37 mVp-p (default)
01 = 22 mVp-p
10 = 55 mVp-p
11 = 45 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
0x28 Signal Detect Control 7:6 Reserved R/W 0x0C Set bits to 0.
5:4 High IDLE Enable higher range of Signal Detect Thresholds
[5]: CH0 - CH3
[4]: CH4 - CH7
3:2 Fast IDLE Enable Fast OOB response
[3]: CH0 - CH3
[2]: CH4 - CH7
1:0 Reduced SD Gain Enable reduced Signal Detect Gain
[1]: CH0 - CH3
[0]: CH4 - CH7
0x2B CH4 - CHA_0
RXDET		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 RXDET 00: Input is high-z impedance
01: Auto RX-Detect,
outputs test every 12 ms for 600 ms (50 times) then stops; termination is high-z until detection; once detected input termination is 50 Ω
10: Auto RX-Detect,
outputs test every 12 ms until detection occurs; termination is high-z until detection; once detected input termination is 50 Ω
11: Input is 50 Ω
Note: override RXDET Terminal.
1:0 Reserved Set bits to 0.
0x2C CH4 - CHA_0
EQ		 7:0 EQ Control R/W 0x2F INA_0 EQ Control - total of 4 levels.
See Table 6.
0x2D CH4 - CHA_0
VOD 		7 Short Circuit Protection R/W 0xAD 1: Enable the short circuit protection
0: Disable the short circuit protection
6 Reserved Set bit to 0.
5:3 Reserved Set bits to default value - 101.
2:0 VOD Control OUTA_0 VOD Control
000: 0.65
001: 0.70
010: 0.78
011: 0.83
100: 0.88
101: 0.91 (Default)
110: 1.00
111: 1.05 (Recommended for SAS)
0x2E CH4 - CHA_0
DEM		 7 RXDET STATUS R 0x02 Observation bit for RXDET CH4 - CHA_0.
1: RX = detected
0: RX = not detected
6:5 MODE_DET STATUS R Observation bit for MODE_DET CH4 - CHA_0.
00: GEN1 (2.5G data-rate)
01: GEN2 (5G data-rate)
11: GEN3 (8G+ data-rate)
Note: Only functions when MODE_B Terminal = Automatic
4:3 Reserved R/W Set bits to 0.
2:0 DEM Control R/W OUTA_0 DEM Control (010'b Default)
This control does not provide a DEM function for A-Channel outputs. Based on system interoperability testing it is recommended to set these bits to 000'b for SAS and PCIe applications.
0x2F CH4 - CHA_0
SD Threshold		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 IDLE tha Assert threshold (1010 pattern 12 Gbps)
00 = 50 mVp-p (default)
01 = 40 mVp-p
10 = 75 mVp-p
11 = 58 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
1:0 IDLE thd De-assert threshold (1010 pattern 12 Gbps)
00 = 37 mVp-p (default)
01 = 22 mVp-p
10 = 55 mVp-p
11 = 45 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
0x32 CH5 - CHA_1
RXDET		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 RXDET 00: Input is high-z impedance
01: Auto RX-Detect,
outputs test every 12 ms for 600 ms (50 times) then stops; termination is high-z until detection; once detected input termination is 50 Ω
10: Auto RX-Detect,
outputs test every 12 ms until detection occurs; termination is high-z until detection; once detected input termination is 50 Ω
11: Input is 50 Ω
Note: override RXDET Terminal.
1:0 Reserved Set bits to 0.
0x33 CH5 - CHA_1
EQ		 7:0 EQ Control R/W 0x2F INA_1 EQ Control - total of 4 levels.
See Table 6.
0x34 CH5 - CHA_1
VOD 		7 Short Circuit Protection R/W 0xAD 1: Enable the short circuit protection
0: Disable the short circuit protection
6 Reserved Set bit to 0.
5:3 Reserved Set bits to default value - 101.
2:0 VOD Control OUTA_1 VOD Control
000: 0.65
001: 0.70
010: 0.78
011: 0.83
100: 0.88
101: 0.91 (Default)
110: 1.00
111: 1.05 (Recommended for SAS)
0x35 CH5 - CHA1
DEM		 7 RXDET STATUS R 0x02 Observation bit for RXDET CH5 - CHA_1.
1: RX = detected
0: RX = not detected
6:5 MODE_DET STATUS R Observation bit for MODE_DET CH5 - CHA_1.
00: GEN1 (2.5G data-rate)
01: GEN2 (5G data-rate)
11: GEN3 (8G+ data-rate)
Note: Only functions when MODE_B Terminal = Automatic
4:3 Reserved R/W Set bits to 0.
2:0 DEM Control R/W OUTA_1 DEM Control (010'b Default)
This control does not provide a DEM function for A-Channel outputs. Based on system interoperability testing it is recommended to set these bits to 000'b for SAS and PCIe applications.
0x36 CH5 - CHA_1
SD Threshold		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 IDLE tha Assert threshold (1010 pattern 12 Gbps)
00 = 50 mVp-p (default)
01 = 40 mVp-p
10 = 75 mVp-p
11 = 58 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
1:0 IDLE thd De-assert threshold (1010 pattern 12 Gbps)
00 = 37 mVp-p (default)
01 = 22 mVp-p
10 = 55 mVp-p
11 = 45 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
0x39 CH6 - CHA_2
RXDET		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 RXDET 00: Input is high-z impedance
01: Auto RX-Detect,
outputs test every 12 ms for 600 ms (50 times) then stops; termination is high-z until detection; once detected input termination is 50 Ω
10: Auto RX-Detect,
outputs test every 12 ms until detection occurs; termination is high-z until detection; once detected input termination is 50 Ω
11: Input is 50 Ω
Note: override RXDET Terminal.
1:0 Reserved Set bits to 0.
0x3A CH6 - CHA_2
EQ		 7:0 EQ Control R/W 0x2F INA_2 EQ Control - total of 4 levels.
See Table 6.
0x3B CH6 - CHA_2
VOD 		7 Short Circuit Protection R/W 0xAD 1: Enable the short circuit protection
0: Disable the short circuit protection
6 Reserved set bit to 0.
5:3 Reserved Set bits to default value - 101.
2:0 VOD Control OUTA_2 VOD Control: VOD / VID Ratio
000: 0.65
001: 0.70
010: 0.78
011: 0.83
100: 0.88
101: 0.91 (Default)
110: 1.00
111: 1.05 (Recommended for SAS)
0x3C CH6 - CHA_2
DEM		 7 RXDET STATUS R 0x02 Observation bit for RXDET CH6 - CHA_2.
1: RX = detected
0: RX = not detected
6:5 MODE_DET STATUS R Observation bit for MODE_DET CH6 - CHA_2.
00: GEN1 (2.5G data-rate)
01: GEN2 (5G data-rate)
11: GEN3 (8G+ data-rate)
Note: Only functions when MODE_B Terminal = Automatic
4:3 Reserved R/W Set bits to 0.
2:0 DEM Control R/W OUTA_2 DEM Control (010'b Default)
This control does not provide a DEM function for A-Channel outputs. Based on system interoperability testing it is recommended to set these bits to 000'b for SAS and PCIe applications.
0x3D CH6 - CHA_2
SD Threshold		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 IDLE tha Assert threshold (1010 pattern 12 Gbps)
00 = 50 mVp-p (default)
01 = 40 mVp-p
10 = 75 mVp-p
11 = 58 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
1:0 IDLE thd De-assert threshold (1010 pattern 12 Gbps)
00 = 37 mVp-p (default)
01 = 22 mVp-p
10 = 55 mVp-p
11 = 45 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
0x40 CH7 - CHA_3
RXDET		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 RXDET 00: Input is high-z impedance
01: Auto RX-Detect,
outputs test every 12 ms for 600 ms (50 times) then stops; termination is high-z until detection; once detected input termination is 50 Ω
10: Auto RX-Detect,
outputs test every 12 ms until detection occurs; termination is high-z until detection; once detected input termination is 50 Ω
11: Input is 50 Ω
Note: override RXDET Terminal.
1:0 Reserved Set bits to 0.
0x41 CH7 - CHA_3
EQ		 7:0 EQ Control R/W 0x2F INA_3 EQ Control - total of 4 levels.
See Table 6.
0x42 CH7 - CHA_3
VOD 		7 Short Circuit Protection R/W 0xAD 1: Enable the short circuit protection
0: Disable the short circuit protection
6 Reserved Set bit to 0.
5:3 Reserved Set bits to default value - 101.
2:0 VOD Control OUTA_3 VOD Control: VOD / VID Ratio
000: 0.65
001: 0.70
010: 0.78
011: 0.83
100: 0.88
101: 0.91 (Default)
110: 1.00
111: 1.05 (Recommended for SAS)
0x43 CH7 - CHA_3
DEM		 7 RXDET STATUS R 0x02 Observation bit for RXDET CH7 - CHA3.
1: RX = detected
0: RX = not detected
6:5 MODE_DET STATUS R Observation bit for MODE_DET CH7 - CHA3.
00: GEN1 (2.5G data-rate)
01: GEN2 (5G data-rate)
11: GEN3 (8G+ data-rate)
Note: Only functions when MODE_B Terminal = Automatic
4:3 Reserved R/W Set bits to 0.
2:0 DEM Control R/W OUTA_3 DEM Control (010'b Default)
This control does not provide a DEM function for A-Channel outputs. Based on system interoperability testing it is recommended to set these bits to 000'b for SAS and PCIe applications.
0x44 CH7 - CHA3
SD Threshold		 7:4 Reserved R/W 0x00 Set bits to 0.
3:2 IDLE tha Assert threshold (1010 pattern 12 Gbps)
00 = 50 mVp-p (default)
01 = 40 mVp-p
10 = 75 mVp-p
11 = 58 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
1:0 IDLE thd De-assert threshold (1010 pattern 12 Gbps)
00 = 37 mVp-p (default)
01 = 22 mVp-p
10 = 55 mVp-p
11 = 45 mVp-p
Note: override the SD_TH Terminal using 0x08[6].
0x51 Device ID 7:5 VERSION R 0x84 100'b
4:0 ID 00100'b