SNLS374D May   1998  – January 2015 DS8921

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Electrical Characteristics
    5. 6.5 Receiver Switching Characteristics
    6. 6.6 Driver Switching Characteristics: Single-Ended Characteristics
    7. 6.7 Driver Switching Characteristics: Differential Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 AC Test Circuits and Switching Diagrams
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8 Detailed Description

8.1 Overview

The DS8921x devices are each a differential line driver and receiver pair in a single package. The devices are designed specifically for ST506, ST412, and ESDI disk drive standards, as well as RS-422 interface applications. The DS8921 and DS8921A are rated at a commercial temperature range of 0°C to 70°C, whereas the DS8921AT is rated at an extended temperature range of -40°C to +85°C.

8.2 Functional Block Diagram

DS8921_BlockDiagram.gif

8.3 Feature Description

The DS8921x devices each contain a differential driver and receiver.

The driver converts a TTL or CMOS input to complementary outputs that provide differential drive to a twisted-pair or parallel wire transmission line. The receiver converts the differential signals at its input pins to a TTL output. The receiver offers an input sensitivity of ±200 mV and supports a common-mode input voltage of ±7 V.

8.4 Device Functional Modes

Table 1. Function Table

RECEIVER DRIVER
INPUT OUTPUT INPUT OUTPUT
RI+, RI- RO DI DO+ DO-
VID(1) ≥ VTH (MAX) 1 1 1 0
VID(1) ≤ VTH (MIN) 0 0 0 1
Open 1
(1) VID is the input differential voltage between RI+ and RI–.