Questions tagged [voltage-reference]
Anything related to the design and implementation of voltage references, i.e. circuits behaving like fixed (constant-value) voltage sources whose output voltage can be deemed very precise, accurate and stable. Voltage references are not meant to provide significant current to external circuits.
222
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27 views
Improve range on a differential ADC
I'm using an MCP3425 ADC, it has differential inputs but I'm using it as single ended mode.
The signal that I want to digitize comes from an integrator circuit (an op amp with a capacitor in its ...
2
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1answer
45 views
Level Shifting Circuit to output 0.2V-4.8V
Having a sensor's dynamic range from 4V - 10V, I am looking for a level shifting circuit using op-amp that gives me an output of 0.2V - 4.8V. I have been looking through many design yet I could not ...
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1answer
341 views
Bypass cap on reference voltage?
For a voltage reference providing a reference to multiple devices, ADC, DAC, instrumentation amp... would there be some benefit in placing bypass caps right at the reference input to these devices ...
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28 views
Moving from ICF in-amp to traditional in-amp, removing bridge offset, driving ref pin with shunt regulator
Right now im using AD8237 with MCP4725 to remove bridge unbalance. I'm using 3x 1k Ohm resistors and one strain gauge arranged in Wheatstone bridge.
My circuit looks like that:
It works perfect for ...
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1answer
78 views
How to modify TL431 current limiter to work with 80V bus?
I referred following circuit from TL431 datasheet
TL431 max voltage at cathode is 36V.
since circuit has only a transistor , how to modify this circuit to work with 80V at input(Vi bat).
output ...
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1answer
69 views
Does AREF pin of ATMEGA series consume any current?
I have a voltage reference in the circuit and I thought I can feed that reference to AREF pin of ATMEGA as well:
The current at "1.024V" tag is around 200 uA, any current drawn by the AREF ...
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1answer
32 views
Programmable sensor signal reference voltage
I'm designing the front-end circuitry for an ADC. The ADC is to be used to read from sensors under two use conditions:
An externally referenced sensor, whose signal line will either be 0-5V or ...
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2answers
36 views
Transformer isolation and reference
For testing purposes, I need two circuits: 220Vac rectified and 48Vac rectified, both having the same reference, like this:
But I don't have an isolated transformer 220V:220V. I only have an isolated ...
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2answers
65 views
Is this differential RC filter needed on a reference voltage?
What is the use of the differential RC filter at the end of this op amp (at least I'm seeing R100+R98+C28 as that)?
P3_3V_REF is a reference voltage for the 4 ADCs in the TMS320F28377D-EP MCU. An ...
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0answers
38 views
180V voltage reference
I have a 195-210V(with ripple) power supply and I need a 180V voltage reference.
This is my best idea so far:
Instead of just connecting a resistor and 180V zener diode in series, I do it two times ...
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3answers
53 views
Op amp to supply current to 3 thermistors and an ADC voltage reference input
I have 3 thermistors in parallel that I need to measure.
These thermistors will be fast changing - think up to 100C in under 1 second.
I want to do this ratiometric measurement, so I want to supply ...
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3answers
79 views
Vref value and Vref shunt ICs for an ADC
Hello i am building an ADC circuit, this is my first time building a proper adc that is higher performance. The adc is the ADS131
The ADC will be powered by an isolated 3.3v and I would like to know ...
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1answer
56 views
Powering TL431 from MCU output possible?
I'm designing a board with ATmega128 MCU. I have a TL431 reference connected to the ADC_REF pin, with both TL431 and the MCU connected to the same supply, 3.3 V.
Now I realized one problem - since ...
2
votes
1answer
56 views
Voltage reference voltage drop
I have two potentiometers and a single voltage reference, connecting them causes a few mV voltage drop in the simulator:
Adding an op amp solves the problem but then comes input offset voltage and ...
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0answers
47 views
Using a Zener to offset split rail?
simulate this circuit – Schematic created using CircuitLab
i've searched but can't find a definite answer, is it possible to use the standard resistor divider but with a Zener in the middle to ...
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2answers
85 views
Optocoupler Reference
I want to use in my project an isolated optocoupler like this one to switch an IGBT.
In the following schematic, taken from this Vishay application note there's a "floating supply" in Vcc1 as you can ...
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2answers
111 views
LED voltage references?
Often reference voltages are generated using normal LED/diode, not zener.
A reference from simple resistor divider will not provide any regulation of input voltage, a zener will provide regulation and ...
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1answer
85 views
What is ADC Supply Current in Microcontroller and how much current will a GPIO take
I am having this Microcontroller
In this Microcontroller, I am using the ADC peripheral and normal GPIO port.
My questions:
On Page 58, table 42, There is a parameter called as Supply Current per ...
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2answers
84 views
Poor man's voltage reference
I want to build a voltage reference based on LM4040 (A series 0.1%), the output voltage is switchable with a selector switch:
simulate this circuit – Schematic created using CircuitLab
...
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1answer
124 views
Voltage Reference Resistor Calculation (Shunt)
I am trying to design a circuit using this LM4040-5 Voltage Precision Reference for my DAC8554, but I can't for the life of me figure out how to properly calculate the resistor value to be applied. ...
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0answers
712 views
How to calculate RMS current from the rated current? Are they the same in a stepper motor?
I want to use the TMC2130 driver with the stepper motor I show below. This driver has these main features amongst others:
Integrated power MOSFETs handle motor currents up to 1.2A RMS (QFN package) / ...
2
votes
2answers
36 views
Noisy output on voltage reference and correct probing
I'm building a circuit that has a 2.5V Voltage reference for use on the internal ADC of a STM32F7 in 12 bit mode. As each bit corresponds to 610uV I'd like to have as little noise in the signal as ...
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0answers
26 views
Bipolar voltage reference for DAC AD5791
I am constructing a circuit utilizing the DAC AD5791 from Analog Devices. As shown in the application example in the datasheet, a bipolar voltage reference with +/- 10 V is needed. In fact, the ...
0
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1answer
187 views
When to add an op amp buffer to a voltage reference IC?
The circuit below is from a TI reference design, but my question is generic. I'm generating a voltage reference to add a DC bias to an AC signal for ADC purpose. Could I use the output of the voltage ...
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2answers
126 views
Voltage reference with op-amp buffer and additional filtering
I commonly see voltage references implemented with op-amp buffers as shown below. That's the simplest way.
However, see below another way of doing it which I found in a meter:
The second one seems ...
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3answers
8k views
How does this opamp circuit act as “good” voltage reference?
If I understand correctly, we are using MC1043 because we don't trust Vcc to be stable. I get that the output of MC1043 is 2.5V which is extremely stable.
But I don't get how the output of opamp ...
2
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0answers
46 views
TSM104W Voltage Reference
Hi I am trying to design with the TSM104W, which is a 4 package rail-to-rail OpAmps, with a built in voltage reference. This is the package pinout:
I see that the four Op-Amps are supplied through ...
1
vote
2answers
101 views
Hall Effect Shielding
The objective of the circuit below is to get the difference of the hall effect output and a 1 volt reference, then amplify it.
When I first built the sensor and tested it, it worked very well. This is ...
0
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1answer
34 views
Bandgap References - What's the need for a PTAT voltage if we can invert a CTAT?
I was reading up on bandgap references. I noticed that a CTAT voltage can be simply produced by taking the Vbe voltage of a BJT.
However, when generating the PTAT voltage, most books seem to mention ...
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0answers
31 views
Current mirror not depending on power supply (BANDGAP design)
is there any topology that allows a current to stay constant on a current mirror when the power supply of the transistor is varied?
I simulated a bandgap and the PTAT varies a lot when I the power ...
0
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1answer
45 views
MCP4725 DAC and reference volatge
MCP4725 has internal reference voltage which is equals to VCC:
VDD is the power supply pin for the device. The voltage at the VDD pin
is used as the supply input as well as the DAC reference ...
3
votes
3answers
111 views
Second Order Filter with DC offset
The circuit below takes the signal from a current transformer, depicted as I1, convert it to voltage through R9 and go to the second order filter U1. I want to add an offset to the current transformer ...
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0answers
31 views
Higher order effects of CTAT and PTAT when testing a BANDGAP
I want to use candence to simulate the real behavior of a voltage reference and so far I found circuits that are based on the ideal models.
What non linearities can I introduce in this ideal model ...
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0answers
36 views
Temperature coefficient of a voltage source
Is the temperature coefficient of a voltage source related to the internal resistance of the voltage source?
Why does the voltage increase/decrease when the temperature is increased or decreased?
In ...
0
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1answer
58 views
One voltage reference per DAC or one voltage reference for all DACs?
I have a circuit that requires six 18-bit DACs (AD5680) on it. Each DAC draws ~800µA at the high voltage output +5V and ~400µA at 0V output. Is there any issue with a single REF195 voltage reference ...
2
votes
3answers
79 views
Generate accurate 20mV Vref
I want to generate 20mV Vref using Op amp, like this:
When simulate with TINA using model from TI, instead of 20mV at output (Vref port), i see that it is 27.95mV.
My question is:
Why I can't get ...
1
vote
4answers
164 views
Does resistance decrease over a resistor?
If ohms law pertains to voltage, current, resistance across a resistor, in order for voltage to drop, and current to remain the same, does resistance drop as well across the resistor?
To explain what ...
3
votes
1answer
159 views
Grounding an audio signal
I'm building a simple audio mixer. It's going to be running from a USB power supply, so I'm using a TLE-2426 to derive a 2.5V reference voltage for the summing op-amp.
My question is, what do I ...
0
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1answer
72 views
reading a high negative voltage with attinys running on batteries
I need to read a negative input voltage from a camera flash capacitor that can charge up to -330V. I am using an attiny85V that is running on batteries and want to set the internal reference voltage ...
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1answer
277 views
Arduino mega 2560 Analog max reference voltage
Each time I power up the Arduino, the max reference voltage which is represented by 1023 changes. I observed this by measuring the voltage from the Aref pin each time. Is there any internal function ...
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0answers
79 views
How does one calculate output voltage noise of a current output DAC?
I am using a current output DAC connected to a voltage reference and a transimpedance amplifier.
I know the noise characteristics of the voltage reference and the amplifier. The DAC simply lists "13 ...
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1answer
146 views
In HLW8012 where should I connect the reference voltage (GND)
In the datasheet of HLW8012, the both 33nF capacitors , 1K resistor and 0.1uF capacitor are connected to GND. I'm not sure where should I connect those ends of components marked with GND symbol, (To ...
0
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1answer
301 views
STM32F030R8 Nucleo-64 Board ADC Voltage Reference
I want to decrease the reference voltage of the ADC to have a better resolution, by now I do not want to try other options.
Could someone explain me how can I do this?
I am using the Nucleo-64 ...
0
votes
3answers
786 views
What is voltage trimming in bandgap references?
I just started reading about bandgap reference circuits (PTAT, CTAT generation, etc.) in CMOS and I see a lot of papers about something called trimming in relation to these.
What does it actually ...
0
votes
2answers
130 views
Series voltage reference unstable with a series resistor
I am using the MAX6035 as a 5V reference that draws 5mA load current. To protect the input from transient spikes, I thought a simple resistor and zener diode circuit would work well. I noticed that ...
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1answer
63 views
Voltage on LM4140 Vout
I'm using an LDO called LM4140 with an op amp, where VREF is connected to the output of an Op-amp via a resistor network. As the op-amp will be outputting voltages from -10v to 10v, is there any ...
0
votes
1answer
218 views
Stable 200uA Current source by cascading REF200's Current source and Current mirror
I am trying to work on above circuit. A common operating point of ISFET pH sensor is a drain-source current of 100 uA and a drain-source voltage of 500 mV. I am using REF200 current source to feed ...
1
vote
1answer
207 views
How do I make a discrete voltage detector?
I would like to design a circuit which has outputs LOW when the voltage it is connected to is below a threshold, like 3.3V.
There are some ic's you can buy to do this, but I would like to make my ...
0
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1answer
211 views
LDO Voltage regulator output unexpected Voltage drop
I have a circuit using LD39015 1.2V Low Drop-out voltage regulator.
.
The value of VCC is 3.3 Volts. The goal is to supply an ADC channel with a constant stable voltage so I can use that to ...
0
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2answers
41 views
Determining equivalent resistance to find the cutoff frequency
I am designing a low noise circuit for a precision application and require a stable voltage supplied to the circuit. I have determined that the MAX6250 voltage reference best suits my circuit. A ...
