SNLS544B September   2016  – October 2019 DS280BR820

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 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 Electrical Characteristics – Serial Management Bus Interface
    7. 6.7 Timing Requirements – Serial Management Bus Interface
    8. 6.8 Typical Characteristics
  7. 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 AC-Coupled Receiver Inputs
      3. 7.3.3 Signal Detect
      4. 7.3.4 2-Stage CTLE
      5. 7.3.5 Driver DC Gain Control
      6. 7.3.6 FIR Filter (Limiting Mode)
      7. 7.3.7 Configurable SMBus Address
    4. 7.4 Device Functional Modes
      1. 7.4.1 SMBus Slave Mode Configuration
      2. 7.4.2 SMBus Master Mode Configuration (EEPROM Self Load)
    5. 7.5 Programming
      1. 7.5.1 Transfer of Data with the SMBus Interface
    6. 7.6 Register Maps
      1. 7.6.1 Register Types: Global, Shared, and Channel
      2. 7.6.2 Global Registers: Channel Selection and ID Information
        1. Table 2. Global Register Map
      3. 7.6.3 Shared Registers
        1. Table 3. Shared Register Map
      4. 7.6.4 Channel Registers
        1. Table 4. Channel Register Map
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Backplane and Mid-Plane Reach Extension
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
      2. 8.2.2 Front-Port Applications
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
        1. 8.2.3.1 Pattern Generator Characteristics
        2. 8.2.3.2 Equalizing Moderate Pre-Channel Loss
        3. 8.2.3.3 Equalizing High Pre-Channel Loss
        4. 8.2.3.4 Equalizing High Pre-Channel Loss and Moderate Post-Channel Loss
        5. 8.2.3.5 Output in FIR Limiting Mode with 16T Pattern
    3. 8.3 Initialization Set Up
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
      1. 10.2.1 Stripline Example
      2. 10.2.2 Microstrip Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary

Package Options

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

7.5.1 Transfer of Data with the SMBus Interface

The System Management Bus (SMBus) is a two-wire serial interface through which a master can communicate with various system components. Slave devices are identified by a unique device address. The two-wire serial interface consists of SDC and SDA signals. SDC is a clock output from the master to all of the slave devices on the bus. SDA is a bidirectional data signal between the master and slave devices. The DS280BR820 SMBus SDC and SDA signals are open drain and require external pull-up resistors.

Start and Stop Conditions:

The master generates Start and Stop conditions at the beginning and end of each transaction:

  • Start: HIGH to LOW transition (falling edge) of SDA while SDC is HIGH.
  • Stop: LOW to HIGH transition (rising edge) of SDA while SDC is HIGH.

The master generates 9 clock pulses for each byte transfer. The 9th clock pulse constitutes the acknowledge (ACK) cycle. The transmitter releases SDA to allow the receiver to send the ACK signal. An ACK is when the device pulls SDA LOW, while a NACK (no acknowledge) is recorded if the line remains HIGH.

Writing data from a master to a slave consists of three parts:

  • The master begins with a start condition followed by the slave device address with the R/W bit cleared.
  • The master sends the 8-bit register address that will be written.
  • The master sends the data byte to write for the selected register address. The register address pointer will then increment, so the master can send the data byte for the subsequent register without re-addressing the device, if desired. The final data byte to write should be followed by a stop condition.

SMBus read operations consist of four parts:

  • The master initiates the read cycle with start condition followed by slave device address with the R/W bit cleared.
  • The master sends the 8-bit register address that will be read.
  • After acknowledgment from the slave, the master initiates a re-start condition.
  • The slave device address is resent followed with R/W bit set.
  • After acknowledgment from the slave, the data is read back from the slave to the master. The last ACK is HIGH if there are no more bytes to read.