Synchronous Counters Lecture Overview n Classifications of Counters

Synchronous Counters

Lecture Overview n Classifications of Counters n Definitions n Synchronous Counter… n n n Modulus 8 with Discrete Gates (SSI) Modulus 16 with Discrete Gates (SSI) 74 LS 163 Synchronous 4 Bit Counter n n Understanding Device Truncated Count

Classifications of Counters n Asynchronous Counters n n Only the first flip-flop is clocked by an external clock. All subsequent flip-flops are clocked by the output of the preceding flip-flop. Asynchronous counters are slower than synchronous counters because of the delay in the transmission of the pulses from flip-flop to flip-flop. Asynchronous counters are also called ripple-counters because of the way the clock pulse ripples it way through the flip-flops. Synchronous Counters n n n All flip-flops are simultaneously clocked by an external clock. Synchronous counters are faster than asynchronous counters because of the simultaneous clocking. Synchronous counters are an example of a state machines design.

Modulus-8 Synch Counter Analyses Q 2 Q 1 Q 0 n Q 0 : Toggles Every Time… J 0 & K 0 = 1 n Q 1 : Toggles When Q 0=1… J 1 & K 1 = Q 0 n Q 2 : Toggles When Q 0=1 & Q 1=1… J 2 & K 2 = Q 1 x Q 0

Modulus-8 Synch Counter Design

Modulus-16 Synch Counter Analyses Q 3 Q 2 Q 1 Q 0 n Q 0 : Toggles Every Time… J 0 & K 0 = 1 n Q 1 : Toggles When Q 0=1… J 1 & K 1 = Q 0 n Q 2 : Toggles When Q 0=1 & Q 1=1… J 2 & K 2 = Q 1 x Q 0 n Q 3 : Toggles When Q 0=1 & Q 1=1 & Q 2=1… J 3 & K 3 = Q 2 x. Q 1 x. Q 0

Modulus-16 Synch Counter Design

74 LS 163 Synchronous 4 Bit Counter Clear Terminal Count Data In Data Out Enables Load Data

74 LS 163 : How It Works

74 LS 163 : 6 (0110) to 15 (1111) CNT

74 LS 163 : 6 (0110) to 12 (1100) CNT

Understanding Circuit Maker Labels DATA SHEET CIRCUIT MAKER