ProtoFlow Circuit Benchmark: Five Designs and Verification Results

ProtoFlow completed five selected Easy schematic-design tasks adapted from PCBSchemaGen: a CAN transceiver, 60 V sensing divider, NTC temperature sensor, 3.3 V LDO supply and precision voltage reference. All five passed final review, with zero errors and warnings in their original ERC reports. Additional checks verified connectivity, component ratings, calculations and simulated behavior.

Each task began in a blank project and produced an editable schematic, netlist, BOM and engineering report. Interactive follow-up checks included model and fixture corrections; the results below describe the final reviewed designs. Review checked required pin memberships in all five saved exports and compared calculations with saved simulation data. Tasks were adapted from PCBSchemaGen_v2 revision e07c545f4c01a8026480b1093ee503a926ce2be5.

The SN65HVD230DR interface uses a regulated 3.3 V supply, 100 nF bypass capacitor and 120 Ω endpoint termination across CANH/CANL. It assumes shared ground, 3.3 V MCU logic and a second termination elsewhere on the bus. Exported connectivity matched every required pin assignment.

The termination is specified at ±1% and 0.25 W; the bypass capacitor is ±10%, X7R and 50 V. At a conservative 3.6 V differential, the termination dissipates approximately 0.109 W at its low-tolerance resistance. The final functional model passed loopback, standby release and reception from an externally driven dominant bus. A 1 ms run contained 1,280 samples; at approximately 40.4 µs, CANH = 2.50666 V and CANL = 0.79334 V, giving 1.71332 V differential. Recessive samples had approximately equal line voltages.

A 180 kΩ / 10 kΩ divider scales 60 V to VSENSE. Both resistors are Viking ARG-series 0805 thin-film parts specified at ±0.1%. The adapted task required 3.10–3.30 V nominal output and a maximum of 3.30 V across initial resistor tolerances.

The nominal simulation reported 3.15789 V and 315.79 µA, matching calculation. All four initial-tolerance corners passed. The component review applied the manufacturer’s lower-of-maximum-voltage-or-√(P×R) working-voltage rule and calculated a conservative 3.170634 V maximum under the stated temperature-drift assumptions. Output, tolerance and resistor-stress checks passed.

The sensor uses a 47 kΩ ±0.1% pull-up, Murata NCP18XH103F03RB thermistor (10 kΩ at 25°C, ±1%) and 10 nF C0G capacitor from TEMP_ADC to ground, powered from 3.3 V with a high-impedance ADC input. Each temperature test used the corresponding resistance from Murata’s NCPxxXH103 table.

All three simulated operating points matched the calculations to the reported precision. At 25°C, current is 57.895 µA, estimated thermistor dissipation is 33.52 µW and calculated self-heating is approximately 0.034°C using the typical dissipation constant. The RC cutoff is 1.93018 kHz, with approximately 380 µs electrical settling to 99%. The filter response changes with thermistor resistance, as shown above.

The TLV1117-33IDCYR circuit converts 12 V to 3.3 V for a 0–25 mA external load and 0–50°C ambient. Pin 1 is ground, pin 2 and the tab are output, and pin 3 is input. A 560 Ω preload adds approximately 5.9 mA. Input/output capacitors are specified at 22 µF ±20%, rated 35 V and 10 V respectively; the output specification requires at least 10 µF effective capacitance and 0.2–0.5 Ω ESR over operating conditions.

Behavioral-model results

Load-step calculation

The model uses an instantaneous 30 mΩ output resistance and 0.3 Ω capacitor ESR. Initial small-signal impedance is 30 mΩ || 300 mΩ = 27.27 mΩ, predicting approximately 0.545 mV for a 20 mA step. The settled change is ΔV = ΔI × Rout = 20 mA × 30 mΩ = 0.600 mV, consistent with the saved result. The audit used 1 µs load edges and 60,020 samples; the reported 12.85 µs recovery is settling to within 10 µV of the new plateau.

Operating-point, input-sweep, startup and load-step checks passed their model targets. Calculated nominal pass-element loss is (12−3.3) × 25 mA = 0.2175 W, or 0.2688 W including preload, before additional bias losses.

The REF3033AIDBZR circuit derives nominal 3.3 V from 5 V with 100 nF input and 1 µF output decoupling, both specified as 25 V AVX X7R parts. Pin 1 is IN, pin 2 is OUT and pin 3 is GND; OUT connects directly to VREF. The intended source load is 0–1 mA.

Surrogate-model results

The simulations use REF3033_ESTIMATE_v1_NOT_TI with 3.3 V nominal output, a 130 µV/V line coefficient and 0.396 mΩ output resistance. The regulation sweeps reproduce those model coefficients: 130 µV/V × 1.7 V = 221 µV, and 0.396 mΩ × 25 mA = 9.9 µV. All selected numerical targets passed.

Datasheet-based error allocation

The separate accuracy budget uses the full box-method temperature excursion, with no series-filter voltage drop. Its 33.7425 mV total is a conditional engineering allocation across the listed test conditions. Schematic connectivity, decoupling and the original ERC review all passed.

Five selected tasks produced five accepted schematics with supporting connectivity checks, calculations and simulation records. The next step is to extend this evaluation to more complex circuits and physical hardware. No hardware was tested; active-device results shown here are functional or behavioral-model simulations, not measurements of actual chip performance.