DC-DC Converter
The DC-DC converter part models a step-down (buck) switching converter module. It converts a higher input voltage to a regulated lower output, defaulting to 5 V at up to 2 A with 85% efficiency. It is a behavioural 2-port model: the output side is regulated at the setpoint, and the input draws whatever current is needed to deliver the output power.
Pinout
| Pin | Label | Description |
|---|---|---|
| in_pos | IN+ | Input supply positive |
| in_neg | IN− | Input supply negative (GND) |
| out_pos | OUT+ | Regulated output positive |
| out_neg | OUT− | Output negative (GND) |
Specifications
| Parameter | Value |
|---|---|
| Input range (Vin) | 7–35 V (12 V nominal) |
| Output (vout) | 5 V default, adjustable |
| Current limit (iLimit) | 2 A default |
| Efficiency (eta) | 0.85 (85%) |
vout, iLimit, and eta can be overridden via the Inspector properties panel. eta must be in the range (0, 1], and both iLimit and vout must be greater than 0.
Regulated output and current limit
The converter holds OUT+ at the vout setpoint as long as the load stays within the current limit (constant-voltage mode). If the load tries to draw more than iLimit, the converter switches to constant-current mode: it caps output current at iLimit and the output voltage sags below vout. This mirrors how a real module behaves when its current limit kicks in.
Efficiency and input current
The model conserves power. The input draws:
Iin = Pout / (eta × Vin)where Pout is the power delivered to the load. Because efficiency is below 100%, the input always draws more power than the output delivers — the difference (about 15% at the default eta) is lost as heat, which is why a switching converter runs cooler than a linear regulator across a large voltage drop.
A step-down (buck) converter trades voltage for current: because it outputs a lower voltage, its input current is always less than its output current. For example, drawing 1 A at 5 V (5 W) from a 12 V input pulls roughly 5 / (0.85 × 12) ≈ 0.49 A on the input — about half the 1 A output, and a touch above the lossless 5 W / 12 V ≈ 0.42 A because of the 85% efficiency loss. (A step-up/boost converter does the opposite: it outputs a higher voltage, so its input current exceeds its output current.)
This is a steady-state efficiency model. It does not simulate switching ripple.
Example circuit
12 V supply + ─── IN+ OUT+ ─── 5 V rail (Arduino VIN / logic)
12 V supply − ─── IN− OUT− ─── GNDConnect IN+ and IN− to the input supply, OUT+ and OUT− to the output load. Adjust vout in the Inspector to change the regulated output setpoint — for example, set it to 3.3 V to feed a 3.3 V logic rail from the same 12 V input.