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我设备是1.8V的GPRS模块,MCU是3.3V。 以前一直是用的SN74AVCH4T245。这次供应商疏忽发成了SN74AVC4T245 。我怕使用有问题,又找不到两者的大区别别。请专家解释一下两款芯片的最大区别。 用混了有啥不良后果。谢谢了!
SN74AVCH4T245中的H意思为bus-hold 。说明这款器件带有总线保持电路,简单来说,就是可以维持输出在一个有效的逻辑电平内,即使输入是一个无效的逻辑状态,通常情况下,不带总线保持功能的,不建议输入端直接悬空,我们需要上拉或下拉使得输入端在一个有效的逻辑电平内,而这种则不需要上下拉:
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.