cmos 74hc debounce pull up resistors

Started by usao in sci.electronics.design10 years ago 22 replies

I am looking to use a SPDT switch (center GND) with the NO and NC contacts wired to the inputs of a 74HC00 CMOS NAND gates. Is it necessary to...

I am looking to use a SPDT switch (center GND) with the NO and NC contacts wired to the inputs of a 74HC00 CMOS NAND gates. Is it necessary to tie both (NO and NC) inputs to power through a pull- up resistor? I have seen this done on TTL circuits, but I thought that the inputs on the CMOS had such high resistance that it would not be necessary. Yet, I also read in many places that the inputs ...


CMOS opamp 18V+, RR in and DIP-14?

Started by Joerg in sci.electronics.design2 years ago 26 replies

Gentlemen, Got an EMI (susceptibility) situation, existing design from a vendor, no major changes possible at this point other than 1:1...

Gentlemen, Got an EMI (susceptibility) situation, existing design from a vendor, no major changes possible at this point other than 1:1 component swaps. It's a quad DIP-14 in standard pinout. Bipolar right now which is EMI-prone so it has to be CMOS. JFET amps are out because we need the input range down to the negative rail and they can't do that. CMOS for 18V and higher is slim pic...


Error message on GPIB program, Help

Started by amdx in sci.electronics.design3 years ago 33 replies

Hi all, Recap- I had the low Cmos Clock Lithium Battery in a computer. I received a Cmos Clock Lithium Battery from China, had some question...

Hi all, Recap- I had the low Cmos Clock Lithium Battery in a computer. I received a Cmos Clock Lithium Battery from China, had some question about the date code. I installed the Cmos Clock Lithium Battery and had the same message low CMOS battery. I order a new one from Mouser and the computer now works properly. Now I'm onto making the computer control some HP equipment via GPIB, whi...


CMOS process at lower voltage?

Started by o pere o in sci.electronics.design5 years ago 9 replies

This is a basic question on CMOS processes. Given a fabrication process that is labellled as "1.8V process", is it possible / advisable / etc to...

This is a basic question on CMOS processes. Given a fabrication process that is labellled as "1.8V process", is it possible / advisable / etc to have a design work at _lower_ voltages? If simulations, for instance at 1.2V show up OK, is there any risk? Pere


CMOS Divide by 5.9 Cicuit

Started by Ken Knowles in sci.electronics.design3 years ago 27 replies

I have a CD4060 that uses a 32,768Hz crystal to generate a 32Hz square wave. I would like to divide this down several times in 5.9Hz...

I have a CD4060 that uses a 32,768Hz crystal to generate a 32Hz square wave. I would like to divide this down several times in 5.9Hz increments, while keeping the duty cycle at 50%. What would be the most straightforward method, preferably keeping in CMOS? Ken Knowles


Why Hasn't This Been Done with Silicon Carbide

Started by John Savard in sci.electronics.design3 years ago 58 replies

Today's microprocessors are all made using the CMOS logic family. It has the advantage of using a minimum amount of electricity, since -...

Today's microprocessors are all made using the CMOS logic family. It has the advantage of using a minimum amount of electricity, since - exce= pt for leakage currents, which are becoming more important as transistors a= nd wires shrink - electrical power is only used during changes of state. However, the performance of CMOS circuits is limited by the slower P-type F= ET branch of them - t...


CMOS OpAmp Design

Started by Anonymous in sci.electronics.design9 years ago 8 replies

Hi, I was looking for a CMOS OpAmp circuit which doesnt need need any special Common Mode Feedback circuit for stabilizing the bias...

Hi, I was looking for a CMOS OpAmp circuit which doesnt need need any special Common Mode Feedback circuit for stabilizing the bias point. Anybody has come across a circuit like that ? Please let me know regards Jean


Query about designing a linear amplifier using CMOS inverter

Started by Mandar in sci.electronics.design10 years ago 2 replies

Hi everyone, Here I have a problem in using CMOS inverter as an amplifier. What should be the consideration while choosing the resistance...

Hi everyone, Here I have a problem in using CMOS inverter as an amplifier. What should be the consideration while choosing the resistance value of the feedback resistor? I very well know that, it should be of order of few megaohms, but how many megaohms? Please help. Thank you.


Using CMOS logic for amplifying small signals

Started by Mr. B in sci.electronics.design10 years ago 16 replies

Something has occurred to me, and I was wondering if anyone knew more about this. Could a CMOS logic inverter, like a 4049, be used as a very...

Something has occurred to me, and I was wondering if anyone knew more about this. Could a CMOS logic inverter, like a 4049, be used as a very high gain amplifier if it were properly biased? I figured that the DC offset should be set at just about half the supply voltage, so that the gate was always between a '1' and a '0'. I am not sure if the gate would behave linearly in that region, or...


CMOS for driving MOSFETS?

Started by Jon Slaughter in sci.electronics.design9 years ago 5 replies

Why not use smaller mosfets to drive larger mosfet gates? One could put them in the same package so that logic level signals could be used to...

Why not use smaller mosfets to drive larger mosfet gates? One could put them in the same package so that logic level signals could be used to drive large mosfets? I'm thinking of implementing that idea discretely but maybe there is a reason for it? (although its going to cost me about 2x the # of transistors but its a clean switch) I imagine that one probably could cascage cmos stages i...


CMOS checksum fails

Started by Skybuck Flying in sci.electronics.design2 years ago 31 replies

Not sure what could be causing it. Seems to happen after power loss... and hard reset... also after weird electrical problem which happens...

Not sure what could be causing it. Seems to happen after power loss... and hard reset... also after weird electrical problem which happens rarely, which is solved by full power down, disconnect of cables etc. After saving settings and exiting bios, PC works as normal. Checksum error indicates some bits flipped ? What exactly is checksummed for CMOS ? Bye, Skybuck.


Meaning of "dynamic clock"?

Started by Tim Williams in sci.electronics.design9 years ago 6 replies

What does it mean when a processor has a dynamic clock? 8086 for instance. I notice, also, that many chips are (or were) available in HMOS and...

What does it mean when a processor has a dynamic clock? 8086 for instance. I notice, also, that many chips are (or were) available in HMOS and CMOS, and the CMOS versions were static (could be clocked arbitrarily slowly). Why the difference? Also, what happens when you clock something too slow? Does it start skipping beats? Does it lose data (internal dynamic RAM perhaps?)? I pre...


TS555IN question (CMOS timer)

Started by M Philbrook in sci.electronics.design2 years ago 7 replies

We have a remote signaling device that operates from a 3.2V battery source using a CMOS version of the timer.. ...

We have a remote signaling device that operates from a 3.2V battery source using a CMOS version of the timer.. http://www.st.com/web/en/resource/technical/document/datasheet/CD0000089 3.pdf At random and I mean very random, the circuit may need a power cycle. I was able to probe it while in a failed state and it appears that the chip could be latching? The only input t...


Mixed-Signal, Bipolar vs CMOS

Started by Jim Thompson in sci.electronics.design7 years ago 26 replies

Mixed-Signal, Bipolar vs...

Mixed-Signal, Bipolar vs CMOS.... http://electronicdesign.com/tabid/57/default.aspx?topic=three_industry_leaders_track_analog_chip _trends&catpath=&fltrTitle=&fltrSummary=&fltrPublication=?nl=1 ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | |


Feedback resistor in CMOS Xtal oscillator.

Started by pimpom in sci.electronics.design7 years ago 14 replies

I'm experimenting with a 32.768kHz oscillator using a watch crystal (no specs) and a CMOS inverter. The current limiting resistor is 330k and...

I'm experimenting with a 32.768kHz oscillator using a watch crystal (no specs) and a CMOS inverter. The current limiting resistor is 330k and the caps are both 15pF. It oscillates with 4.7-10Meg feedback resistor but not with 3.3M. I increased the Rf in steps from 3.3M and it reluctantly starts up with 3.8M, taking about 2 seconds to build up to full amplitude. Do you think 4.7M will b...


inverted cmos?

Started by Jon Slaughter in sci.electronics.design9 years ago 12 replies

I need to use cmos + invert the signal. I tried to put the nch mosfet on top and the pch on bottom. This does work except the output does not...

I need to use cmos + invert the signal. I tried to put the nch mosfet on top and the pch on bottom. This does work except the output does not swing rail to rail. I assume this has to do with the finite resistances in the mosfets? I think it will work for my app because I have a few volts to spare on my rail and these will be driving a power mosfet. My rail is 12V so I'll still get prett...


About CMOS Sensors SNR estimation

Started by kyori in sci.electronics.design9 years ago 8 replies

Hi, I wonder how to calculate the Signal-to-Noise Ratio with the datasheet of a CMOS sensor? I calculate the total excited photons...

Hi, I wonder how to calculate the Signal-to-Noise Ratio with the datasheet of a CMOS sensor? I calculate the total excited photons (Signal_N) from the irradiance, conversion gain and quantum efficiency. But, I am confused with the noise estimation. The datasheet gives, Parameter Specification Remarks FPN


Silicon CMOS oscillator at 430 GHz

Started by Jan Panteltje in sci.electronics.design10 years ago 1 reply

Silicon CMOS oscillator at 430 GHz http://www.sys-con.com/read/497124.htm

Silicon CMOS oscillator at 430 GHz http://www.sys-con.com/read/497124.htm


Mixing 4000-series CMOS and 74HC in a 5V system - any issues?

Started by Steve Goldstein in sci.electronics.design5 months ago 29 replies

Do 4000-series CMOS inputs have any problems coping with the much faster edge rates of 74HC outputs? Everything would be running on 5V, of...

Do 4000-series CMOS inputs have any problems coping with the much faster edge rates of 74HC outputs? Everything would be running on 5V, of course. It's all "just" digital logic, but sometimes the transistors inside forget that... And yes, I know I could use a processor and write code instead of using a few packages of random logic. That's not my desire.


Cmos Battery/Clock

Started by amdx in sci.electronics.design3 years ago 23 replies

Well I've received my M48T86PC1 Cmos Clock Lithium Battery as a gift from China, according to the custom declaration. It is an ST...

Well I've received my M48T86PC1 Cmos Clock Lithium Battery as a gift from China, according to the custom declaration. It is an ST microelectronics part, my concern is the manufacturing date. The Chip is labeled as below, M48T86PC1 Real-Time Clock Contains Lithium Cell 990SN VH MYS 99 1033 WO723Y I hate s...