A transformer driver enables a “non-power supply” engineer to quickly design a simple, unregulated, isolated DC/DC power supply. In the example shown, the required external components on the primary side are two decoupling capacitors for the input supply, and a resistor. For the secondary side, a transformer, where the winding ratios determine the isolated voltage level, a couple of diodes and a smoothing capacitor complete the isolated DC/DC power supply. This power supply architecture has no feedback loop, eliminating the need for an error amplifier and optocoupler or the complication of design loop compensation to address the tradeoffs between good transient response or high switching frequency capability and stability. The transformer driver has a built in primary side controller and a driving circuit to provide current to the primary windings of an external transformer. No external PWM controller is required. It also has a fixed duty cycle of 50% to prevent DC current flow in the transformer and cross conductance.