These synchronous presettable counters feature an inter- nal carry look-ahead for application in high-speed counting designs The LSA and LSA are. SN74LSADR. SOIC. D. Q1. SN74LSANSR. SO. NS. Q1. Texas Instruments 74LS Counter ICs are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas Instruments 74LS
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We think you have liked this presentation. If you wish to download it, daasheet recommend it to your friends in any social system. Share buttons are a little bit lower. Published by Lester Phillips Modified over 3 years ago. Provide examples of 3-Bit and 4-Bit synchronous up counters.
Provide examples of 3-Bit and 4-Bit synchronous down counters.
Synchronous counters are faster than asynchronous counters of the simultaneous clocking. Synchronous counters do not suffer from the ripple effect that asynchronous counters do. Synchronous counters require more logic an asynchronous counters. This slide provides the definition of synchronous counters.
Synchronous Counters with SSI Gates – ppt video online download
Project Lead The Way, Inc. Provide an examples of a counter application implemented with the 74LS Are the data inputs, this is the data that can be load into the counter. This is how the lower limit of the count is set.
Are the data outputs. This is the count of the counter. These are enable 74lz163. They both need to be a logic 1 for the counter to be enabled. For most free running counters, these input will be tied high. This is the load input. When this input is a logic 0the data on the Data Input lines is loaded into the counter. Note, LOAD is a synchronous input.
Thus, the Data Input will be loaded into the counter on the next rising edge of the clock when the LOAD input is a logic 0.
74LS Datasheet pdf – Synchronous 4-Bit Binary Counters – Fairchild Semiconductor
This is the clear input. When this input is a logic 0and the counter is disabled, the counter will be cleared.
The counter must first be disabled, then cleared. This is the clock input.
It is a positive edge trigger clock. This is the Ripple Carry Output. This output is a logic 1 when the counter is at it upper limit This signal is typically used to when the multiple counters are cascaded.
The students are not responsible for this material, but it is here just as a reference to show them the complexity of this MSI counter. Also, point out the all the clocks are tied together, that is why this is a synchronous counter design. LOAD set to a logic 0 ; Outputs are loaded with input data on next rising edge of clock.
In this example a 12 is loaded. Since we will only be discussing the 74LS the two waveform on the diagram the are for the 74LS can be ignored. On every rising edge of clock, the output count is incremented by one. In this example 12, 13, 14, 15, 0, 1, 2. Note, when the count is 15, RCO is a logic 1 for the full clock cycle. ENT set to a logic 0 ; Counting is disabled.
Because the LOAD signal is a synchronous input, input data of 3 is not loaded until the next rising edge of the clock. This is the clock input for the up counter.
DOWN must be held at a logic 1. This is the clock input for the down counter. UP must be held at a logic 1. Note, LOAD is an asynchronous input. Thus, the Data Input will be loaded immediately. When this input is a logic 1the counter will be cleared. Note, CLR is an asynchronous input. Thus, the Data Output will be cleared immediately.
This is the Carry Output. This output is a logic 0 when the counter is at it upper limit when the counter is an up counter. This is the Borrow Output. This output is a logic 0 when the counter is at it lower when the counter is a down counter.
CLEAR is an asynchronous input. LOAD set to a logic 0 ; Outputs are loaded with input data immediately. In this case13 LOAD is an asynchronous input.
Shown is the composite timing diagram for the 74LS counter. In this example 13, 14, 15, 0, 1, 2. On every rising edge of clock, the output count is decremented by one.
In this example 2, 1, 0, 15, 14, Note, LOAD signal goes low when the count is 2 Sequential logic design practices 1.
The number of states in the cycle. Katz Transparency No Chapter 7: Sequential Logic Case Studies 7. My presentations Profile Feedback Log out.