器件名称:
DM74LS197N
功能描述:
Presettable Binary Counters
文件大小:
117.4KB 共6页
简 介:
DM74LS197 Presettable Binary Counters February 1992 DM74LS197 Presettable Binary Counters General Description The ’LS197 ripple counter contains divide-by-two and divide-by-eight sections which can be combined to form a modulo-16 binary counter State changes are initiated by the falling edge of the clock The ’LS197 has a Master Reset (MR) input which overrides all other inputs and asynchronously forces all outputs LOW A Parallel Load input (PL) overrides clocked operations and asynchronously loads the data on the Parallel Data inputs (Pn) into the flipflops This preset feature makes the circuit usable as a programmable counter The circuit can also be used as a 4-bit latch loading data from the Parallel Data inputs when PL is LOW and storing the data when PL is HIGH For detail specifications and functional description please refer to the ’LS196 data sheet Features Y Y Y High counting rates Typically 70 MHz Asynchronous preset Asynchronous master reset Connection Diagram Dual-In-Line Package TL F 10180 – 1 Order Number DM74LS197M or DM74LS197N See NS Package Number M14A or N14A Mode Select Table Pin Names CP0 CP1 MR P0 – P3 PL Q0 Q1 – Q3 Description d 2 Section Clock Input Inputs MR L H H PL X L H CP X X K Response Qn Forced LOW Pn x Qn Count Up (Active Falling Edge) d 8 Section Clock Input (Active Falling Edge) Asynchronous Master Reset Input (Active LOW) Parallel Data Inputs Asynchronous Parallel Load Input (Active LOW) d 2 Section Output d 8 Section Outputs H e HI……
