Transistor Switch Saturation Calculator

Calculate the base resistor needed to drive a BJT transistor into saturation for switching applications.

Inputs

Supply Voltage Vcc (V)

Load Current Ic (mA)

Input Voltage Vin (V)

GPIO/logic level driving the base

hFE (DC Current Gain)

From transistor datasheet

Saturation Factor

Overdrive factor (typically 2-10)

Results

Base Resistor (Rb)

—

Base Current (Ib)

—

Power in Rb

—

Vce(sat) drop

~0.2 V