Disclosed is a memory array in which the lower of two supply voltages from two power supplies is dynamically selected for bitline pre-charge operations. In the memory array, a voltage comparator compares the first supply voltage on a first power supply rail to a second supply voltage on a second power supply rail and outputs a voltage difference signal. If the voltage difference signal has a first value indicating that the first supply voltage is equal to or less than the second supply voltage, than a control circuit ensures that the complementary bitlines connected to a memory cell are pre-charged to the first supply voltage. If the voltage difference signal has a second value indicating that the first supply voltage is greater than the second supply voltage, then the control circuit ensures that the complementary bitlines are pre-charged to the second supply voltage. Also disclosed is an associated method.