This document describes the operation of a buck converter circuit. It contains diagrams and simulations showing: 1) The buck converter circuit design with key components labeled including an input voltage of 12V, output voltage of 3.3V at 6.6A. 2) Simulations of the output voltage and current over time as the circuit operates, reaching the target output. 3) Simulations of the voltage, current, and power characteristics of the synchronous buck diode during initial turn-on, overshoot, and steady-state periods. 4) Simulations of the voltage, current, and power characteristics of the MOSFET during initial turn-on, overshoot, and steady-state periods.

1. Buck Converter
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V1
12Vdc
R8
1m
L3
10nH
1
2
R3
10
R7
0.5
0
R6
1m
Vo
R5
10k
L1
0.01uH
1 2
U2
40CPQ050
S
V2
Implementation = V_sig
U1
2SK3682
R4
22
C3
1000u
C2
2n
R1
10
C1
2n
R2
1m
L2
100uH
1 2
Vin = 12[V]
Vout = 3.3[V]
Iout=6.6[A]

2. Vout and Iout
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Time
0s 1ms 2ms 3ms 4ms 5ms 6ms 7ms 8ms 9ms 10ms
-I(R7)
0A
2A
3A
4A
5A
6A
7A
8A
9A
10A
SEL>>
V(VO)
0V
0.5V
1.0V
1.5V
2.0V
2.5V
3.0V
3.5V
4.0V
4.5V
5.0V
Iout=6.587[A]
Vout=3.294[V]

3. SBD Characteristic reference Output Voltage
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Time
0s 1ms 2ms 3ms 4ms 5ms 6ms 7ms 8ms 9ms 10ms
V(L2:1,U2:PIN1)*I(U2:PIN1)
-20W
-10W
0W
10W
20W
V(L2:1,U2:PIN1)
-4V
4V
8V
12V
16V
20V
SEL>>
I(U2:PIN1)
-5A
0A
5A
10A
15A
V(VO)
0V
1.0V
2.0V
3.0V
4.0V
5.0V
Overshoot
2
Initial State
1
Steady State
3
Vout
Current
Voltage
Power

4. Initial State SBD: Voltage, Current and Power
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1
Time
0s 10us 20us 30us 40us 50us 60us 70us 80us 90us 100us
V(L2:1,U2:PIN1)*I(U2:PIN1)
-20W
-10W
0W
10W
20W
V(L2:1,U2:PIN1)
-4V
0V
4V
8V
12V
16V
20V
I(U2:PIN1)
-5A
0A
5A
10A
15A
SEL>>

5. Overshoot SBD: Voltage, Current and Power
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2
Time
500us 510us 520us 530us 540us 550us 560us 570us 580us 590us 600us
V(L2:1,U2:PIN1)*I(U2:PIN1)
-20W
-10W
0W
10W
20W
SEL>>
V(L2:1,U2:PIN1)
-4V
0V
4V
8V
12V
16V
20V
I(U2:PIN1)
-5A
0A
5A
10A
15A

6. Steady State SBD: Voltage, Current and Power
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3
Time
5.00ms 5.01ms 5.02ms 5.03ms 5.04ms 5.05ms 5.06ms 5.07ms 5.08ms 5.09ms 5.10ms
V(L2:1,U2:PIN1)*I(U2:PIN1)
-20W
-10W
0W
10W
20W
SEL>>
V(L2:1,U2:PIN1)
-4V
0V
4V
8V
12V
16V
20V
I(U2:PIN1)
-5A
0A
5A
10A
15A

7. MOSFET Characteristic reference Output Voltage
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Time
0s 1ms 2ms 3ms 4ms 5ms 6ms 7ms 8ms 9ms 10ms
I(U1:2)*V(R1:1,U1:3)
-40W
120W
200W
SEL>>
V(U1:1,L2:1)
-4V
4V
12V
20V
V(R1:1,U1:3)
0V
10V
20V
30V
40V
I(U1:2)
-4A
0A
4A
8A
12A
16A
V(VO)
0V
1.0V
2.0V
3.0V
4.0V
5.0V
1 Initial State
2 Overshoot
3 Steady State
Vout
IDS
VDS
VGS
POWER

8. Initial State MOSFET: Turn On
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1
Time
0s 10us 20us 30us 40us 50us 60us 70us 80us 90us 100us
I(U1:2)*V(R1:1,U1:3)
-40W
40W
80W
120W
160W
200W
SEL>>
V(U1:1,L2:1)
-4V
0V
4V
8V
12V
16V
20V
V(R1:1,U1:3)
0V
10V
20V
30V
40V
I(U1:2)
-4A
0A
4A
8A
12A
16A

9. Overshoot MOSFET: Turn On
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2
Time
500us 510us 520us 530us 540us 550us 560us 570us 580us 590us 600us
I(U1:2)*V(R1:1,U1:3)
-40W
40W
80W
120W
160W
200W
SEL>>
V(U1:1,L2:1)
-4V
0V
4V
8V
12V
16V
20V
V(R1:1,U1:3)
0V
10V
20V
30V
40V
I(U1:2)
-4A
0A
4A
8A
12A
16A

10. Steady State MOSFET: Turn On
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3
Time
5.00ms 5.01ms 5.02ms 5.03ms 5.04ms 5.05ms 5.06ms 5.07ms 5.08ms 5.09ms 5.10ms
I(U1:2)*V(R1:1,U1:3)
-40W
40W
80W
120W
160W
200W
SEL>>
V(U1:1,L2:1)
-4V
0V
4V
8V
12V
16V
20V
V(R1:1,U1:3)
0V
10V
20V
30V
40V
I(U1:2)
-4A
0A
4A
8A
12A
16A