Presentation on theme: "EET 1131 Unit 11 Counter Circuits Read Kleitz, Chapter 12, skipping Sections 12-10 and 12-11. Homework #11 and Lab #11 due next week. Quiz next week."— Presentation transcript:
EET 1131 Unit 11 Counter Circuits Read Kleitz, Chapter 12, skipping Sections 12-10 and 12-11. Homework #11 and Lab #11 due next week. Quiz next week.
Synchronous versus Asynchronous The synchronous/asynchronous distinction has different meanings: 1. As applied to inputs: A change on a synchronous input doesn’t affect the outputs until the next active clock edge, but a change on an asynchronous input affects the outputs immediately. 2. As applied to counters: in a synchronous counter, the outputs can all change at the same instant; but in an asynchronous counter, there’s a brief delay between the changing of the outputs.
7447 BCD-to-7-Segment Decoder/Driver 4 input pins for BCD code. 7 output pins to control the seven segments of a 7-segement display. Also has a lamp test input. Also a ripple-blanking input and output to suppress leading or trailing zeroes. Data sheet: 74477447
Some Up/Down Synchronous Counter ICs 74190 Four bit up/down decade counter (MOD 10) 74190 74191 Four bit up/down binary counter (MOD 16)
Cascading Counters Most counter chips are 4-bit counters, with a modulus of 16 or less. To get larger moduli, you cascade two or more counter chips together. When you cascade counters, their moduli multiply, not add. Example: If you cascade a MOD-10 counter with a MOD-16 counter, you get a MOD-160 counter. The connections for cascading counters differ depending on whether you’re using asynchronous counters or synchronous counters.