Power demand in portable designs CAN require in some specific application more than 1 A. A method consists in paralleling two DC to DC converters on the same load instead of placing a single higher current converter with lower switching frequency. This solution may be space saving, cost effective and thermally beneficial. However, DC to DC convert
ers regulate their own output voltage with a tolerance which includes bandgap deviation, Comparator offsets and closed loop regulation parameters. Using converters with external resistor bridge implies to also take into consideration resistor accuracies. This application note will detail the tips and tricks to implement load sharing method with NCP1532. The NCP1532 dual step down DCDC converter includes two channels externally adjustable from 0. 9 V to 3. 3 V which CAN source totally up to 1. 6 A, 1. 0 A maximum per channel. The MODE/SYNC pin allows to force the part in PWM mode which is required to operate with the load sharing method. Both converter CAN operate out of phase at 2. 25 MHz or CAN be synchronized in phase to an external Clock External Components Must Be Evaluated Paralleling two DC to DC converters to increase output current capability requires additional ballast resistors to prevent the fact that the two converters are not exactly set at the same voltage. Using the NCP1532 we CAN consider that the deviation coming from the error Amplifier and reference voltage CAN be negligee inside the same circuit. Handled designers must minimize these ballast resistors to reduce power looses and ensure acceptable load regulation performance.