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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40 views

How do I determine what range (not necessarily value) of resistors to use for voltage dividing [duplicate]

I'm getting back into electronics as a hobby and doing some refreshers having been away from it for a long time. I understand Ohm's law and voltage dividing, however, I'm not sure I understand what ...
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150 views

Is there any use of a 65 mV reference voltage?

I am a senior studying electronics, and have happened to make a bandgap reference circuit that gives out an output reference voltage of ~65 mV. I've constructed this after quite a few months of ...
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32 views

Voltage reference to drive multiple thermistors - high precision with op amp to supply current, or just generic voltage ref?

I would like to drive 8 thermistors in parallel. They will be driven from 2.5V in a voltage divider. This will be about 20mA current draw. I will be using a ratiometric measurement where the ADC ...
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1answer
41 views

Is the LM399 Temperature coefficient with the heater on or off?

The LM399 datasheet specifies a temperature coefficient "\$\Delta\$T/\$\Delta\$Temp". The conditions state an ambient range but don't specify if that's with or without the heater on. Which ...
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1answer
103 views

Why does my output get supercompensated?

I have almost finished a project that was supposed to output a square wave signal with a certain frequency but when I tried to make a small change to the circuit something weird happened to my output. ...
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105 views

Can't understand how the Zener voltage reference works

I've built a small amplifier circuit in which I've wanted to use a Zener diode as a reference but I can't figure out how it works. Knowing that the negative rail is -5V and the Zener breakdown ...
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41 views

LM4040 Shunt Voltage Reference Functional Diagram Explanation

Could you help me understand how this shunt voltage reference circuit operates? Cathode connects to Vin while Anode typically connects to ground (unless floating). This circuit is from the LM4040 ...
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3answers
1k views

Need help understanding schematics in LT1019 datasheet

We are currently using AD7795 to get ratiometric reading of 4 load cells. It works, but the chip stocks are rather volatile. So, I am thinking on using much cheaper and easier to come by MCP3424/...
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1answer
51 views

Standard approach for a split power supply ADC?

I'm currently working on a project that will incorporate an AD7124-8 ADC, which as far as I understand can accept true bipolar inputs when provided a split supply. I tried to dig around for an app ...
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52 views

Measure ATmega168PA internal temperature while using other ADC channels at 5V reference

I have a device that continuously measures the value of 3 sensors connected to 3 ADC pins and working at 5V reference, so I have two options for voltage reference selection: Connecting AREF pin to 5V ...
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161 views

Powering an op amp from a Reference voltage?

Let's say I had a low power op amp (pre-amp stage) going to an ADC (LTC2412). My question is: If I wanted a super precise, low noise, low TC drift, positive supply line could I just power the +A5V ...
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139 views

How do I use a Zener diode (LM4040) shunt voltage reference?

I would like to place a voltage reference for my MCU ADC. This is my first time using voltage references. I have chosen is the LM4040. It is relatively cheap and pretty good. I am getting the 3V 0.2% ...
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Reference input current value for TL1431CL5T voltage reference

There appear to be some mismatch for Iref value between the table and the graph for part TL1431CL5T. In the table it specifies the maximum value as 3uA where as in the graph it specifies as 1.7uA at -...
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96 views

Minimum voltage reference for ADC

I am looking to measure very low voltage signal (0-0.5V range) and was wondering if it is possible without amplification. I am a bit confused about what the minimum references of ADC can be. Looking ...
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Dificulty deriving voltage reference ripple

I have this voltage reference circuit and I need to derive the equation that gives me the influence of \$\Delta\$Vio on the output Vref which is my Vo, I have derived the equation for Vo when \$\Delta\...
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117 views

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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584 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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1answer
50 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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44 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
120 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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44 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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65 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
79 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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37 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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49 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
98 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
85 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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1answer
65 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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2answers
66 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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53 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
141 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
87 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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54 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
149 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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32 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
104 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
609 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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1answer
456 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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122 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
50 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
44 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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97 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
41 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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86 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
147 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
80 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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153 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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75 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
184 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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404 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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