Hi, some time we are in need of multiple voltages for either ref voltage or for comparison or as simple voltage regulator with rotatory switch.
In this post we will explain how we can get these multiple voltages from the series of resistors. Generally, first choice come in to mind is voltage divider, but for 2-3 it is good choice but if it multiple in number, it not recommend to use the voltage divider.
for understanding we took one example as
lets say we required voltage values of vout = 4V, 3.5V, 3V, 2.5V, 2V, 1.9V, 1.8V, 1.7V, 1.6V, 1.5V, and 0.85V from vin = 4.95v
with the help of steps we try to solve this
step1.
fix the current flowing thro the series resistor as a starting point
lets say i = 1mA
step2.
so total resistor Rt = vin / i = 4.95 / 1mA = 4950 ohms
step3.
calculate the all resistance from following approach
for 4v = 4 / 1mA = 4000 ohms
for 3.5v = 3.5 / 1mA = 3500 ohms
for 3v = 3 / 1mA = 3000 ohms
for 2.5v = 2.5/ 1mA = 2500 ohms
for 1.9V, 1.8V, 1.7V, 1.6V, 1.5V, and 0.85 = 1900, 1800, 1700, 1600, 1500, 850 ohms respective
so the series of resistors arrange as
4950 – 4000 = 950 1st resistor
4000-3500 = 500 2nd resistor
like wise, diagram shown the complete values with output voltages.
while using these voltages, better use the buffer circuit before it.
hope you got it, comments are welcome.