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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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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72 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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28 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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29 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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32 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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95 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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23 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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31 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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1answer
52 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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65 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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110 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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86 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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61 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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126 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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67 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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86 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 ...
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201 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 ...
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342 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 ...
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98 views

Powering and regulating supply DC voltage for a digital MEMS microphone

I want to use Infineon IM69D120 microphones [1][2] in an array (about eight of them), and I am confused as to how exactly (with which components) should the MEMS microphones be supplied. I chose USB ...
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98 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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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 ...
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151 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 ...
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158 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 ...
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158 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 ...
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36 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 ...
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221 views

Precision Adjustable Voltage Reference

Can a low-cost, low-resolution RDAC and a precision voltage reference by used to make a coarsely adjustable high-precision DC voltage reference? Consider for example the AD5121 7-bit RDAC with ±5ppm/°...
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44 views

switch 3 references voltage for my servo position

I have some positioning servo driver and servo with pot feedback. Now I try to build circuit to switch between 3 positions. For testing I just use 3 way switch and 3 pots as voltage reference, but in ...
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124 views

Using a voltage divider with buried zener voltage reference

My plan in the below circuit was to use a voltage divider from a Max6225 2.5Vref, to get 2V and 1V from it in order to use the full 16bit bipolar scale of the ADS1115s, but I'm getting strange ...
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174 views

DAC negative bias reference voltage

I'm using TI's 18-bit DAC9881 and need the output to go a little below 0Volts in order to account for offset voltages of following Op-Amp stages. The DAC allows to provide a "low reference" between -...
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77 views

How can I create a fixed voltage reference output voltage from a varying input voltage?

Suppose I have the following: A voltage source that outputs a voltage between 10 and 14 V. I need to generate a fixed reference voltage independent of the input voltage mentioned above. How can I do ...
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265 views

Reducing noise on a voltage reference

I need a stable, low noise voltage reference that I can adjust between 1.4V and 1.8V. The output should source or sink up to 0.25mA @150Hz max. The output will provide a +1.65V bias for a bipolar ...
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147 views

LM317 Vout drops on load

I built a very basic circuit to get around 5.5V from a +15V source I have a 220 Ohm between Adj and Vout and one 470 Ohm, one 220 Ohm and two 100 Ohm in parallel between Gnd and Adj summing up to ...
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515 views

Negative Voltage Reference for Bipolar ADC

I am considering using ADS1258 - a bipolar ADC. It needs an external reference across REFP(+) and REFN(-). How do I generate precise -2.5V assuming I have +12V and -12V analog voltage rails? I can ...
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227 views

Using positive voltage reference on a negative supply

Got a 9V,0,-9V power supply and want to get two stabilised voltage references at 2.5V and -2.5V. Is it possible to use a +2.5V reference chip "upside down" to supply the -2.5V?
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89 views

REF02 not working - 4 channel 5v DAC circuit, star gnd connection, stripboard layout

I've connected my circuit as in the diagram, with a 15V PSU powering it (both amps are connected the same way) - but the DAC seems to be drawing too much current for the REF02 to handle, even though p....
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720 views

Flip a Schmitt-Trigger when current flows through a Zener diode

I am trying to design a circuit using an intermitent power source (a bicycle hub generator), which is rectified and filtered, and regulated at 6,8V. Now I want to "detect" when the power source is ON ...
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1answer
136 views

build 2V reference with 100mA output

Consider I have a 2.048-volt reference voltage, for example, I build this voltage with REF191, this IC has only 10mA output current, How can I boost this current to 200mA? is there any better way to ...
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125 views

Voltage reference TLVH431

I started working with the LT1990 Differentiel amplifier. In the datasheet, it's stated that it needs a 1.25V voltage reference. I made some research and I found the TLVH431 Low-voltage adjustable ...
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296 views

Generate negative reference voltage

In my current design, I need to include force measurement. A301 sensor is selected for this. Now, in order to be able to have analog voltage proportional to the force applied, I need to have negative ...
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Why use 2.048V and 4.096 as a reference?

On many voltage reference ICs (As an example a MAX610x) there seems to be various different reference voltages available (1.25, 1.8, 2.5, 3.3 etc). What strikes me as odd are the 2.048V and 4.096V ...
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126 views

What's the PIC FVR's gain amplifier settling time when you change the gain

I previously had configured a PIC (16F1704) to use the internal FVR for ADC reference, with gain of the FVR set to 2x, i.e. 2.048V reference. I've since added another signal to be measured, but the ...
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42 views

Loading reference output of an ADC

My ADC (LTC2323, 16 bit, 5MSps, http://www.linear.com/product/LTC2323-16) has an internal reference (4.096V) which is provided at output pins REFINTx. Now I need (...
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463 views

Do the temperature coefficients of the resistors in the LM399/LM199 “Portable Calibrator” significantly effect the output stability?

I'd like to know how voltage reference stability is obtained in products like 6.5 digit multimeters that use LM399 as a voltage reference in spite of using two gain resistors. Let's assume an ideal ...
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674 views

Resistor Between Voltage Reference and + Input of Op-Amp? Why?

something I commonly see in schematics which include op-amps set up as inverting amplifiers is the inclusion of a resistor between the non-inverting "(+)" input of an op-amp and a strong voltage ...
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441 views

How an op-amp determines its output without a reference point? [duplicate]

I was struggling to understand how an op-amp determines its output without a reference point. The output of an op-amp is A * (Vni - Vi) Then let's say we have an inverting op-amp with a gain of 1000,...
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651 views

Is a diode's forward voltage stable enough to be used as a reference voltage?

Assuming a resistor is in series with a diode (say, a 1N4001) so that the diode has around 1mA of current, will its forward voltage be usable as a voltage reference to within 1% (relative to itself ...
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153 views

What are the critical characteristics of an op-amp for buffering reference voltages?

So, let's say I have a precision voltage reference with the output fed to a voltage divider which is tapped at two places for voltages A and B. I've made sure to use precision resistors (or calibrate) ...
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215 views

ADC Vref Options [closed]

Looking to utilise vref on a K60 Kinetis, which has VREFH and VREFL pins. Ideally referencing to 3v3, but very stable -ie not using the supply lines - what would be the best way of achieving this - a ...
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2answers
838 views

Why is the reason of using BJTs instead of diodes in Bandgap references?

I'm just asking what is the main reason to use BJT transistors as pn or np junctions for bandgap voltage reference instead of using just pn or np diodes also available on CMOS technologies.
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552 views

How do you generate a reference voltage in a circuit?

Hi Im very new to electronics and had a pretty basic question about voltage reference. So Ive finally understood that in order to check a voltage in most circuits, a voltage reference is used. The ...