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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.

2 Resistor Divider 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.

3 Resistor Divider 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.

Biased Divider

Solve for Resistors Solve for Output Voltages
Input High Voltage VIH = V Series Resistance R1 = Ω
Input Low Voltage VIL = V Pull-Up Resistance R2 = Ω
Output High Voltage VOH = V Pull-Down Resistance R3 = Ω
Output Low Voltage VOL = V Input High Voltage VIH = V
Bias/Supply Voltage VS = V Input Low Voltage VIL = V
Series Resistance R1 = Ω Bias/Supply Voltage VS = V
Pull-Up Resistance R2 =
 
Ω
Output High Voltage VOH =
 
V
Pull-Down Resistance R3 =
 
Ω
Output Low Voltage VOL =
 
V

 

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