SN74LS490

DUAL DECADE COUNTER The SN54 / 74LS490 contains a pair of high-speed 4-stage ripple counters. Each half of the SN54 / 74LS490 has individual Clock, Master Reset and Master Set (Preset 9) inputs. Each section counts in the 8, 4, 2, 1 BCD code. Dual Version of SN54 / 74LS490 Individual Asynchronous Clear and Preset to 9 for Each Counter Count Frequency — Typically 65 MHz Input Clamp Diodes Limit High-Speed Termination Effects CONNECTION DIAGRAM DIP (TOP VIEW) VCC CPb MRb Q0b MSb Q1b Q2b Q3b 16 15 14 13 12 11 10 9 1 2 3 4 56 78 CPa MRa Q0a MSa Q1a Q2a Q3a GND PIN NAMES LOADING (Note a) HIGH LOW MS MR CP Q0 – Q3 Master Set (Set to 9) Input Master Reset Clock Input (Active LOW Going Edge) Counter Outputs (Note b) 0.5 U.L. 0.5 U.L. 1.5 U.L. 10 U.L. 0.25 U.L. 0.25 U.L. 1.5 U.L. 5 (2.5) U.L. NOTES: a) 1 TTL Unit Load (U.L.) = 40 µA HIGH/1.6 mA LOW. b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74) Temperature Ranges. L...