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Voltage Unit Converter

Convert voltage between microvolts, millivolts, volts, kilovolts, and megavolts.

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Formula

1 V = 10³ mV = 10⁶ mu V

How It Works

This calculator converts between volts, millivolts, microvolts, and kilovolts for electronics engineers, instrumentation designers, and power systems professionals. Per SI Brochure (BIPM), the volt is defined as W/A = J/C = kg·m^2/(A·s^3), traceable to Josephson voltage standard with 10^-10 relative uncertainty. Electronics spans 12 orders of magnitude: nanovolts for SQUID magnetometers, microvolts for thermocouples (40 uV/C for Type K per IEC 60584), millivolts for Wheatstone bridges (2 mV/V typical), volts for logic levels (3.3 V LVCMOS per JEDEC), and kilovolts for ESD testing (8 kV per IEC 61000-4-2). Thermal noise in a 1 MHz bandwidth at 50 ohm: 0.91 uV RMS per Johnson-Nyquist equation.

Worked Example

Problem

A Type K thermocouple produces 4.096 mV at 100 C (cold junction at 0 C). Design signal conditioning to interface with a 12-bit ADC (0-3.3 V range).

Solution

Thermocouple output: 4.096 mV = 4096 uV = 0.004096 V
ADC LSB: 3.3 V / 4096 = 0.8057 mV = 805.7 uV
Required gain: 3.3 V / 4.096 mV = 806x (for full-scale at 100 C)
Practical gain: 800x using two stages (20x × 40x) per instrumentation amplifier
Output at 100 C: 4.096 mV × 800 = 3.277 V (within 0-3.3 V range)
Temperature resolution: 0.8057 mV / 800 / 40 uV/C = 0.025 C per LSB

Practical Tips

✓Thermal noise voltage per Johnson-Nyquist: V_n = sqrt(4kTRB) where k = 1.380649 × 10^-23 J/K. At 290 K, 50 ohm, 1 MHz: V_n = 0.91 uV RMS. This sets fundamental SNR limit for sensitive measurements
✓Logic voltage levels per JEDEC: LVTTL Vih > 2.0 V, Vol < 0.4 V; LVCMOS 3.3 V Vih > 2.0 V, Vol < 0.4 V; LVCMOS 1.8 V Vih > 1.17 V, Vol < 0.45 V. Verify both high and low thresholds for reliable interfacing
✓ESD test levels per IEC 61000-4-2: contact discharge 2-8 kV, air discharge 2-15 kV. A 2 kV ESD pulse contains ~0.5 mJ but delivers 7.5 A peak current - enough to damage 3.3 V CMOS gates

Common Mistakes

✗Confusing mV (10^-3 V) with uV (10^-6 V) - they differ by 1000x. Thermocouple output is mV-range; amplifier input noise is uV-range. A 10 uV noise on 4 mV signal = 0.25% error
✗Ignoring voltage drop in high-current paths - per IPC-2221, a 10 A current through 10 mohm trace resistance causes 100 mV drop, significant for 3.3 V logic rails (3% drop)
✗Using oscilloscope with wrong vertical scale - mixing up mV/div and V/div leads to 1000x amplitude error. A 5 mV signal on 5 V/div scale appears as flat line

Frequently Asked Questions

What is a typical noise floor in microvolts?

Thermal (Johnson) noise at 290 K: V_n = 0.13 × sqrt(R × BW_MHz) uV. For 50 ohm, 1 MHz: 0.91 uV RMS. Op-amp input noise: 1-20 nV/sqrt(Hz) typical, so 3 uV RMS in 100 kHz bandwidth. Low-noise instrumentation amplifiers (AD8429): 1 nV/sqrt(Hz) = 0.3 uV in 100 kHz BW.

When do I use millivolts vs volts on a multimeter?

Use mV range for: thermocouple output (0-50 mV), shunt resistor voltage (10-100 mV at rated current), bridge sensor output (0-30 mV), small voltage drops. Use V range for: power supply rails, logic signals, battery voltages. DMM resolution: 4.5-digit on mV range = 1 uV, on V range = 1 mV.

What is the difference between RMS and peak voltage?

For sine wave: V_peak = V_RMS × sqrt(2) = 1.414 × V_RMS per IEEE definition. Mains 230 V RMS = 325 V peak. For power calculations: P = V_RMS^2/R (true for any waveform). Multimeters display true RMS for AC; cheap meters assume sine wave and can have 40% error on non-sinusoidal waveforms.

Why are ESD test voltages specified in kV?

Human body model (HBM) per JEDEC JESD22-A114: 2-8 kV discharge through 1.5 kohm, 100 pF. Despite high voltage, energy is low (~0.2-3.2 uJ). Damage occurs from current density: 8 kV HBM produces 5.3 A peak current. Gate oxide breakdown in 3.3 V CMOS occurs at ~7 V, so 8 kV easily punches through multiple oxide layers.

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