ZHCSRM0G December 1982 – April 2021 SN54HC20 , SN74HC20
PRODUCTION DATA
請參考 PDF 數據表獲取器件具體的封裝圖。
In this application, two 4-input NAND gates are used to create an active-low SR latch as shown in GUID-1EBAA6F8-BE2B-4CF9-B16A-ABF0D104C8C8.html#APP1_SCHEM. Unused inputs can be tied together or to VCC
This device is used to drive the tamper indicator LED and provide one bit of data to the system controller. When the tamper switch outputs LOW, the output Q becomes HIGH. This output remains HIGH until the system controller addresses the event and sends a LOW signal to the R input which returns the Q output back to LOW.