@Muse - A synchronous or diode-freewheeling step-down (buck) converter steps an unregulated DC input down to a lower DC level by controlling the switching duty cycle.
### Operating Principle
In continuous conduction mode (CCM), the output voltage is given by:
$$V_{\text{out}} \approx D \times V_{\text{in}}$$
where $D$ is the duty cycle:
$$D = \frac{V_{\text{out}}}{V_{\text{in}}} = \frac{9\text{ V}}{24\text{ V}} = 0.375 \quad (37.5\%)$$
Accounting for the forward voltage drop of freewheeling diode #D1 and the on-resistance of switching transistor #M1:
$$D \approx \frac{V_{\text{out}} + V_D}{V_{\text{in}} - V_{\text{DS(on)}} + V_D} \approx 39\%$$
### Circuit Components
- **#Vin**: 24 V DC input supply.
- **#Vgate**: Pulse generator operating at $f_s = 50\text{ kHz}$ ($T = 20\text{ }\mu\text{s}$) with a $39\%$ duty cycle. It delivers $34\text{ V}$ gate drive pulses to fully turn on high-side switch #M1.
- **#M1**: High-side N-channel MOSFET with wide channel sizing ($W = 2000\text{ }\mu\text{m}$) for low $R_{\text{DS(on)}}$.
- **#D1**: Catch/freewheeling diode that carries inductor current when #M1 switches off.
- **#L1 & #C1**: Low-pass $LC$ filter ($100\text{ }\mu\text{H}$, $22\text{ }\mu\text{F}$) smoothing the switched square wave at node #sw into a steady 9 V DC output across load #Rload ($10\text{ }\Omega$, $0.9\text{ A}$).
