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48 Threads found on Adc Negative Input
Hi, Here is the problem I have. If I have a near square wave signal biasing at 0V with +-3V and this signal is feeding into adc with reference voltage 0 to 3.3V. What I interest is the only peak magnitude value of square wave (the negative part is actually not interested). Can I do so? Will this negative part signal will affect the circuit (...)
Did you bias the 1V pk-pk signal around 1.65V? Your signal is well within the +/-1.25V range of the adc input. I also suspect you are interpreting the data wrong and it is the negative side that is missing, I'm not going to check but I would imaging that the adc uses a 2's complement output. Well I checked anyway (...)
by using difference amplifier will there be any adc value loss Applying 5V reference will necessarily result in not fully utilizing the adc range with 5V rail-to-rail OPs. Using higher OP supply voltage brings up a problem of violating the adc input voltage range. Best solution is probably a slightly lower Vref, e.g. 4 or (...)
Hi, I'm not getting the right voltage What can we know fro this infirmation? * is the result negative, positive? * is it too higb or too low? * does it differ 100% or 1% or only 0.01% --> the only way is to read the adc's datasheet. It telks you all you need to know. There are so many different adcs with so many different (...)
The maximum output of 5V is made of 2^ 12 steps, so a signal of less then one step will not produce an output. If you are measuring AC, then in the absence of an input signal you have to bias the input to + 2.5 V, so the input can go positive and negative from this value. Also the adc works on the peak (...)
please suggest any pic ic that has differential adc inputs
Hello, YES ! Resolution = Vref/ N bits adc more datas ! the specsheet of adc
Your negative voltage has two wires, a negative output and a common output sometimes called "ground". If the circuits are not earthed then if you simply swap the wires then the negative wire can be the common input to the adc and the common wire can be a positive voltage input to the (...)
Hey Guys I need to be able to read voltage readings from 9V - 20V and from 70V - 140V with a Atmega 168 5V adc input. Now ive tried the simple resistor divider but because im a really cautious person, I really do not like the idea of high voltage NOT being isolated from my MCU. So ive looked at some circuits with Op-Amps. Problem with the Op
Hold the Phone.... "RF devide" you mean RC divider. this adc does not do RF..... 200 kSPS is max
Hi y'all, I have a converter that is designed to output a -100V but now I find it challenging to read that on adc. My first approach was to use an inverting amplifier with a gain of 1, the problem is that i'm not sure if the op-amp will be able to handle 100V because most of the amplifiers are rated at low voltages. Can anyone help me on this. Tha
C5/R15 will cause malfunction of the circuit. negative halfwaves are clipped by the input protection diode of the adc input. The most simple solution is to omit the highpass, send the 2.5V centered AC signal to the adc and process it in a suitable way. If you want to convert the AC current to a DC voltage (...)
Surely the voltage divider will not treat positive and negative half cycle differently. I rather guess you didn't describe your setup well and have additional components connected to the voltage divider output. If you e.g. connect it to a 0-5 V adc input, the negative half cycle will be cut because it exceeds the (...)
This Source degeneration Gm-cell with negative-impedance-compensation(NIC) technique is used to design loop-filter for 2nd order Sigma Delta adc. I dont know what are the parameters/specifications needed for the design of the adc. Also i need input parameter values like Vsin, Vref, Vss for this Source-degeneration Gm-cell. (...)
No pins of 8051 can accept analog voltages. So you need an adc converter. If it is a matter of reading the applied voltage only, then why don't you rectify the supply. This way you can rule out the negative half cycle... Use a rectifier & a good filter, convert it in dc, read through adc, multiply by 44( if step down is 220v - 5v) & divide (...)
hey I am using max1415 adc in differential input mode. maximum Differential input i am having is 4 volt p-p sine wave (ie 3- (-1)). datasheet of max1415 tells me that max vref i can get (which is ref+ - ref-) is 1.75V. Now my que 1. since I can have -1V input at one pin does that mean i need to have atleast -1V at ref-? or (...)
Hello , I am doing Image acquisition using Analog devices AD9643 Digitizer and HSC EVAL C Data Capture Board. I have 71 Khz low freq input square pulse ( +5 Volts and 0 volts TTL wave ) and clock square running at 100mhz. When I get the waveform using the software I see it looks like it is not pure signal anymore , it has negative parts like
HI guys, the thing is that i want to read pc speaker line out which is an analog volt signal using PIC adc I Don't know anything about this i have project in which i must read speaker line out from pc and compare the voltage values with the same portion of signal that will be send to amplifier so it's one signal out from pc and in to ampli
I have pointed to a thread that shows how to add in offset in a negative signal in order to make it positive and feed the adc input. It doesn't matter is you have a constant negative voltage or an AC voltage, the point is that you have to get rid of the negative voltage. But I am using DC 12V, Where does (...)
Hi, I'm trying to sample readings from a strain gauge using Arduino. I have a RS strain gauge amplifer which allows me to adjust the excitation voltage and adjust zero point with variable pot trimmers. The signal is amplified by 1001 for instance and an output signal is given. I want to be able to measure both tension and compression using a adc
You need to calculate the resistor ratios for correct gain and care for keeping the AD8138 permissible input voltage range. VCOM is solely commanded by the required adc common mode voltage.
Thanks for the reply. Actually the inamp is part of an adc (AD7793). From the datasheet it says that the common mode is required to operate the device properly. I was hoping that the provided circuit would make it easier to explain the problem ... Still any advice ? Regards Peter
Hi.. One of the signal which is ( -3.3V to 0 ) need to clamp to level of 0V. I can do that using the level shifter by using a voltage divider pulled up to Vref; but need to implement some other technique. Basically I want to block (-3.3V to 0 ) range to adc and allowing only ( 0 to +3.3VDC) signal to process. adc is referenced to +3.3VDC and
I'm trying to input laptop's 3.5mm audio signal to pic18f452 adc, but I'm not sure what kind of ac voltage that plug outputs... I assume that would be something like -1,0V to 1,0V, also I've heard that negative reference voltage can't be below zero. So I'm planning to use a summing amplifier
Hi, I need to sample an analog AC signal ranging between -0.1V to 0.1V. I will take the digital ouput to an fpga, however Im having diffuculties in choosing the right adc, since nearly all of the ones I looked act as if they accept only positive voltages in single ended operation and choosing a negative input to V- in differential (...)
If the allowable voltage is +5V for the adc then you may use a voltage divider to bring down the 0 - 10 V to a suitable level like 0 - 5 or 0 - 4.5V as per requirements. If 8 bit resolution is insufficient then you may go for a 10 bit or 12 bit adc.
Hi All, I am designing a 10-bit pipelined adc with an on-chip sample and hold amplifier that operate at 40MHz with a power supply of 3V. I don't kown the relationship between INL and the output residue of each stage. For example, when I simulate the pipelined adc, which is differential input. The positive input is 2V, (...)
when the input will have the same voltage as the vref value the output will be all 1s (this depends on the adc and if it supports negative values). In general for a 10 bit adc you have 1023 different values so each step will be vref/1023 for example if vref=5v then 5/1023=0.0049v so if the input is (...)
Hello, I need a pcb design for a microcontroller (89c51) which is interfaced to a keypad, LCD and adc804 whose input is connected to an adder ckt to taken in the negative voltages.. Some one plz do help me cause i am really new to all this ..:)
I am doing a microcontroller (89c51) based project and the peripherals used are adc804, LCD and a keypad. The input to the adc is both negative and positive voltage so does anyone know how can u make adc read a negative voltage. Some of my friends told me that i can add an (...)
1.4 V is full scale input of my adc. Your dBFS value = 20*log(voltage/dbFS-voltage) , i.e. below 1.4V always negative: voltage dBFS value 1.3V -0.64 dbFS 1.2V -1.34 dbFS 0.7V -6.02 dbFS 140mV -20 dBFS 100mV -22.9 dBFS
Hi. A differential adc has a positive (Vin+) and a negative (Vin+) analog input. These inputs require two equal drive signals that are 180° out of phase. The amplitude of each drive signal should equal the reference voltage, Vref, of the adc to use the full dynamic range of the device. When a conversion (...)
Hi All: I am relatively new to 16 bits. My task is to sample an analog ECG signal from an ECG amplifier (0-3v analog). I am able to display the positive values of adc on LCD, but unable to adc/sample the negative going signals. Can anybody point me to sample code for sampling negative going signals. I am using (...)
in calculating the offset error of bipolar adc,whwther we need to take the first transission at the negative input or the deviation at the code zero
Does voltage on the reference input of this adc affects the result type of the output? Or it's not related to that. E.g there will be positive and negative voltages which will come from the loadcell to the inputs of this adc. There is a bit for the output type in the channel setup register (...)
Hello all, So I was wondering how to choose the reference voltage for the DAC in the sigma delta adc. Considering a 1.5V process the input sinusoid is centred around 750mV. With the quantizer levels of 1.5V and 0V what value do I need to feed back to the input. If I were to use 1.5 and 0V as feedback signal, I would get (...)
Hey Everybody, I had PIC works as adc and it works very well with positive voltages the problem is that I have to convert from A2D through the PIC negative voltages so what I did simple design of inverting amplifier which converts the negative voltage to positive voltage and the output of the amplifier connected to the (...)
Hi everone, I was wondering how one defines the required gain for a receiver when the signal SNR is negative, which is the case for example for spread spectrum coms. My current understanding is that knowing the system bandwidth, one can determine the noise power at the system input. Then knowing the adc full scale range, the gain can (...)
Hi every one . Can anyone help me how to design 4-20mA input (output of pressure sensor) to give me 0-5v output for adc.Because i want to read it in microcontroller. Added after 1 hours 14 minutes: I Need conditioning circuit using Op-Amp for this 4-20mA input to give 0-5v output f
i use opamp to convert 4 to 20mA to 0 to 5v output before input to adc brfore,so can u suggest any opamp without negative input,o any adc direct convert from current input to voltage need of an opamp. Use a 100ohms+150 ohms as a shunt to the 4-20 mA signal and feed to PICmicro. You will get (...)
please post your adc IC number so that we can have an idea on what you are actually talking about....
You must be very carefull. Your need a step down transformer (a 220VAC/5VAC), but also you need to avoid any negative voltage in your adc input. Please refer to: Measurement Systems: Application and Design Ernest Doebelin
Simplest - put resistive voltage divider with one side connected to stable voltage source second to your negative voltage output and middle to adc input directly or thorugh buffer . Choose division factor to based on min negative voltage and voltage source resistors connected to .
That is a very common issue since adcs are usually unipolar. Time ago I saw at Maxim website a simple but effective 3 Rs front-end solution which address your problem: adc input connected to a voltage divider from Vcc (2 Rs) and another R from there to your input (negative sometimes) choosing proper R values (...)
Hello, i am using adc ADS1602. For this differential input needs to be generated using THS4503 OPAMP. Can anyone help me to design this OPAMP circuitry with single supply? I dont ve negative supply on board. I want to make fully differential OPAMP to work in single ended mode. Niks
Hi, can 16F87X use +2.5 to be Vdd and -2.5 to be Vss ? Well, technically no. But......remember, A micro (or any voltage device) only really cares about voltage difference, theoretically you could drive the micro with VSS: -10v and VDD: -5v. So its powered with a difference of 5v. The only reason they are negati
There is always a chance of blowing a chip with to high or negative voltages applied to its inputs. Some 5V IC can withstand a couple of more volts and a small (between 0 and -1V) negative voltage, but if you use a small serial resistor (100Ω) and a 5.1V zener diode connected between adc input and GND (...)
Isn't the PIC adc a capacitive type? If so it'll accept negative inputs to the adc and you will have to tell (program) the adc that you want bipolar input.

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