Voltage Divider
Voltage Divider
A voltage divider taps a fraction of the supply voltage using two resistors — the workhorse of sensor and reference circuits.
The output is V_o = V_in·R_2/(R_1 + R_2). where V_in is the input voltage and R_1, R_2 the upper and lower resistors.
Inputs
V_in := 9 V=9 V
R_1 := 4700 Ohm=4700 Ω
R_2 := 2200 Ohm=2200 Ω
The output is the supply scaled by the resistor ratio.
V_o := V_in·R_2/(R_1 + R_2)=2.87 V
Results
The output depends only on the ratio of the resistors, not their absolute values. Loading the output with a low resistance will pull this voltage down.
Assumptions & limitations
- No load current drawn from the tap.
- Ideal resistors.
- Steady DC.