<b>Keypad-Programmable Reference Voltage Generation for DC-DC Converters</b> <b>Using Arduino-PWM: Proteus Simulation and Filter Optimization</b>

This study presents the design and simulation of a microcontroller-based programmable reference voltage system for DC-DC converters using a Proteus simulation environment. The proposed system combines an Arduino UNO virtual model with a 4×4 keypad interface and 16×2 LCD display to generate precision reference voltages through PWM-to-analog conversion. The Proteus implementation features: (1) accurate modeling of Timer1 10-bit PWM generation at 31.25 kHz, (2) SPICE-based simulation of the two-stage RC low-pass filter (1kΩ/10μF → 1kΩ/100nF), and (3) interactive virtual instrumentation for performance validation. Simulation results demonstrate the system's capability to produce stable reference voltages from 0V to 5.00V with 4.88 mV resolution. Virtual oscilloscope measurements show the filtered PWM output achieves <1.5% voltage ripple (p-p) when loaded with a 10kΩ impedance, with settling times of 70 ms for 0V→5V transitions. The Proteus model verifies the effectiveness of the digital control algorithm, including keypad debouncing (modeled with 50ms delay blocks) and dynamic PWM updates without voltage discontinuities. Comparative analysis between ideal mathematical models and Proteus simulations reveals a less than 3% deviation in output voltage accuracy across the operating range. The virtual testing environment enabled the optimization of filter components, demonstrating that increasing the second-stage capacitor to 100nF reduces ripple by 32% while maintaining acceptable settling characteristics. System response to simulated load transients (20%-80% step changes) confirms reference voltage stability within ±1% of setpoint. This work validates the feasibility of the design through comprehensive virtual prototyping, providing a cost-effective simulation framework for developing programmable reference systems before hardware implementation. The Proteus model serves as a versatile testbed for evaluating different filter configurations and control algorithms in power electronics applications.