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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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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42 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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74 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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58 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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41 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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52 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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43 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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51 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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76 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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43 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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76 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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30 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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52 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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397 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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30 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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162 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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78 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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36 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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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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70 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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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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60 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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93 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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59 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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82 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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54 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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102 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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209 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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145 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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88 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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207 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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1k 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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46 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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40 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 ...
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362 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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169 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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49 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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151 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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37 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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53 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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117 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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34 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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38 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 ...
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63 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 ...
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89 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 ...
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189 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 ...
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221 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 ...
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75 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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