SN74AXCH1T45DCKR

SN74AXCH1T45 ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 具有可配置电压转换、三态输出和总线保持输入的 SN74AXCH1T45 1 位双电源总线收发器 1 特性 • 完全可配置的双电源轨设计可允许各个端口在 0.65V 至 3.6V 的电源电压范围内运行 • 工作温度：–40°C 至 +125°C • 无干扰电源定序 • 总线保持数据输入消除了对外部上拉或下拉电阻的 需求 • 最大静态电流 (ICCA + ICCB) 为 10µA（最高 85°C） 和 16µA（最高 125°C） • 从 1.8V 转换到 3.3 V 时，支持高达 500Mbps 的转 换速率 • VCC 隔离特性 – 如果任何一个 VCC 输入低于 100mV，则所有 I/O 输出均禁用且处于高阻抗状态 • Ioff 支持局部关断模式运行 • 闩锁性能超过 100mA，符合 JESD 78 II 类规范的 要求 • ESD 保护性能超过 JESD 22 规范要求 – 8000V 人体放电模型 – 1000V 充电器件模型 2 应用 • • • • • • 个人电子产品 企业与通信 无线基础设施 楼宇自动化 电子销售终端 企业级固态硬盘 DIR 引脚决定信号传播的方向。DIR 引脚配置为高电平 时，信号转换由端口 A 流向端口 B。DIR 配置为低电 平时，则由端口 B 流向端口 A。DIR 引脚以 VCCA 为基 准，这意味着它的逻辑高电平和逻辑低电平阈值跟踪 VCCA 电压。 有源总线保持电路会将未使用或未驱动的输入保持在有 效逻辑状态。不建议在总线保持电路上使用上拉或下拉 电阻器。如果 VCCA 或 VCCB 连上电源，则总线保持电 路分别在 A 端口或 B 端口上始终保持工作状态，与方 向控制引脚的状态无关。 该器件完全符合使用 Ioff 电流的部分断电应用的规范要 求。当器件断电时，Ioff 保护电路可确保不从输入、输 出或偏置到特定电压的组合 I/O 获取多余电流，也不向 其提供多余电流。 VCC 隔离特性可确保当 VCCA 或 VCCB 低于 100mV 时，I/O 端口均禁用其输出并进入高阻态。 无干扰电源时序使电源轨能以任何顺序打开或关断，从 而提供强大的电源时序性能。 器件信息 封装(1) 封装尺寸（标称值） SN74AXCH1T45DBV SOT-23 (6) 2.90mm × 1.60mm SN74AXCH1T45DCK SC70 (6) 2.00mm × 1.25mm SN74AXCH1T45DTQ X2SON (6) 1.00mm x 0.80mm SN74AXCH1T45DRY SON (6) 1.40mm x 1.00mm 器件型号 (1) 如需了解所有可用封装，请参阅数据表末尾的可订购产品附 录。 3 说明 SN74AXCH1T45 是一款采用两个独立可配置电源轨的 单比特位同相总线收发器。VCCA 和 VCCB 电源电压低 至 0.65V 时，该器件可正常工作。A 端口用于跟踪 VCCA ，该端口可支持 0.65V 至 3.6V 范围内的任何电 源 电 压 。 B 端 口 用 于 跟 踪 VCCB ， 该 端 口 也 可 支 持 0.65V 至 3.6V 范 围 内 的 任 何 电 源 电 压 。 此 外 ， SN74AXCH1T45 还与单电源系统兼容。 VCCA VCCB DIR Bus-Hold B A Bus-Hold 功能方框图 本文档旨在为方便起见，提供有关 TI 产品中文版本的信息，以确认产品的概要。有关适用的官方英文版本的最新信息，请访问 www.ti.com，其内容始终优先。TI 不保证翻译的准确性和有效性。在实际设计之前，请务必参考最新版本的英文版本。 English Data Sheet: SCES883 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 Table of Contents 1 特性................................................................................... 1 2 应用................................................................................... 1 3 说明................................................................................... 1 4 Revision History.............................................................. 2 5 Pin Configuration and Functions...................................3 6 Specifications.................................................................. 4 6.1 Absolute Maximum Ratings........................................ 4 6.2 ESD Ratings............................................................... 4 6.3 Recommended Operating Conditions.........................5 6.4 Thermal Information....................................................5 6.5 Electrical Characteristics.............................................6 6.6 Operating Characteristics: TA = 25°C....................... 13 6.7 Typical Characteristics.............................................. 14 7 Parameter Measurement Information.......................... 16 7.1 Load Circuit and Voltage Waveforms........................16 8 Detailed Description......................................................18 8.1 Overview................................................................... 18 8.2 Functional Block Diagram......................................... 18 8.3 Feature Description...................................................18 8.4 Device Functional Modes..........................................20 9 Application and Implementation.................................. 21 9.1 Application Information............................................. 21 9.2 Typical Applications.................................................. 21 10 Power Supply Recommendations..............................24 11 Layout........................................................................... 24 11.1 Layout Guidelines................................................... 24 11.2 Layout Example...................................................... 24 12 Device and Documentation Support..........................25 12.1 Documentation Support.......................................... 25 12.2 接收文档更新通知................................................... 25 12.3 支持资源..................................................................25 12.4 Trademarks............................................................. 25 12.5 静电放电警告.......................................................... 25 12.6 术语表..................................................................... 25 13 Mechanical, Packaging, and Orderable Information.................................................................... 26 4 Revision History 注：以前版本的页码可能与当前版本的页码不同 Changes from Revision B (June 2020) to Revision C (September 2020) Page • Updated ICCA, ICCB, and ICCA + ICCB to reflect updated performance of device.................................................. 6 Changes from Revision A (January 2019) to Revision B (June 2020) Page • 向器件信息 表添加了 DRY 封装选项...................................................................................................................1 • Added pinout drawing for DRY package.............................................................................................................3 Changes from Revision * (December 2018) to Revision A (January 2019) • • • • 2 Page 向器件信息 表添加了 DBV 和 DTQ 封装选项..................................................................................................... 1 更新了修订历史记录 部分................................................................................................................................... 1 Added pinout drawings for DBV and DTQ packages .........................................................................................3 Added DRY package to Pin Configurations........................................................................................................3 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 5 Pin Configuration and Functions VCCA 1 6 VCCB GND 2 5 DIR A 3 B 4 VCCA 1 6 VCCB GND 2 5 DIR A 3 4 B 图 5-2. DCK Package 6-Pin SC70 Top View 图 5-1. DBV Package 6-Pin SOT-23 Top View VCCA 2 GND A 6 1 5 3 4 VCCB VCCA 1 6 VCCB DIR GND 2 5 DIR A 3 4 B B 图 5-3. DTQ Package 6-Pin X2SON Transparent Top View 图 5-4. DRY Package 6-Pin SON Transparent Top View Pin Functions PIN NO. NAME TYPE DESCRIPTION 1 VCCA — A-port supply voltage. 0.65 V ≤ VCCA ≤ 3.6 V. 2 GND — Ground 3 A I/O Input/output A. This pin is referenced to VCCA. 4 B I/O Input/output B. This pin is referenced to VCCB. 5 DIR I 6 VCCB — Direction control signal. See for functionality. B-port supply voltage. 0.65 V ≤ VCCB ≤ 3.6 V. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 3 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)(1) MIN MAX UNIT VCCA Supply voltage A –0.5 4.2 V VCCB Supply voltage B –0.5 4.2 V I/O Ports (A Port) –0.5 4.2 VI Input Voltage(2) I/O Ports (B Port) –0.5 4.2 Control Inputs –0.5 4.2 A Port –0.5 4.2 B Port –0.5 4.2 A Port –0.5 VCCA + 0.2 B Port –0.5 VCCB + 0.2 V VO Voltage applied to any output in the high-impedance or power-off state(2) VO Voltage applied to any output in the high or low state(2) (3) IIK Input clamp current VI < 0 –50 mA IOK Output clamp current VO < 0 –50 mA IO Continuous output current Continuous current through VCC or GND Tj Junction Temperature Tstg Storage temperature (1) (2) (3) V V –50 50 mA –100 100 mA 150 °C 150 °C –65 Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. The input voltage and output negative-voltage ratings may be exceeded if the input and output current ratings are observed. The output positive-voltage rating may be exceeded up to 4.2 V maximum if the output current rating is observed. 6.2 ESD Ratings VALUE V(ESD) (1) (2) 4 Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±8000 Charged device model (CDM), per JEDEC specification JESD22-C101(2) ±1000 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 6.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted)(1) (2) (3) MIN MAX UNIT VCCA Supply voltage A 0.65 3.6 V VCCB Supply voltage B 0.65 3.6 V Data Inputs VCCI = 0.65 V - 0.75 V VCCI x 0.70 VCCI = 0.76 V - 1 V VCCI x 0.70 VCCI = 1.1 V - 1.95 V VCCI x 0.65 VCCI = 2.3 V - 2.7 V VIH 1.6 VCCI = 3 V - 3.6 V High-level input voltage Control Input (DIR) Referenced to VCCA 2 VCCA = 0.65 V - 0.75 V VCCA x 0.70 VCCA = 0.76 V - 1 V VCCA x 0.70 VCCA = 1.1 V - 1.95 V VCCA x 0.65 VCCA = 2.3 V - 2.7 V 1.6 VCCA = 3 V - 3.6 V Data Inputs VIL Low-level input voltage Control Input (DIR) Referenced to VCCA V 2 VCCI = 0.65 V - 0.75 V VCCI x 0.30 VCCI = 0.76 V - 1 V VCCI x 0.30 VCCI = 1.1 V - 1.95 V VCCI x 0.35 VCCI = 2.3 V - 2.7 V 0.7 VCCI = 3 V - 3.6 V 0.8 VCCA = 0.65 V - 0.75 V VCCA x 0.30 VCCA = 0.76 V - 1 V VCCA x 0.30 VCCA = 1.1 V - 1.95 V VCCA x 0.35 VCCA = 2.3 V - 2.7 V 0.7 VCCA = 3 V - 3.6 V VI Input voltage (3) VO Output voltage Δt/Δv Input transition rate TA Operating free-air temperature (1) (2) (3) V 0.8 0 3.6 Active State 0 VCCO Tri-State 0 3.6 –40 V V 100 ns/V 125 °C VCCI is the VCC associated with the input port. VCCO is the VCC associated with the output port. All unused inputs of the device must be held at VCC or GND to ensure proper device operation. Refer to the TI application report, Implications of Slow or Floating CMOS Inputs. 6.4 Thermal Information SN74AXCH1T45 THERMAL METRIC(1) DBV (SOT-23) DCK (SC70) DTQ (X2SON) DRY (SON) UNIT 6 PINS 6 PINS 6 PINS 6 PINS Junction-to-ambient thermal resistance 214.0 223.9 327.8 308.3 °C/W Junction-to-case (top) thermal resistance 151.8 150.9 194.9 206.4 °C/W RθJB Junction-to-board thermal resistance 93.6 75.3 248.4 181.7 °C/W ψJT Junction-to-top characterization parameter 78.1 58.2 24.1 42.6 °C/W ψJB Junction-to-board characterization parameter 93.4 75.0 247.6 180.8 °C/W RθJA Rθ JC(top) (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 5 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 6.5 Electrical Characteristics over operating free-air temperature range (unless otherwise noted) (1) (2) Operating free-air temperature (TA) PARAMETER TEST CONDITIONS VCCA VCCB –40°C to 85°C MIN TYP(3) VOH VOL IBHL IBHH 6 High-level V = VIH output voltage I Low-level V = VIL output voltage I Bus-hold low sustaining current (4) –40°C to 125°C MAX MIN TYP MAX VCCO – 0.1 VCCO – 0.1 0.65 V 0.55 0.55 0.76 V 0.76 V 0.58 0.58 0.85 V 0.85 V 0.65 0.65 IOH = –3 mA 1.1 V 1.1 V 0.85 0.85 IOH = –6 mA 1.4 V 1.4 V 1.05 1.05 IOH = –8 mA 1.65 V 1.65 V 1.2 1.2 IOH = –9 mA 2.3 V 2.3 V 1.75 1.75 IOH = –12 mA 3V 3V IOL = 100 µA 0.7 V - 3.6 V 0.7 V - 3.6 V IOL = 50 µA 0.65 V 0.65 V 0.1 0.1 IOL = 200 µA 0.76 V 0.76 V 0.18 0.18 IOL = 500 µA 0.85 V 0.85 V 0.2 0.2 IOL = 3 mA 1.1 V 1.1 V 0.25 0.25 IOL = 6 mA 1.4 V 1.4 V 0.35 0.35 IOL = 8 mA 1.65 V 1.65 V 0.45 0.45 IOL = 9 mA 2.3 V 2.3 V 0.55 0.55 IOL = 12 mA 3V 3V 0.7 0.7 IOH = –100 µA 0.7 V - 3.6 V 0.7 V - 3.6 V IOH = –50 µA 0.65 V IOH = –200 µA IOH = –500 µA 2.3 V 2.3 0.1 0.1 VI = 0.20 V 0.65 V 0.65 V 4 4 VI = 0.23 V 0.76 V 0.76 V 8 7 VI = 0.26 V 0.85 V 0.85 V 10 10 VI = 0.39 V 1.1 V 1.1 V 20 20 VI = 0.49 V 1.4 V 1.4 V 40 30 VI = 0.58 V 1.65 V 1.65 V 55 45 VI = 0.7 V 2.3 V 2.3 V 90 80 VI = 0.8 V 3V 3V 145 135 VI = 0.45 V 0.65 V 0.65 V –4 –4 VI = 0.53 V 0.76 V 0.76 V –8 –7 VI = 0.59 V 0.85 V 0.85 V –10 –10 Bus-hold high VI = 0.71 V sustaining VI = 0.91 V current (5) 1.1 V 1.1 V –20 –20 1.4 V 1.4 V –40 –30 VI = 1.07 V 1.65 V 1.65 V –55 –45 VI = 1.6 V 2.3 V 2.3 V –90 –80 VI = 2.0 V 3V 3V –145 –135 Submit Document Feedback UNI T V µA µA Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 6.5 Electrical Characteristics (continued) over operating free-air temperature range (unless otherwise noted) (1) (2) Operating free-air temperature (TA) PARAMETER TEST CONDITIONS VCCA VCCB –40°C to 85°C MIN TYP(3) Bus-hold low overdrive current (6) IBHLO IBHHO II VI = 0 to VCC Bus-hold high overdrive VI = 0 to VCC current (7) Input leakage current 40 40 0.84 V 0.84 V 50 50 0.95 V 0.95 V 65 65 1.3 V 1.3 V 105 105 1.6 V 1.6 V 150 150 1.95 V 1.95 V 205 205 2.7 V 2.7 V 335 335 3.6 V 3.6 V 480 480 0.75 V 0.75 V –40 –40 0.84 V 0.84 V –50 –50 0.95 V 0.95 V –65 –65 1.3 V 1.3 V –105 –105 1.6 V 1.6 V –150 –150 1.95 V 1.95 V –205 –205 2.7 V 2.7 V –335 –335 3.6 V 3.6 V –480 –480 µA µA –1 1 A or B Port: Vi = VCCI or GND 0.65 V - 3.6 V 0.65 V - 3.6 V –4 4 –8 8 0V 0 V - 3.6 V –8 8 –12 12 0 V - 3.6 V 0V –8 8 –12 12 µA ICCA VI = VCCI or GND 0.65 V - 3.6 V 0.65 V - 3.6 V VI = VCCI or GND ICCA + Combined VI = VCCI ICCB supply current or GND IO = 0 IO = 0 IO = 0 Ci Control input capacitance VI = 3.3 V or GND Cio Data I/O capacitance, A Port Cio Data I/O capacitance, B Port (6) MAX 0.5 VCCA supply current (5) TYP –0.5 A or B Port: Vi or Vo = 0 V 3.6 V (1) (2) (3) (4) MIN 0.75 V 0.65 V - 3.6 V 0.65 V - 3.6 V Partial power down current VCCB supply current MAX 0.75 V Control input (DIR): VI = VCCA or GND Ioff ICCB UNI T –40°C to 125°C 0V 3.6 V 3.6 V 0V 8 –2 µA 12 µA –8 2 8 0.65 V - 3.6 V 0.65 V - 3.6 V 8 12 0V 3.6 V 2 8 µA 3.6 V 0V 16 µA –2 –8 0.65 V - 3.6 V 0.65 V - 3.6 V 3.3 V 10 3.3 V 4.3 4.3 pF VO = 1.65 V DC +1 MHz -16 3.3 V dBm sine wave 0V 7.4 7.4 pF VO = 1.65 V DC +1 MHz -16 0V dBm sine wave 3.3 V 7.4 7.4 pF VCCI is the VCC associated with the input port. VCCO is the VCC associated with the output port. All typical data is taken at 25°C. The bus-hold circuit can sink at least the minimum low sustaining current at VIL(MAX). IBHL should be measured after lowering VI to GND and then raising it to VIL(MAX). The bus-hold circuit can source at least the minimum high sustaining current at VIH(MIN). IBHH should be measured after raising VI to VCC and then lowering it to VIH(MIN). An external driver must source at least IBHLO to switch this node from low to high. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 7 SN74AXCH1T45 ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 (7) 8 www.ti.com.cn An external driver must sink at least IBHHO to switch this node from high to low. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 表 6-1. Switching Characteristics, VCCA = 0.7 V A tpd Propagation delay B DIR tdis A A Disable time DIR DIR ten B B A Enable time DIR B –40°C to 85°C 0.5 181 0.5 119 0.5 85 0.5 51 0.5 49 0.5 52 0.5 65 0.5 152 –40°C to 125°C 0.5 181 0.5 119 0.5 85 0.5 51 0.5 49 0.5 52 0.5 65 0.5 152 –40°C to 85°C 0.5 181 0.5 162 0.5 136 0.5 96 0.5 91 0.5 89 0.5 88 0.5 88 –40°C to 125°C 0.5 181 0.5 162 0.5 136 0.5 96 0.5 91 0.5 89 0.5 88 0.5 88 –40°C to 85°C 0.5 152 0.5 152 0.5 152 0.5 152 0.5 152 0.5 152 0.5 152 0.5 152 –40°C to 125°C 0.5 152 0.5 152 0.5 152 0.5 152 0.5 152 0.5 152 0.5 152 0.5 152 –40°C to 85°C 0.5 170 0.5 127 0.5 102 0.5 48 0.5 42 0.5 46 0.5 58 0.5 108 –40°C to 125°C 0.5 170 0.5 127 0.5 102 0.5 48 0.5 42 0.5 46 0.5 58 0.5 108 –40°C to 85°C 0.5 343 0.5 278 0.5 231 0.5 141 0.5 132 0.5 134 0.5 144 0.5 193 –40°C to 125°C 0.5 343 0.5 278 0.5 231 0.5 141 0.5 132 0.5 134 0.5 144 0.5 193 –40°C to 85°C 0.5 326 0.5 257 0.5 222 0.5 194 0.5 191 0.5 191 0.5 197 0.5 277 –40°C to 125°C 0.5 326 0.5 257 0.5 222 0.5 194 0.5 191 0.5 191 0.5 197 0.5 277 ns ns ns 表 6-2. Switching Characteristics, VCCA = 0.8 V A tpd Propagation delay B DIR tdis A A Disable time DIR DIR ten B B A Enable time DIR B –40°C to 85°C 0.5 162 0.5 98 0.5 65 0.5 33 0.5 28 0.5 26 0.5 27 0.5 37 –40°C to 125°C 0.5 162 0.5 98 0.5 65 0.5 33 0.5 28 0.5 26 0.5 27 0.5 37 –40°C to 85°C 0.5 119 0.5 98 0.5 81 0.5 54 0.5 45 0.5 44 0.5 43 0.5 42 –40°C to 125°C 0.5 119 0.5 98 0.5 81 0.5 54 0.5 45 0.5 44 0.5 43 0.5 42 –40°C to 85°C 0.5 107 0.5 107 0.5 107 0.5 107 0.5 107 0.5 107 0.5 107 0.5 107 –40°C to 125°C 0.5 107 0.5 107 0.5 107 0.5 107 0.5 107 0.5 107 0.5 107 0.5 107 –40°C to 85°C 0.5 160 0.5 117 0.5 90 0.5 39 0.5 31 0.5 29 0.5 29 0.5 37 –40°C to 125°C 0.5 160 0.5 117 0.5 90 0.5 39 0.5 31 0.5 29 0.5 29 0.5 37 –40°C to 85°C 0.5 268 0.5 205 0.5 165 0.5 90 0.5 74 0.5 71 0.5 70 0.5 77 –40°C to 125°C 0.5 268 0.5 205 0.5 165 0.5 90 0.5 74 0.5 71 0.5 70 0.5 77 –40°C to 85°C 0.5 257 0.5 194 0.5 161 0.5 130 0.5 125 0.5 126 0.5 125 0.5 132 –40°C to 125°C 0.5 257 0.5 194 0.5 161 0.5 130 0.5 125 0.5 126 0.5 125 0.5 132 ns ns ns Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 9 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 表 6-3. Switching Characteristics, VCCA = 0.9 V A tpd Propagation delay B DIR tdis A A Disable time DIR DIR ten B B A Enable time DIR B –40°C to 85°C 0.5 135 0.5 81 0.5 54 0.5 24 0.5 18 0.5 17 0.5 15 0.5 18 –40°C to 125°C 0.5 135 0.5 81 0.5 54 0.5 24 0.5 18 0.5 17 0.5 15 0.5 18 –40°C to 85°C 0.5 86 0.5 65 0.5 54 0.5 41 0.5 30 0.5 26 0.5 23 0.5 23 –40°C to 125°C 0.5 86 0.5 65 0.5 54 0.5 41 0.5 30 0.5 26 0.5 23 0.5 23 –40°C to 85°C 0.5 79 0.5 79 0.5 79 0.5 79 0.5 79 0.5 79 0.5 79 0.5 79 –40°C to 125°C 0.5 79 0.5 79 0.5 79 0.5 79 0.5 79 0.5 79 0.5 79 0.5 79 –40°C to 85°C 0.5 154 0.5 111 0.5 85 0.5 34 0.5 27 0.5 25 0.5 21 0.5 23 –40°C to 125°C 0.5 154 0.5 111 0.5 85 0.5 34 0.5 27 0.5 25 0.5 21 0.5 23 –40°C to 85°C 0.5 227 0.5 166 0.5 131 0.5 71 0.5 53 0.5 48 0.5 42 0.5 44 –40°C to 125°C 0.5 227 0.5 166 0.5 131 0.5 71 0.5 53 0.5 48 0.5 42 0.5 44 –40°C to 85°C 0.5 206 0.5 152 0.5 125 0.5 96 0.5 91 0.5 89 0.5 89 0.5 92 –40°C to 125°C 0.5 206 0.5 152 0.5 125 0.5 96 0.5 91 0.5 89 0.5 89 0.5 92 ns ns ns 表 6-4. Switching Characteristics, VCCA = 1.2 V A tpd Propagation delay B DIR tdis DIR A B A Enable time DIR 10 A Disable time DIR ten B B –40°C to 85°C 0.5 95 0.5 54 0.5 41 0.5 16 0.5 11 0.5 9 0.5 8 0.5 8 –40°C to 125°C 0.5 95 0.5 54 0.5 41 0.5 16 0.5 11 0.5 9 0.5 8 0.5 8 –40°C to 85°C 0.5 51 0.5 33 0.5 24 0.5 16 0.5 13 0.5 11 0.5 8 0.5 8 –40°C to 125°C 0.5 51 0.5 33 0.5 24 0.5 16 0.5 13 0.5 11 0.5 8 0.5 8 –40°C to 85°C 0.5 28 0.5 28 0.5 28 0.5 28 0.5 28 0.5 28 0.5 28 0.5 28 –40°C to 125°C 0.5 28 0.5 28 0.5 28 0.5 28 0.5 28 0.5 28 0.5 28 0.5 28 –40°C to 85°C 0.5 148 0.5 105 0.5 78 0.5 30 0.5 23 0.5 20 0.5 16 0.5 16 –40°C to 125°C 0.5 148 0.5 105 0.5 78 0.5 30 0.5 23 0.5 20 0.5 16 0.5 16 –40°C to 85°C 0.5 191 0.5 129 0.5 96 0.5 43 0.5 34 0.5 30 0.5 23 0.5 22 –40°C to 125°C 0.5 191 0.5 129 0.5 96 0.5 43 0.5 34 0.5 30 0.5 23 0.5 22 –40°C to 85°C 0.5 116 0.5 75 0.5 61 0.5 41 0.5 37 0.5 36 0.5 35 0.5 35 –40°C to 125°C 0.5 116 0.5 75 0.5 61 0.5 41 0.5 37 0.5 36 0.5 35 0.5 35 ns ns ns Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 表 6-5. Switching Characteristics, VCCA = 1.5 V A tpd Propagation delay B DIR tdis A A Disable time DIR DIR ten B B A Enable time DIR B –40°C to 85°C 0.5 91 0.5 45 0.5 30 0.5 13 0.5 9 0.5 8 0.5 6 0.5 6 –40°C to 125°C 0.5 91 0.5 45 0.5 30 0.5 13 0.5 9 0.5 8 0.5 6 0.5 6 –40°C to 85°C 0.5 49 0.5 28 0.5 18 0.5 11 0.5 9 0.5 8 0.5 6 0.5 5 –40°C to 125°C 0.5 49 0.5 28 0.5 18 0.5 11 0.5 9 0.5 8 0.5 6 0.5 5 –40°C to 85°C 0.5 20 0.5 20 0.5 20 0.5 20 0.5 20 0.5 20 0.5 20 0.5 20 –40°C to 125°C 0.5 20 0.5 20 0.5 20 0.5 20 0.5 20 0.5 20 0.5 20 0.5 20 –40°C to 85°C 0.5 146 0.5 103 0.5 76 0.5 28 0.5 21 0.5 19 0.5 15 0.5 14 –40°C to 125°C 0.5 146 0.5 103 0.5 76 0.5 28 0.5 21 0.5 19 0.5 15 0.5 14 –40°C to 85°C 0.5 186 0.5 124 0.5 89 0.5 38 0.5 29 0.5 26 0.5 20 0.5 18 –40°C to 125°C 0.5 186 0.5 124 0.5 89 0.5 38 0.5 29 0.5 26 0.5 20 0.5 18 –40°C to 85°C 0.5 104 0.5 58 0.5 43 0.5 31 0.5 28 0.5 27 0.5 25 0.5 25 –40°C to 125°C 0.5 104 0.5 58 0.5 43 0.5 31 0.5 28 0.5 27 0.5 25 0.5 25 ns ns ns 表 6-6. Switching Characteristics, VCCA = 1.8 V A tpd Propagation delay B DIR tdis A A Disable time DIR DIR ten B B A Enable time DIR B –40°C to 85°C 0.5 89 0.5 44 0.5 26 0.5 11 0.5 8 0.5 7 0.5 6 0.5 5 –40°C to 125°C 0.5 89 0.5 44 0.5 26 0.5 11 0.5 8 0.5 7 0.5 6 0.5 5 –40°C to 85°C 0.5 52 0.5 26 0.5 17 0.5 9 0.5 8 0.5 7 0.5 6 0.5 5 –40°C to 125°C 0.5 52 0.5 26 0.5 17 0.5 9 0.5 8 0.5 7 0.5 6 0.5 5 –40°C to 85°C 0.5 17 0.5 17 0.5 17 0.5 17 0.5 17 0.5 17 0.5 17 0.5 17 –40°C to 125°C 0.5 17 0.5 17 0.5 17 0.5 17 0.5 17 0.5 17 0.5 17 0.5 17 –40°C to 85°C 0.5 147 0.5 103 0.5 76 0.5 27 0.5 20 0.5 18 0.5 14 0.5 13 –40°C to 125°C 0.5 147 0.5 103 0.5 76 0.5 27 0.5 20 0.5 18 0.5 14 0.5 13 –40°C to 85°C 0.5 185 0.5 122 0.5 86 0.5 35 0.5 27 0.5 24 0.5 19 0.5 17 –40°C to 125°C 0.5 185 0.5 122 0.5 86 0.5 35 0.5 27 0.5 24 0.5 19 0.5 17 –40°C to 85°C 0.5 100 0.5 54 0.5 37 0.5 27 0.5 25 0.5 24 0.5 22 0.5 22 –40°C to 125°C 0.5 100 0.5 54 0.5 37 0.5 27 0.5 25 0.5 24 0.5 22 0.5 22 ns ns ns Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 11 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 表 6-7. Switching Characteristics, VCCA = 2.5 V A tpd Propagation delay B DIR tdis A A Disable time DIR DIR ten B B A Enable time DIR B –40°C to 85°C 0.5 88 0.5 42 0.5 23 0.5 8 0.5 6 0.5 6 0.5 5 0.5 5 –40°C to 125°C 0.5 88 0.5 42 0.5 23 0.5 8 0.5 6 0.5 6 0.5 5 0.5 5 –40°C to 85°C 0.5 65 0.5 27 0.5 15 0.5 8 0.5 6 0.5 6 0.5 5 0.5 4 –40°C to 125°C 0.5 65 0.5 27 0.5 15 0.5 8 0.5 6 0.5 6 0.5 5 0.5 4 –40°C to 85°C 0.5 13 0.5 13 0.5 13 0.5 13 0.5 13 0.5 13 0.5 13 0.5 13 –40°C to 125°C 0.5 13 0.5 13 0.5 13 0.5 13 0.5 13 0.5 13 0.5 13 0.5 13 –40°C to 85°C 0.5 146 0.5 102 0.5 75 0.5 27 0.5 19 0.5 17 0.5 13 0.5 12 –40°C to 125°C 0.5 146 0.5 102 0.5 75 0.5 27 0.5 19 0.5 17 0.5 13 0.5 12 –40°C to 85°C 0.5 191 0.5 122 0.5 85 0.5 33 0.5 25 0.5 22 0.5 17 0.5 16 –40°C to 125°C 0.5 191 0.5 122 0.5 85 0.5 33 0.5 25 0.5 22 0.5 17 0.5 16 –40°C to 85°C 0.5 95 0.5 50 0.5 31 0.5 20 0.5 18 0.5 17 0.5 17 0.5 17 –40°C to 125°C 0.5 95 0.5 50 0.5 31 0.5 20 0.5 18 0.5 17 0.5 17 0.5 17 ns ns ns 表 6-8. Switching Characteristics, VCCA = 3.3 V A tpd Propagation delay B DIR tdis DIR A B A Enable time DIR 12 A Disable time DIR ten B B –40°C to 85°C 0.5 87 0.5 42 0.5 23 0.5 8 0.5 5 0.5 5 0.5 4 0.5 4 –40°C to 125°C 0.5 87 0.5 42 0.5 23 0.5 8 0.5 5 0.5 5 0.5 4 0.5 4 –40°C to 85°C 0.5 154 0.5 37 0.5 18 0.5 8 0.5 6 0.5 5 0.5 5 0.5 4 –40°C to 125°C 0.5 154 0.5 37 0.5 18 0.5 8 0.5 6 0.5 5 0.5 5 0.5 4 –40°C to 85°C 0.5 12 0.5 12 0.5 12 0.5 12 0.5 12 0.5 12 0.5 12 0.5 12 –40°C to 125°C 0.5 12 0.5 12 0.5 12 0.5 12 0.5 12 0.5 12 0.5 12 0.5 12 –40°C to 85°C 0.5 147 0.5 102 0.5 75 0.5 26 0.5 19 0.5 17 0.5 13 0.5 12 –40°C to 125°C 0.5 147 0.5 102 0.5 75 0.5 26 0.5 19 0.5 17 0.5 13 0.5 12 –40°C to 85°C 0.5 275 0.5 129 0.5 88 0.5 34 0.5 24 0.5 21 0.5 17 0.5 16 –40°C to 125°C 0.5 275 0.5 129 0.5 88 0.5 34 0.5 24 0.5 21 0.5 17 0.5 16 –40°C to 85°C 0.5 94 0.5 49 0.5 30 0.5 18 0.5 16 0.5 16 0.5 15 0.5 15 –40°C to 125°C 0.5 94 0.5 49 0.5 30 0.5 18 0.5 16 0.5 16 0.5 15 0.5 15 ns ns ns Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 6.6 Operating Characteristics: TA = 25°C PARAMETER Power Dissipation Capacitance per transceiver (A to B: outputs enabled) CpdA Power Dissipation Capacitance per transceiver (B to A: outputs enabled) Power Dissipation Capacitance per transceiver (A to B: outputs enabled) CpdB Power Dissipation Capacitance per transceiver (B to A: outputs enabled) TEST CONDITIONS VCCA VCCB MIN TYP 0.7 V 0.7 V 2.0 0.8 V 0.8 V 2.0 0.9 V 0.9 V 2.0 CL = 0, RL = Open f = 1 1.2 V MHz, tr = tf = 1 ns 1.5 V 1.2 V 2.0 1.5 V 1.9 1.8 V 1.8 V 2.0 2.5 V 2.5 V 2.4 3.3 V 3.3 V 3.0 0.7 V 0.7 V 12 0.8 V 0.8 V 12 0.9 V 0.9 V 12 CL = 0, RL = Open f = 1 1.2 V MHz, tr = tf = 1 ns 1.5 V 1.2 V 12 1.5 V 13 1.8 V 1.8 V 13 2.5 V 2.5 V 17 3.3 V 3.3 V 21 0.7 V 0.7 V 12 0.8 V 0.8 V 12 0.9 V 0.9 V 12 CL = 0, RL = Open f = 1 1.2 V MHz, tr = tf = 1 ns 1.5 V 1.2 V 12 1.5 V 13 1.8 V 1.8 V 13 2.5 V 2.5 V 17 3.3 V 3.3 V 21 0.7 V 0.7 V 2.1 0.8 V 0.8 V 2.2 0.9 V 0.9 V 2.2 CL = 0, RL = Open f = 1 1.2 V MHz, tr = tf = 1 ns 1.5 V 1.2 V 2.2 1.5 V 2.3 1.8 V 1.8 V 2.3 2.5 V 2.5 V 2.6 3.3 V 3.3 V 3.3 MAX UNIT pF pF pF pF Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 13 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 6.7 Typical Characteristics 50 45 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 40 35 30 25 20 15 0.6 TA = 25°C 0.9 1.2 1.5 1.8 2.1 Supply B (V) 2.4 2.7 3 VCCA = 0.7 V Propagation delay (ns) Propagation delay (ns) 20 15 1.8 2.1 Supply B (V) 2.4 2.7 3 3.3 D001 VCCA = 0.8 V CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 24 21 18 15 12 9 0.9 1.2 1.5 1.8 2.1 Supply B (V) 2.4 2.7 3 6 0.6 3.3 0.9 1.2 1.5 D002 VCCA = 0.9 V TA = 25°C 1.8 2.1 Supply B (V) 2.4 2.7 3 3.3 D003 VCCA = 1.2 V 图 6-4. Typical Propagation Delay of Low-to-High (A to B) vs Load Capacitance 30 27 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 24 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 24 Propagation delay (ns) 27 Propagation delay (ns) 1.5 27 图 6-3. Typical Propagation Delay of Low-to-High (A to B) vs Load Capacitance 21 18 15 12 9 21 18 15 12 9 6 0.9 1.2 1.5 1.8 2.1 Supply B (V) 2.4 2.7 3 3 0.6 3.3 0.9 1.2 1.5 D004 TA = 25°C VCCA = 1.5 V 1.8 2.1 Supply B (V) 2.4 2.7 3 3.3 D005 TA = 25°C VCCA = 1.8 V 图 6-5. Typical Propagation Delay of Low-to-High (A to B) vs Load Capacitance 图 6-6. Typical Propagation Delay of Low-to-High (A to B) vs Load Capacitance 27 27 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 21 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 24 Propagation delay (ns) 24 Propagation delay (ns) 1.2 图 6-2. Typical Propagation Delay of Low-to-High (A to B) vs Load Capacitance 10 18 15 12 9 6 21 18 15 12 9 6 0.9 1.2 1.5 1.8 2.1 Supply B (V) 2.4 2.7 3 3.3 3 0.6 D007 VCCA = 3.3 V TA = 25°C 图 6-7. Typical Propagation Delay of Low-to-High (A to B) vs Load Capacitance 14 0.9 30 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 25 TA = 25°C 20 TA = 25°C 30 3 0.6 25 D016 35 6 0.6 30 10 0.6 3.3 40 TA = 25°C 35 15 图 6-1. Typical Propagation Delay of Low-to-High (A to B) vs Load Capacitance 5 0.6 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 40 Propagation delay (ns) Propagation delay (ns) 45 0.9 1.2 1.5 1.8 2.1 Supply B (V) 2.4 2.7 3 3.3 D006 VCCA = 2.5 V 图 6-8. Typical Propagation Delay of Low-to-High (A to B) vs Load Capacitance Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 50 40 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 40 35 30 25 TA = 25°C 0.9 1.2 1.5 1.8 2.1 Supply A (V) 2.4 2.7 3 VCCA = 0.7 V TA = 25°C 27 24 21 18 15 1.8 2.1 Supply A (V) 2.4 2.7 3 3.3 D009 VCCA = 0.8 V CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 22.5 20 17.5 15 12.5 10 0.9 1.2 1.5 1.8 2.1 Supply A (V) 2.4 2.7 3 7.5 0.6 3.3 0.9 1.2 1.5 D010 VCCA = 0.9 V TA = 25°C 图 6-11. Typical Propagation Delay of Low-to-High (B to A) vs Load Capacitance 1.8 2.1 Supply A (V) 2.4 2.7 3 3.3 D011 VCCA = 1.2 V 图 6-12. Typical Propagation Delay of Low-to-High (B to A) vs Load Capacitance 30 25 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 24 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 22.5 Propagation delay (ns) 27 Propagation delay (ns) 1.5 25 12 21 18 15 12 9 20 17.5 15 12.5 10 7.5 0.9 1.2 1.5 1.8 2.1 Supply A (V) 2.4 2.7 3 5 0.6 3.3 0.9 1.2 1.5 D012 VCCA = 1.5 V TA = 25°C 图 6-13. Typical Propagation Delay of Low-to-High (B to A) vs Load Capacitance 1.8 2.1 Supply A (V) 2.4 2.7 3 3.3 D013 VCCA = 1.8 V 图 6-14. Typical Propagation Delay of Low-to-High (B to A) vs Load Capacitance 30 30 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 27 Propagation delay (ns) 25 Propagation delay (ns) 1.2 图 6-10. Typical Propagation Delay of Low-to-High (B to A) vs Load Capacitance Propagation delay (ns) Propagation delay (ns) 30 TA = 25°C 0.9 27.5 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 33 6 0.6 20 D008 36 TA = 25°C 25 10 0.6 3.3 图 6-9. Typical Propagation Delay of Low-to-High (B to A) vs Load Capacitance 9 0.6 30 15 20 15 0.6 CL = 45 pF CL = 62 pF CL = 79 pF CL = 105 pF CL = 123 pF 35 Propagation delay (ns) Propagation delay (ns) 45 20 15 10 24 21 18 15 12 9 6 5 0.6 0.9 1.2 1.5 1.8 2.1 Supply A (V) 2.4 2.7 3 3.3 3 0.6 D014 TA = 25°C VCCA = 2.5 V TA = 25°C 图 6-15. Typical Propagation Delay of Low-to-High (B to A) vs Load Capacitance 0.9 1.2 1.5 1.8 2.1 Supply A (V) 2.4 2.7 3 3.3 D015 VCCA = 3.3 V 图 6-16. Typical Propagation Delay of Low-to-High (B to A) vs Load Capacitance Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 15 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 7 Parameter Measurement Information 7.1 Load Circuit and Voltage Waveforms Unless otherwise noted, all input pulses are supplied by generators having the following characteristics: • f = 1 MHz • ZO = 50 Ω • dv/dt ≤ 1 ns/V Measurement Point 2 x VCCO S1 RL Open Output Pin Under Test GND CL(1) A. RL CL includes probe and jig capacitance. 图 7-1. Load Circuit 表 7-1. Load Circuit Conditions Parameter VCCO RL CL S1 VTP Δt/ Δv Input transition rise or fall rate 0.65 V – 3.6 V 1 MΩ 15 pF Open N/A 1.1 V – 3.6 V 2 kΩ 15 pF Open N/A tpd Propagation (delay) time 0.65 V – 0.95 V 20 kΩ 15 pF Open N/A 3 V – 3.6 V 2 kΩ 15 pF 2 × VCCO 0.3 V 1.65 V – 2.7 V 2 kΩ 15 pF 2 × VCCO 0.15 V ten, tdis Enable time, disable time ten, tdis Enable time, disable time 1.1 V – 1.6 V 2 kΩ 15 pF 2 × VCCO 0.1 V 0.65 V – 0.95 V 20 kΩ 15 pF 2 × VCCO 0.1 V 3 V – 3.6 V 2 kΩ 15 pF GND 0.3 V 1.65 V – 2.7 V 2 kΩ 15 pF GND 0.15 V 1.1 V – 1.6 V 2 kΩ 15 pF GND 0.1 V 0.65 V – 0.95 V 20 kΩ 15 pF GND 0.1 V VCCI(1) VCCI(1) Input A, B Input A, B VCCI / 2 VCCI / 2 500 ps/V ± 100 ns/V 0V VOH(2) VCCI / 2 Output B, A VCCI / 2 VOL(2) 1. 2. 0V VOH(2) tpd tpd Output B, A 100 kHz VCCI is the supply pin associated with the input port. VOH and VOL are typical output voltage levels that occur with specified RL, CL, and S1 1. 2. Ensure Monotonic Rising and Falling Edge VOL(2) VCCI is the supply pin associated with the input port. VOH and VOL are typical output voltage levels that occur with specified RL, CL, and S1 图 7-3. Input Transition Rise or Fall Rate 图 7-2. Propagation Delay 16 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 VCCA DIR VCCA / 2 VCCA / 2 GND ten(1) Output A (2) VCCO(5) VCCO / 2 VOL + VTP VOL(6) tdis VOH(6) Output A VOH - VTP (3) VCCO / 2 GND ten(1) Output B(2) VCCO(5) VCCO / 2 VOL + VTP VOL(6) tdis VOH(6) Output B (3) VCCO / 2 VOH - VTP GND 1. 2. 3. 4. 5. 6. Illustrative purposes only. Enable Time is a calculation as described in the data sheet. Output waveform on the condition that input is driven to a valid Logic Low. Output waveform on the condition that input is driven to a valid Logic High. VCCI is the supply pin associated with the input port VCCO is the supply pin associated with the output port. VOH and VOL are typical output voltage levels that occur with specified RL, CL, and S1 图 7-4. Disable and Enable Time Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: SN74AXCH1T45 17 SN74AXCH1T45 www.ti.com.cn ZHCSJ32C – DECEMBER 2018 – REVISED SEPTEMBER 2020 8 Detailed Description 8.1 Overview The SN74AXCH1T45 is single-bit, dual-supply, noninverting voltage level translator. Pin A and the direction control pin are referenced to VCCA logic levels and pin B is referenced to VCCB logic levels, as depicted in . The A port can accept I/O voltages ranging from 0.65 V to 3.6 V, and the B port can accept I/O voltages from 0.65 V to 3.6 V. A logic high on the DIR pin enables data transmission from A to B and a logic low on the DIR pin enables data transmission from B to A. 8.2 Functional Block Diagram VCCA VCCB DIR Bus-Hold B A Bus-Hold 图 8-1. Functional Block Diagram 8.3 Feature Description 8.3.1 Standard CMOS Inputs Standard CMOS inputs are high impedance and are typically modeled as a resistor in parallel with the input capacitance given in the Electrical Characteristics. The worst case resistance is calculated with the maximum input voltage, given in the Absolute Maximum Ratings, and the maximum input leakage current, given in the Electrical Characteristics, using ohm's law (R = V ÷ I). Signals applied to the inputs need to have fast edge rates, as defined by Δt/Δv in Recommended Operating Conditions to avoid excessive current consumption and oscillations. If a slow or noisy input signal is required, a device with a Schmitt-trigger input should be used to condition the input signal prior to the standard CMOS input. 8.3.2 Balanced High-Drive CMOS Push-Pull Outputs A balanced output allows the device to sink and source similar currents. The high drive capability of this device creates fast edges into light loads so routing and load conditions should be considered to prevent ringing. Additionally, the outputs of this device are capable of driving larger currents than the device can sustain without being damaged. The electrical and thermal limits defined in the Absolute Maximum Ratings must be followed at all times. 8.3.3 Partial Power Down (Ioff) The inputs and outputs for this device enter a high-impedance state when the device is powered down, inhibiting current backflow into the device. The maximum leakage into or out of any input or output pin on the device is specified by Ioff in the Electrical Characteristics. 8.3.4 VCC Isolation The inputs and outputs for this device enter a high-impedance state when either supply is