Questions tagged [digital-logic]
Digital electronics treats discrete signals, unlike analog electronics which treats continuous signals. Digital logic is used to perform arithmetic operations with electric signals and constitutes the base for building CPUs.
5,002 questions
3 votes
1 answer
102 views
Control voltages for for driving a CD4067B multiplexer
What control (address, enable) voltages do i need if i want to drive a CD4067B that is powered with +/-12V? The datasheet is confusing. Is it 0V to VDD or is it VSS to around 0V? The part only accepts ...
- 307
-1 votes
2 answers
81 views
How to make a negative edge triggered design?
I saw this gate implementation of a circuit using a NOT gate as one of the inputs for an AND gate. This meant that when the input goes from high to low, the AND gate output goes high for a fraction of ...
1 vote
4 answers
147 views
How to modify a 4-bit D-Flip-Flop counter to count only 0–9? (Synchronic)?
I’m a computer science student currently building a 4-bit D-Flip-Flop counter. With the basic structure, the counter normally counts from 0 to 15 (a full 4-bit cycle). However, for my lab tomorrow I ...
- 21
5 votes
2 answers
350 views
High Speed Interfaces - Termination resistors vs Characteristics Impedance
I’m trying to understand the reasoning behind termination requirements in different differential signaling interfaces. For example, USB uses differential signaling (D+ and D–), but the standard does ...
- 1,821
2 votes
0 answers
51 views
Elmore delay equivalent for delay calculation [closed]
I am trying to understand the concept of Elmore delay calculating delay factor of the CMOS circuitries using RC approximation. According to CMOS VLSI Design : A Circuits and Systems Perspective ...
- 355
9 votes
4 answers
2k views
In a seven segment display, why does my "6" looks like a small letter "b"
I have made this circuit on Proteus, a simple BCD to 7-segment display: But the segments for 6 and 9 are not completely lit. What could be the potential reasons? The decoder IC is CD4511 and a common ...
- 109
-3 votes
0 answers
27 views
Parallel Bus interface on SOM module [duplicate]
I have this SOM module. I initially planned to boot the SOM module from a NAND Flash IC that uses a parallel interface (requiring address, clock, enable, and data signals). According to the datasheet, ...
- 1,821
1 vote
2 answers
81 views
Invert output from PCF8574 using a SN74HC05N to drive a 2N7000
Circuit design using PCF8574, SN74HC05 and 2N7000 I (a hobbyist) would be glad if you can help me with following: I want to switch multiple external relays. In lack of ports, I decided to use the ...
- 13
0 votes
1 answer
84 views
Propagation delay in a ripple carry adder depends on the bit pattern
Please help me understand how propagation delay changes depending upon the input bit pattern in a ripple-carry adder. Take 2 cases: 100+011. here no carry generated or propagated 001+111. here carry ...
- 13
3 votes
1 answer
79 views
Confused Between PTL and CMOS Implementation in OR(A,B,C) Logic
I’m a test checker for an Introduction to Digital Electronics course, and I’m currently reviewing student tests. The students were asked to implement the logic function OR(A, B, C) using PTL (Pass ...
- 335
2 votes
3 answers
463 views
Design a system that receives X and X+2 as inputs and outputs X+1, without using adders or subtractors
I was asked to design a digital system that receives two inputs: X and X+2, and must output X+1, without using any adders or subtractors. (We weren't told what is the number of bits for X and X+2) I ...
- 335
3 votes
3 answers
321 views
3 or 4-digit BCD to binary converter [duplicate]
While working on Digital logic, I encountered the problem of using a BCD switch to enter a binary number. For example, using a BCD switch, I can enter the number 117, which would be inserted into the ...
- 33
2 votes
3 answers
304 views
Can I provide ADC's DVDD to power other digital components in the pcb
I am using AD5941 in my design. AD5941 AVDD and DVDD are powered separately using two regulators . Same LDO P/N is used.One for powering AVDD and the other for Powering DVDD. In my board, I have ...
- 4,047
0 votes
1 answer
67 views
Why are pull-up resistors provided on the UART lines of the AM62L EVM?
I was reviewing the AM62L EVM (Evaluation Module) schematic and noticed that the UART lines (TX, RX) have external pull-up resistors to 3.3 V. However, when I checked the AM62L datasheet and technical ...
4 votes
2 answers
172 views
NMOS and PMOS in a series with VDD as voltage source, what will be the voltage between them?
I have an argument with a friend regarding the voltage between N and P and the voltage at OUT. I say that for A = '1' and B = '0': If Kn > Kp, so the voltage between the NMOS and PMOS is Vdd-Vtn ...
- 335