JAJSBK7H January   2012  – February 2018 DS125DF410


  1. 特長
  2. アプリケーション
  3. 概要
    1.     代表的なアプリケーションの図
  4. 改訂履歴
  5. Pin Configuration and Functions
    1.     Pin Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Device Data Path Operation
      2. 7.3.2 Signal Detect
      3. 7.3.3 CTLE
      4. 7.3.4 DFE
      5. 7.3.5 Clock and Data Recovery
      6. 7.3.6 Output Driver
      7. 7.3.7 Device Configuration
        1. Rate and Subrate Setting
    4. 7.4 Device Functional Modes
      1. 7.4.1 SMBus Master Mode and SMBus Slave Mode
      2. 7.4.2 Address Lines <ADDR_[3:0]>
      3. 7.4.3 SDA and SDC
      4. 7.4.4 Standards-Based Modes
        1. Ref_mode 3 Mode (Reference Clock Required)
        2. False Lock Detector Setting
        3. Reference Clock In
        4. Reference Clock Out
        5. Driver Output Voltage
        6. Driver Output De-Emphasis
        7. Driver Output Rise/Fall Time
        8. INT
        9. LOCK_3, LOCK_2, LOCK_1, and LOCK_0
    5. 7.5 Programming
      1. 7.5.1  SMBus Strap Observation
      2. 7.5.2  Device Revision and Device ID
      3. 7.5.3  Control/Shared Register Reset
      4. 7.5.4  Interrupt Channel Flag Bits
      5. 7.5.5  SMBus Master Mode Control Bits
      6. 7.5.6  Resetting Individual Channels of the Retimer
      7. 7.5.7  Interrupt Status
      8. 7.5.8  Overriding the CTLE Boost Setting
      9. 7.5.9  Overriding the VCO Search Values
      10. 7.5.10 Overriding the Output Multiplexer
      11. 7.5.11 Overriding the VCO Divider Selection
      12. 7.5.12 Using the PRBS Generator
      13. 7.5.13 Using the Internal Eye Opening Monitor
      14. 7.5.14 Overriding the DFE Tap Weights and Polarities
      15. 7.5.15 Enabling Slow Rise/Fall Time on the Output Driver
      16. 7.5.16 Inverting the Output Polarity
      17. 7.5.17 Overriding the Figure of Merit for Adaptation
      18. 7.5.18 Setting the Rate and Subrate for Lock Acquisition
      19. 7.5.19 Setting the Adaptation/Lock Mode
      20. 7.5.20 Initiating Adaptation
      21. 7.5.21 Setting the Reference Enable Mode
      22. 7.5.22 Overriding the CTLE Settings Used for CTLE Adaptation
      23. 7.5.23 Setting the Output Differential Voltage
      24. 7.5.24 Setting the Output De-Emphasis Setting
    6. 7.6 Register Maps
      1. 7.6.1 Register Information
      2. 7.6.2 Bit Fields in the Register Set
      3. 7.6.3 Writing to and Reading from the Control/Shared Registers
      4. 7.6.4 Channel Select Register
      5. 7.6.5 Reading to and Writing from the Channel Registers
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11デバイスおよびドキュメントのサポート
    1. 11.1 ドキュメントのサポート
      1. 11.1.1 関連資料
    2. 11.2 商標
    3. 11.3 静電気放電に関する注意事項
    4. 11.4 Glossary
  12. 12メカニカル、パッケージ、および注文情報



SMBus Master Mode Control Bits

Register 0x04, bits 5 and 4 and register 0x05, bits 7 and 4

Register 0x04, bit 5, can be used to reset the SMBus master mode. This bit should not be set if the DS125DF410 is in SMBus slave mode. This is an undefined condition.

When this bit is set, if the EN_SMB pin is floating (meaning that the DS125DF410 is in SMBus master mode), then the DS125DF410 will read the contents of the external EEPROM when the READ_EN pin is pulled low. This bit is not self-clearing, so it should be cleared after it is set.

When the DS125DF410 EN_SMB pin is floating (meaning that the DS125DF410 is in SMBus master mode), it will read from its external EEPROM when its READ_EN pin goes low. After the EEPROM read operation is complete, register 0x05, bit 4 will be set. Alternatively, the DS125DF410 will read from its external EEPROM when triggered by register 0x04, bit 4, as described below.

When register 0x04, bit 4, is set, the DS125DF410 reads its configuration from an external EEPROM over the SMBus immediately. When this bit is set, the DS125DF410 does not wait until the READ_EN pin is pulled low to read from the EEPROM. This EEPROM read occurs whether the DS125DF410 is in SMBus master mode or not. If the read from the EEPROM is not successful, for example because there is no EEPROM present, then the DS125DF410 may hang up and a power-up reset may be necessary to return it to proper operation. You should only set this bit if you know that the EEPROM is present and properly configured.

If the EEPROM read has already completed, then setting register 0x04, bit 4, will not have any effect. To cause the DS125DF410 to read from the EEPROM again it is necessary to set bit 5 of register 0x04, resetting the SMBus master mode. If the DS125DF410 is not in SMBus master mode, do not set this bit. After setting this bit, it should be cleared before further SMBus operations.

After SMBus master mode has been reset, the EEPROM read may be initiated either by pulling the READ_EN pin low or by then setting register 0x04, bit 4.

Register 0x05, bit 7, disables SMBus master mode. This prevents the DS125DF410 from trying to take command of the SMBus to read from the external EEPROM. Obviously this bit will have no effect if the EEPROM read has already taken place. It also has no effect if an EEPROM read is currently in progress. The only situations in which disabling EEPROM master mode read is valid are (1) when the DS125DF410 is in SMBus master mode, but the READ_EN pin has not yet gone low, and (2) when register 0x04, bit 5, has been used to reset SMBus master mode but the EEPROM read operation has not yet occurred.

Do not set this bit and bit 4 of register 0x04 simultaneously. This is an undefined condition and can cause the DS125DF410 to hang up.