# Single-Switch Non-Isolated Resonant DC-DC Converter for Single-Input Dual-Output Applications
## 3 Model and Experimental Prototype
### Experimental Results  
The experimental prototype developed (Figure 6) allows the performance of the converter to be verified under different test conditions and also in step-down and step-up operation modes. The block diagram of the laboratory experimental prototype converter is shown in Figure 13. It consists mainly of a SIDO ZVS-QR SEPIC-Cuk combination converter, a resonant controller and a gate-driver circuit. Figure 11: Output voltage variation with \(R_{Load_{1}}\) and \(R_{Load_{2}}\) of 10 \(\Omega\), \(V_{g}\) = 10 V, with a change in switching frequency from 200 kHz to 290 kHz at 0.075 s.  
Figure 12: Output voltage variation at switching frequency from 290 kHz, \(V_{g}\) = 10 V, with a change in \(R_{Load_{1}}\) and \(R_{Load_{2}}\) from 20 \(\Omega\) to 10 \(\Omega\) at 0.075 s.  
The control scheme is developed by a cost-effective commercial resonant-mode controller (UC3863). This controller is optimized for zero-voltage switching quasi-resonant converters. Mainly, it consists of an internal voltage-controlled oscillator (VCO) and an error amplifier. It is used in this application to regulate the output voltages to \(\pm\)12 V from an input voltage ranging from 10 V to 14 V. The UC3863 allows setting a minimum and maximum frequency between 10 kHz and 1 MHz. The controller is configured to generate a minimum of 380 kHz and a maximum of 540 kHz switching frequencies for ZVS operation in step-up and step-down modes. The control signal generated by the controller needs to be adapted to an adequate level for the switching transistor gate. The gate-driver circuit must provide sufficient output current to charge the gate capacity within the required time. In this sense, the UCC27423 commercial gate driver used ensures proper switching conditions. The results shown in Figures 14 and 15 correspond to two different situations: when \(V_{g}\) is 10 V and when \(V_{g}\) is 14 V, both step-up and step-down configurations, with two balanced loads of 600 mA, one at the positive output and the other at the negative output (\(R_{Load_{1}}\) and \(R_{Load_{2}}\), respectively). Some measurements were made with multimeters that, in the range of 0-1 kV DC, have a maximum resolution of 0.1 mV and an accuracy of 0.15%. The waveforms were acquired by an analog four-channel oscilloscope with an analog bandwidth of 1 GHz and an analog sample rate of 5 GS/s. For voltage measurements, a differential voltage probe was used; its bandwidth was 200 MHz, the input impedance was 5 M\(\Omega\) and the maximum common-mode voltage was \(\pm\)750 V. An AC/DC current measurement probe, which provides a bandwidth greater than 120 MHz with selectable 5 A and 30 A measurement ranges, was also used; it also provides low-current measurement capability and accuracy to current levels as low as 1 mA, and it measures current pulses up to 50 A.  
Figure 13: Block diagram of the developed prototype. In step-up mode, the input voltage is set to 10 V to obtain two dual outputs of \(\pm\)12 V. For this, a switching frequency of 390 kHz with an off-time of 848 ns is obtained with a load connected to the positive output and another equal load connected to the negative output (two monopolar loads). While in step-down mode, the input voltage is set to 14 V to obtain two dual outputs of \(\pm\)12 V; in this case, a switching frequency of 530 kHz with an off-time of 848 ns is obtained with a load connected to the positive output and another equal load connected to the negative output (two monopolar loads). The input voltage is set to 14 V to obtain two dual outputs of \(\pm\)12 V; in this case, a switching frequency of 530 kHz with an off-time of 848 ns is obtained with a load connected to the negative output (two monopolar loads). The input voltage is set to 14 V to obtain two dual outputs of \(\pm\)12 V; in this case, a switching frequency of 530 kHz with an off-time of 848 ns is obtained with a load connected to the negative output (two monopolar loads). an off-time of 645 ns is obtained.