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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615 views

CAN Reference Output Voltage

I'm designing a CAN-based platform using the Microchip MCP2551 transmitter. The circuit looks like that: Notice the unconnected pin VREF. I tested the circuit on a prototype and CAN is working. What ...
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328 views

How improve temperature sensitivity of HP 721A DC Power Supply voltage reference?

I have a sentimental affection for my HP 721A DC Power Supply: http://hpmemoryproject.org/pict/wall_a/anim/721a_q90/viewer.htm Rugged, dependable, and roughly as old as I am, it is also pretty ...
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315 views

Preparing Signal for Sampling

I want to sample a voltage signal from mains. I found the following circuit but im not sure how it works. The circuit consists of precision amplifier and a buffer which I can't make sense of, the rest ...
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706 views

Detect power supply voltage threshold, while consuming very low current

Lead acid batteries get damaged by over-discharge somewhat like lithium polymer batteries. I need a circuit that will cut off the load from the battery when it drops below about 10v. That is the easy ...
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110 views

Internal reference of MCU

The internal reference of the MCU is 1.45 V. I am relying on this to measure ambient temperature ratio-metrically using NTC and a resistor. The MCU datasheet says that the internal voltage reference ...
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1answer
180 views

AdvRef pin setup

I have an MCU Cortex M4 that don't have any internal voltage reference but only external. I need to setup a reference on ADVREF pin. I found different schematics used: Ex. 1: Ex. 2: Ex. 3: ...
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1answer
67 views

Zener voltage resolution at fixed current and load?

Under a fixed optimum current and negligible load (ie being used as a reference into an opamp) how steady is the voltage of a smoothed zener? The scenario is a zener carrying a current of 5mA in its ...
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818 views

The role of reference voltage in buck converters?

I asked a question here which made it quite clear that it's probably not a good start to make something that I plug directly into the mains. Instead, I've decided to build a low-voltage buck ...
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1k views

Design Decisions for using ADC with no VREF

I was looking at Freescale's KE02 processor family, and the MCU designers made an interesting design decision revolving around the ADC that I can't completely wrap my head around. The KE02 has an ...
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857 views

3v3 Microcontroller controlling a MOSFET that needs 5V

I'm designing a heater controller that has a primary input voltage between 12 and 24V. Everything except the heater runs on 3V3, including microcontroller, LED's, potentiometers and the MOSFET. The ...
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110 views

Use reference voltage as power suppy

I am using MCP3202 which does not have Vref as independent input. The datasheet states that the current consumption is: 550 μA max. active current at 5V Can I ...
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3answers
2k views

Measuring a voltage that is higher than your reference voltage

Question: How to measure an input power rail? Let's say I want to build a circuit that switches in a load that draws 1A from a 5V power rail (that is the supply for the device) and then measures that ...
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1answer
808 views

Inaccurate BandGap measurement

I've followed advice on the web on how to use "bandgap" voltage reference to measure supply voltage, however, the measurements are not as accurate as the ADC can be on an Arduino Mega. On the one ...
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4k views

Why do they make traces to LTZ1000 in spiral shape?

I was browsing Google images of LTZ1000 voltage reference IC. I saw that in some of the PCBs, the traces that go to LTZ1000 are in spiral shape and cut out gaps are left between them. What is the ...
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1answer
78 views

connecting 2 GNDs with relative voltage difference

I have USB ground and Lab Voltage Source ground, for which I need common reference. I thought I could just connect them together, but I found, that USB ground is relatively higher than Voltage Source ...
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1answer
111 views

Is it ok to use voltage dividers instead of voltage regulators when adjusting reference voltages for opAmps?

My question is about manually adjustable circuits with a knob, coarse ect. When adjusting reference voltage of an opamp, for instance, trigger level of a schmitt trigger or gain of an amplifier ...
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1answer
201 views

Can you use a the vout of a regulator as the cathode and your full voltage as anode?

I have a servo from an rc car with 6 wires, it turns out the servo controller is built into the RC Car with a bad board. I have a motor, a gear box and a 10k pot attached to it. I'm trying to build a ...
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2answers
1k views

EMG design help using AD8221 INAMP

I'm designing active electrodes for surface EMG, active electrodes being electrodes directly connected to a pre-amp and filtering stage on the measurement site. Im working with the AD8221 IN-AMP to ...
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1answer
167 views

How to use and bias LM285 shunt voltage ref for virtual ground?

I'm adding a lab to my course, unfortunately at the last minute. I'm going to have them work on a single-sided biopotential amp, working off a 5V supply. I guessed at parts I'd need, and got LM285 2....
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3k views

How to create precision reference 2.5 voltage

Can I create a precision reference voltage of 2.5V using 7805 regulator and ordinary resistors(10% error)/diodes or do I need to rely on specific reference voltage generator?
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685 views

Can I adjust the volume of a DAC using PWM?

Here is a circuit that allegedly converts PWM into a precision voltage reference: (source: dangerousprototypes.com) I am thinking about feeding that reference into the reference line on this ...
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1answer
813 views

Modifying LM334 reference schematic to 100uA/500mV

I'm trying to understand how to modify the circuit below to provide a 100uA constant current drain and 500mV Vds for an ISFET. Based on the help so far, this is the schematic I've come up with:
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1answer
417 views

High precision frequency to voltage converter

Lets say I have some 10MHz (+-0.001HZ) precision reference signal that I want to convert to quite a precise 10V Voltage reference. Unfortunately I don't have anything like a josephson junction ...
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1answer
3k views

What do you need 1.018V for?

The Fluke 732A has among 10V and 1V references also a 1.018V reference (whereas the 10V is the "main" references and the others are formed by resistive voltage dividers). While having multiple ...
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2answers
5k views

using the Arduino internal reference 1.1v

So i want to measure a resistor of around 20 ohm in a voltage divider with an Arduino UNO R3. Is there any way on an arduino to use 1.1v instead of 5v? I want to do this to decrease the current, ...
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4answers
3k views

TLV431 precision voltage reference [duplicate]

I have used this circuit from the TLV431 datasheet and replaced the values according to what I need which is 2.48V. This output will be directed to an op-amp as a reference. My problem is I can't ...
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2answers
357 views

Precision Shunt Regulator Increasing Voltage overtime

I want to have a stable voltage of 2.47V using TLV431AC which is a precision voltage-adjustable shunt regulator. http://www.ti.com/lit/ds/symlink/tlv431b.pdf I am able to get it by putting a 5k ...
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1answer
435 views

MCP6N11 voltage reference and output problem

I am currently trying to setup an instrumentation amplifier and I used MCP6N11. Basically I'm just trying to test the instruamp to output a certain voltage gain before I connect it to my actual ...
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2answers
5k views

Long term effect of over-voltage on clamping diodes and ADC reference voltage

I am contemplating building a small voltage/current monitoring circuit that needs to monitor a wide range of voltages and currents. Currents will just be a single low-side shunt. Monitoring will be ...
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2answers
1k views

Set ground reference of a 5v DC power supply to the middle of a 24v DC power supply

I have 2 isolated AC/DC power supplies. one generates a regulated 5 volt power supply and other generates a 24 volt power supply as you can see in the picture below: I also have designed a circuit (...
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1answer
469 views

High Peak Current Voltage Regulator

I have an ICs which has an operating voltage range from 3.35V up to 4.5V. It typically needs a 20-milliamps current but it can have 1.9-amps current peak. Moreover, my system will work with a battery ...
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3answers
7k views

Why is there a 0R resistor linking GND and AGND in analog voltage reference circuit?

This is related to another question I've just posted (What's the purpose of a ferrite bead inductor on this circuit?), regarding the battery charger described in the AVR450 Application Note - ...
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2answers
9k views

What's the purpose of a ferrite bead inductor on this circuit?

I'm studying the analog voltage reference circuit described in the AVR450 Application Note - Battery Charger for SLA, NiCd, NiMH and Li-Ion Batteries, which schematic is below (copied from page 38). ...
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2answers
552 views

Which resistor watt rating to use for this circuit and Arduino 5V?

http://www.skillbank.co.uk/arduino/measure.htm I am looking to build the circuit this guy recommends for making a better analog reference source. I found the voltage reference diode, and now I am ...
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2answers
280 views

Known voltage/current source

I am working on an EVM for an electricity meter. Its manual says the EVM requires a known voltage and current source for the calibration. I bought a power supply and measure the output of the PSU by ...
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1answer
895 views

How to connect the power for VREFSD pin and anlog pin in STM32F3273 (ARM Cortex-M4) for SDADC application?

I have an analog amplifier which is powered at single-supply power and have an analog ground of 1.25V. I want to perform sdadc for my analog output. I am using STM32F373 (48pins), which is an ARM ...
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137 views

What should I use for a 3.3 voltage reference that sinks maximum of 1mA?

I am in search for stable and precise 3.3 voltage reference IC. I am using it for the temperature sensor application which only sinks 1mA at max. Can someone suggest me a best component/IC for this ...
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1answer
275 views

TLV431 as direct replacement of zener?

The answer here suggests using strings of suitable zener diodes to drop the cell-voltages of a battery stack down, to measure the individual voltages by standard (that is non-high voltage) ADCs. The ...
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1answer
672 views

Buffering Input Signal - Op Amp Alternatives

I need to buffer a 0-5V signal that is coming from a resistor network and being fed into an IC. When I feed it directly to the IC there is a loading effect and the value is changed specifically at 0V ...
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1answer
437 views

Voltage source for Vref or Voffset

I have a DiffAmp AD8132 following an OpAmp LT1818. A 1.5V voltage source, such as voltage divider, voltage reference, or voltage regulator should be connected to the B input pin of the DiffAmp to ...
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3answers
978 views

Generating various reference voltages in a circuit

How does one go about accurately setting reference voltages at various points in a given circuit (e.g. various threshold voltages). Obviously we can have a potential divider from the main power supply ...
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3answers
4k views

Understanding a circuit for reading current passing through human bodies

I found on Instructables this circuit that is used to detect when two conductive pads are touched at the same time by a person (or, in that particular example, a chain of people). Used in conjunction ...
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3answers
361 views

Accurate -2V reference

I have an old Keithley 175A multimeter that has been suffering from a bit of drift lately. Internally it uses a 6.35V zener and a couple of resistors to create a -2V reference, but the zener is ...
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4k views

Using a Zener for reference voltage

I want to use a 9.1V Zener diode for a ref voltage into a op amp comparator so that when the battery voltage (11-12V DC) drops below 9.5V DC it will cut the supply to the circuit via a P-channel ...
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1answer
201 views

Backward measurement of AVcc against reference voltage connected to ADC input

what you think about ADC backward measuring supply voltage in microcontroller? It looks interesting for battery-powered devices. The idea is: Connect constant voltage (some voltage reference IC) to ...
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1answer
3k views

Beta Multiplier Reference: What is going on with the current output?

I have been working on a beta multiplier reference circuit using a 0.35um CMOS process. The circuit was previously designed and tested for a 0.7um process, but otherwise there have been no changes to ...
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2answers
180 views

DC transient behavior of precision rectifier circuit

I am working on a homework problem that I do not understand the solution to. From my understanding the inverting input of the opamp is at 0. So when the input is positive, the output swings ...
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2k views

Why is 4.096V so often used as a voltage reference?

I get that each mV is equivalent to a bit in a 12-bit ADC, but why is 4.096V used so often? I've heard of this being from a "bridge". What does this mean and what is the historical significance?
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96 views

NCP51460 alternatives

The NCP51460 20mA Precision Voltage Reference with it's wide input voltage range of up to 28V seems interesting for our current project, more-so considering the very competitive current price at ...
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1answer
4k views

JTAG adapter without VTREF

I am designing a USB JTAG adapter using FT2232D. Most JTAG reference designs use a level translator to drive JTAG pins with VREF. I understand VREF is used because different voltage levels at target ...