SCES635B JULY   2005  – April 2015 SN74LVCH16T245

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics
    6. 7.6  Switching Characteristics for VCCA = 1.8 V ±0.15 V
    7. 7.7  Switching Characteristics for VCCA = 2.5 V ±0.2 V
    8. 7.8  Switching Characteristics for VCCA = 3.3 V ±0.3 V
    9. 7.9  Switching Characteristics for VCCA = 5 V ±0.5 V
    10. 7.10 Operating Characteristics
    11. 7.11 Typical Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Fully Configurable Dual-Rail Design Allows Each Port to Operate Over the Full 1.65-V to 5.5-V Power-Supply Range
      2. 9.3.2 Support High-Speed Translation
      3. 9.3.3 Partial-Power-Down Mode Operation
      4. 9.3.4 VCC Isolation
      5. 9.3.5 Bus Hold on Data Inputs
    4. 9.4 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Enable Times
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curve
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Trademarks
    3. 13.3 Electrostatic Discharge Caution
    4. 13.4 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

9 Detailed Description

9.1 Overview

The SN74LVCH16T245 is a 16-bit, dual-supply noninverting bidirectional voltage level translation. Pins AX and control pins (DIR and OE) are supported by VCCA and pins BX are supported by VCCB. The A port is able to accept I/O voltages ranging from 1.65 V to 5.5 V, while the B port can accept I/O voltages from 1.65 V to 5.5 V. A high on DIR allows data transmission from A to B and a low on DIR allows data transmission from B to A when OE is set to low. When OE is set to high, both A and B are in the high-impedance state.

This device has Active bus-hold circuitry that holds unused or undriven inputs at a valid logic state. This device is fully specified for partial-power-down applications using off output current (Ioff).

The VCC isolation feature ensures that if either VCC input is at GND, both ports are put in a high-impedance state.

9.2 Functional Block Diagram

SN74LVCH16T245 ld2_ces635.gif

9.3 Feature Description

9.3.1 Fully Configurable Dual-Rail Design Allows Each Port to Operate Over the Full 1.65-V to 5.5-V Power-Supply Range

Both VCCA and VCCB can be supplied at any voltage from 1.65 V to 5.5 V making the device suitable for translating between any of the low voltage nodes (1.8-V, 2.5-V, and 3.3-V).

9.3.2 Support High-Speed Translation

SN74LVCH16T245 can support high data rate application. Data rates can be calculated form the maximum propagation delay. This is also dependant on the output load. For example, for a 3.3-V to 5-V conversion, the maximum frequency is 200 MHz.

9.3.3 Partial-Power-Down Mode Operation

This device is fully specified for partial-power-down applications using off output current (Ioff). Ioff will prevent backflow current by disabling I/O output circuits when device is in partial power-down mode.

9.3.4 VCC Isolation

The VCC isolation feature ensures that if either VCCA or VCCB are at GND, both ports will be in a high-impedance state (IOZ shown in Electrical Characteristics). This prevents false logic levels from being presented to either bus.

9.3.5 Bus Hold on Data Inputs

Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use of pullup or pulldown resistors with the bus-hold circuitry is not recommended.

9.4 Device Functional Modes

The SN74LVCH16T245 is a voltage level translator that can operate from 1.65 V to 5.5 V (VCCA) and 1.65 V to 5.5 V (VCCB). The signal translation between 1.65 V and 5.5 V requires direction control and output enable control. When OE is low and DIR is high, data transmission is from A to B. When OE is low and DIR is low, data transmission is from B to A. When OE is high, both output ports will be high-impedance.

Table 1. Function Table (Each Transceiver)(1)

CONTROL INPUTS OUTPUT CIRCUITS OPERATION
OE DIR A PORT B PORT
L L Enabled Hi-Z B data to A bus
L H Hi-Z Enabled A data to B bus
H X Hi-Z Hi-Z Isolation
(1) Input circuits of the data I/Os are always active.