# Calculators: Resistor Dividers

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Enter new numbers and see the remaining output value change. Floating point format ("1.1E-6") works; engineering units ("1.1u", etc.) do not.

Note that the voltages are simply ratios, as are the resistances, so their actual units do not matter (as long as they're the same). They're both labeled in their base units for convenience.

By the way, since these are linear equations, you can enter "nonsense" values, and still get "realistic" numbers out—to achieve Vo > Vi from a voltage divider would require negative resistance, which is exactly the solution you will find. It's your problem to find or make the negative resistor...

Note that an infinite value resistor is simply an open circuit.

## Single Divider (2 resistor)

All four permutations are easily calculated, and provided below. R1 = Ω, R2 = Ω, Vi = V, = Vo =   V R1 = Ω, R2 = Ω, Vo = V, = Vi =   V Vi = V, Vo = V, R1 = Ω = R2 =   Ω Vi = V, Vo = V, R2 = Ω = R1 =   Ω

## Double Divider (3 resistor, two output)

Solutions in all 15 permutations of this network would be obnoxious, so these are only the two most common. R1 = Ω, R2 = Ω, R3 = Ω, V1 = V V2 =   V,   V3 =   V V1 = V, V2 = V, V3 = V, R1 = Ω R2 =   Ω,   R3 =   Ω

## Biased Divider (3 resistor, two input)

This network is used to offset the voltage range of a signal (e.g., ADC input range), or reduce the voltage range of a source (e.g., constraining the output of a rail-to-rail amplifier to a band within the supplies), or level-shift a wide-voltage or high-voltage logic signal to a smaller swing (e.g., interfacing CD4000 CMOS with others, generating a fixed hysteresis band for using a comparator as a precision Schmidt trigger), etc. Solve for Resistors Input High Voltage VIH = V Input Low Voltage VIL = V Output High Voltage VOH = V Output Low Voltage VOL = V Bias/Supply Voltage VS = V Series Resistance R1 = Ω Pull-Up Resistance R2 = Ω Pull-Down Resistance R3 = Ω
 Solve for Output Voltages Series Resistance R1 = Ω Pull-Up Resistance R2 = Ω Pull-Down Resistance R3 = Ω Input High Voltage VIH = V Input Low Voltage VIL = V Bias/Supply Voltage VS = V Output High Voltage VOH = V Output Low Voltage VOL = V

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