This webpage doesn't work with Internet Explorer. Please use the latest version of Google Chrome, Microsoft Edge, Mozilla Firefox or Safari.
请输入3个以上字符
The information presented in this cross reference is based on TOSHIBA's selection criteria and should be treated as a suggestion only. Please carefully review the latest versions of all relevant information on the TOSHIBA products, including without limitation data sheets and validate all operating parameters of the TOSHIBA products to ensure that the suggested TOSHIBA products are truly compatible with your design and application.
Please note that this cross reference is based on TOSHIBA's estimate of compatibility with other manufacturers' products, based on other manufacturers' published data, at the time the data was collected.
TOSHIBA is not responsible for any incorrect or incomplete information. Information is subject to change at any time without notice.
请输入3个以上字符
什么是输出容限功能?
CMOS逻辑IC的输出电路具有图腾柱配置,由如下所示的一对p沟道和n沟道MOSFET组成。通常,CMOS逻辑IC在输出端和电源之间有一个寄生二极管。
当在关断状态下向IC施加电压或在打开状态下向具有三态输出的IC(例如74LCX245)施加电压时,寄生二极管就会导通。产生的大电流可能会损坏IC。
即使将高于供电电压(VCC)的电压施加到输出端,电流也不会流入具有这种寄生二极管的输出配置的IC中。此IC具有输出容限功能。
很容易区分一个IC是否具有输出容限功能。
让我们看一下74VHC和74LCX系列IC的数据表。
请参阅工作范围表中显示的总线I/O电压。
74VHC245的数据表显示VIO=0至VCC。这意味着输出引脚的最大容限为VCC。因此,74VHC245没有输出容限功能。
相比之下,74LCX245的数据表显示VIN=0至5.5V,这意味着无论VCC如何,总线I/O引脚都可以施加高达5.5V的电压。因此,74LCX245具有输出容限功能。