All Questions
65
questions
0
votes
1
answer
718
views
CMOS vs TTL power and impedance
I need to compare and contrast a CMOS IC with a TTL IC. I've chosen a quad 2 input NAND gate IC, 7400 for the ttl version and 4011 for the CMOS. I'm having a bit of trouble with 2 of the requirements.
...
- 21
1
vote
0
answers
2k
views
LTspice - how to simulate real TTL gates?
I am trying to make simpler more general questions that might have more generally useful answers.
If you build a mixed analog digital circuit then you need to have models of real TTL or CMOS gates ...
- 1,541
0
votes
1
answer
39
views
Safety considerations (for parts) for a beginner building with expensive parts
I'm building for the first time (for me) a circuit with an expensive part (a $80 DEC J11 CPU) and would like to know some "safety" tips so I don't inadvertently destroy the thing while playing with it....
- 101
5
votes
1
answer
1k
views
pull-ups between logic gates
I'm trying to understand why, on this circuit bit, they used pull-ups resistors between logic ICs of the 74LS and CD4000 families. Specifically I'm talking about resistor array RM1 and R1. All the ICs ...
- 511
0
votes
1
answer
88
views
Are there combo gates XOR followed by AND? (4-bit identity comparator)
Is there no 4 bit identity comparator in TTL or CMOS? It could fit into a DIP-12 package as all it would have is 4 XOR gates for selectable invesion and 1 4-way AND gate.
OUT := (A1 xor B1) and (A2 ...
- 1,541
0
votes
0
answers
2k
views
Deciding between ULN2804 or ULN2803 with 74HC595
I'm making a circuit with Arduino + 74HC595 + (ULN2804 / ULN2803) to drive a few 12 V Motors.
I'm trying to decide whether to use the ULN2804 or ULN2804. On testing, performance of both is fine, ...
- 11
11
votes
2
answers
1k
views
Does this circuit have marginal voltage level problem?
As a research for the problem I described here I found this circuit by Maxim:
This is clock doubler, and must be a really good fit in my case as input frequency is very well defined.
However looking ...
- 7,120
0
votes
1
answer
2k
views
STM32F407 CMOS or TTL or HC
I wonder which logic technology is STM32F407 MCU based on.. CMOS or TTL or HC or LVT etc? Although its mentioned in the datasheet that the GPIO's are CMOS and TTL compliant. I am concerned about this ...
- 907
0
votes
2
answers
4k
views
What is the point of 2 inverters in series? [duplicate]
In the datasheet for the Nexperia HEF4543B, in the logic diagram, there are 2 inverters in series:
What is the point of these inverters in series?
- 662
2
votes
3
answers
631
views
74AS TTL to CMOS pull up resistor and maximum speed (or lowest delay)
I have to pilot a CMOS input 5 V chip device with a 7474 flip-flop with the lowest possible delay to minimize clock jitter. The signal is about 11.3 Mhz.
I have two options:
74HC74 (CMOS compatible) ...
- 461
0
votes
1
answer
384
views
Replacing CMOS SRAM with equivalent TTL SRAM
I want to replace an IS62WV51216BLL-55 (http://www.issi.com/WW/pdf/62WV51216ALL.pdf) with an AS7C4098A-12 (https://au.mouser.com/datasheet/2/12/as7c4098a_v1.2-1288279.pdf), as the latter has much ...
- 137
10
votes
2
answers
2k
views
How to manufacture chip on board?
I am a developer of a cheap product and i have no experience in mass production. Device is fully functional and represents a single sided PCB, a microcontroller, a bunch of diodes and a few passive ...
- 340
0
votes
1
answer
261
views
5V to 3.3V Converter
I have a problem in connecting Raspberry PI to an MCP3202. I am using MCP3202 at 5V and knowing that raspberry pi works on 3.3v. I have found a solution to convert from 3.3V to 5V using 74HCT244.
And ...
1
vote
2
answers
410
views
what logic family does tri state logic fall into?
Here is a good Wikipedia on logic families.
This seemed like a particularly important line.
Of these families, only ECL, TTL, NMOS, CMOS, and BiCMOS are
currently still in widespread use.
I'...
- 335
0
votes
2
answers
124
views
Are D flipflop inputs and clock thresholds the same for a given logic family?
I'm using an SOIC20 74ACT574 octal flipflop in a design.
Vcc is 5 V, and GND is 0 V. The datasheets give V_IH (logic high input, guaranteed minimum) as 2.0 V and V_IL (logic low input, guaranteed ...
- 1,104