In a Series Op-Amp Regulator, given R1=4.0kΩ, R2=10kΩ, R3=4.9kΩ, VZ=3.6V, VIN=14V.
Assume IL=260mA, determine the power dissipation by Q1.
To determine the power dissipation by Q1, we need to calculate the voltage across Q1 and the current flowing through it.
Step 1: Calculate the voltage across Q1.
The voltage across Q1 can be calculated using the formula for voltage division:
VQ1 = VIN * (R2 / (R1 + R2))
VQ1 = 14V * (10kΩ / (4.0kΩ + 10kΩ))
VQ1 = 14V * (10kΩ / 14.0kΩ)
VQ1 = 10V
Step 2: Calculate the current through Q1.
The current through Q1 can be calculated using Ohm's Law:
IQ1 = (VZ - VQ1) / R3
IQ1 = (3.6V - 10V) / 4.9kΩ
IQ1 = -6.4V / 4.9kΩ
IQ1 ≈ -1.306mA
Note: The negative sign indicates the direction of current flow.
Step 3: Calculate the power dissipation by Q1.
The power dissipation by Q1 can be calculated using the formula:
PQ1 = IQ1 * VQ1
PQ1 = -1.306mA * 10V
PQ1 ≈ -13.06mW
Since we have a negative power dissipation value, it indicates that Q1 is absorbing power instead of dissipating it.
Thus, the power dissipation by Q1 is approximately -13.06mW.