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.

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Precise multi-point over-temperature control using comparator

This circuit will (hopefully) send a signal to MCU if over-temperature is observed in any of the NTCs. Using LM339 as comparator, and a reference voltage (from TL431), assuming high precision for NTC ...
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497 views

Buried zener voltage reference: noise vs temperature

Buried Zener voltage references like LTZ1000A are known for their low-noise. High stability of reference voltage is often improved by temperature stabilization at somewhat elevated temperature. I ...
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49 views

Voltage drop by reference voltage generated by zener diode

I am now designing a circuit looks like this: simulate this circuit – Schematic created using CircuitLab My goal with this circuit is to compare the input digital signal with a reference signal ...
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37 views

AD7190 noise performance calculation

I'm using ad7190 to sample single-ended voltage. The rms input-refered noise is given by the datasheet. However, the datasheet only specified the noise with 5V reference, whereas I'm using 4.096V ...
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1answer
118 views

Reduce 2.503V regulated voltage by just about 3mV

I have a handful of REF192GP reference voltage sources. They are specified to produce a relatively precise 2.5V. Measuring each device I typically get a few mV higher than 2.5V, for example 2.503V. ...
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1answer
39 views

Ground Reference for multi layer board

I am currently designing a multi-layered PC board and there is situation where signals are referencing the ground plane meant to be used for the 3.3v supply. So, for example. I have a 3.3v plane on L8 ...
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41 views

Voltage reference output impedance calculation

I'm using AD7190 to sample 4ch single-ended signal. The datasheet suggests ADR431 or ADR421 as voltage reference for AD7190. However, an article on Analog Dialogue gives a way to calculate whether an ...
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1answer
74 views

How to feed reference voltage for two op amps inputs with different input signal each one

Im building a Stereo Buffer and a Baxandall circuit together. In powering the circuit with a single supply of 9v, and i need to bias each four inputs with 4.5 volts. The question is: If i feed the ...
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1answer
30 views

Beginner Question: Get 2 Reference Voltages for Comparator using Voltage Regulators

I'm working on a project where I have a 12 V voltage supply. I need reference voltages of 4.5 V and 3 V which will be each be used as the Vref for a comparator. I am aware that I shouldn't use a ...
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43 views

Fixed voltage drop (current and temperature independent)

simulate this circuit – Schematic created using CircuitLab Is there a clever way to create a fixed voltage drop say 2V that is not affected by current or temperature? Voltage stability should ...
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1answer
80 views

Precision reference voltage: buffering with OpAmp and BJT

I'm designing a reference voltage generator for the analog section of a circuit. Two voltages as needed: Vref = 3 V for ADC Vref/2 = 1.5 V for signal conditioning circuits (with a load of about 40mA) ...
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1answer
64 views

Level shifting with a voltage reference of 1.6V

I am trying to build a level shifting circuit for my project in order to make sure that the input will be appropriate for a 0-3.3V ADC. I am using two 9V batteries connected in series so my thought is ...
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48 views

Does reference voltage long term drift reset after a power cycle?

I'm building a 16-bit ADC system to measure the analog output of an ASIC and accuracy is of utmost importance. One subcomponent required for any ADC system is the reference voltage. When choosing a ...
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57 views

How does this voltage-reference circuit works [duplicate]

I have been trying to understand how this circuit works for the past few hours, it is supposed to be a voltage reference circuit that uses a zener diode, I am supposed to derive an expression for Vout ...
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49 views

KA336 replacement parts

Can you replace a KA336 with a TL431 directly? I have a circuit board with a broken KA336 and I can't find it here in my country, not even the LM336. It is a 2.5V shunt regulator. The adjust pin on ...
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1answer
95 views

TL431 - negative and positive references point

I am a musician who likes to play around with electronics. For some synthesizer circuits I am working on I need to create two references points using the TL431 - one for negative 2.5V and the other ...
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1answer
81 views

Digitally variable zener diode reference

I'm trying to use a digital signal (3.3V or 0V) to set a voltage reference for a comparator (4.7V and 6V.) I've come up with the circuit below but it doesn't seem to be very precise and I can't seem ...
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50 views

1.6v voltage reference with an input of 9 volt

I am trying to find a voltage reference with an input of 9 volts. I was able to find two from maxim integrated but had a max input of 5v. I was trying to find a fixed 1.6 output but I wasn't able to ...
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1answer
93 views

Virtual ground vs voltage reference

I want to know what is different between voltage reference and virtual ground and can you use both of it as rail-splitter in transimpedance amplifier, if not why. All I know is Virtual ground chips ...
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31 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 ...
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1answer
59 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
463 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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32 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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218 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
93 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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44 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
41 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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76 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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39 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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70 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
105 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
67 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 ...
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1answer
108 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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61 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
120 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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297 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
228 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
95 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
313 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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2k 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) / ...
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2answers
61 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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1answer
565 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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234 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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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 ...
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0answers
50 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 ...
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2answers
200 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 ...
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1answer
39 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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33 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 ...
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1answer
58 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 ...
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3answers
119 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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