Question

In the circuit with ideal devices, the power MOSFET is operated with a duty cycle of 0.4 in a switching cycle with \( I = 10 \, \text{A} \) and \( V = 15 \, \text{V} \). The power delivered by the current source, in W, is:

\[ \text{(round off to the nearest integer).} \]

Hint:

For switching circuits with ideal devices, the average power delivered by a current source is given by: \[ P = I \cdot V_{{across source}} \cdot (1 - D) \] where \( D \) is the duty cycle and the source voltage appears during the OFF time.

Answer 1

This is a typical buck-boost or switched-mode circuit. The power source delivers current \( I = 10 \, \text{A} \) continuously, but voltage is only applied across the load during the off time of the MOSFET.

Given:
- Duty cycle \( D = 0.4 \)
- So switch is OFF for \( 1 - D = 0.6 \) fraction of time
- During OFF time, the diode conducts and the voltage across the current source is \( V = 15 \, \text{V} \)

Average power delivered by the source:
\[ P = I \cdot V \cdot (1 - D) = 10 \cdot 15 \cdot 0.6 = 90 \, \text{W} \]