APPLICATION NOTE 752Creating a Fast Load TransientAbstract: A simple circuit generates fast load transients for thorough testing of power supplies.Many of Maxim's devices show a typical operating characteristic (TOC) graph with a very fast load transient. Ourcustomers sometimes ask us how we create such fast changes in load. Although commercially available dynamicload boxes are capable of supplying transients, they do not provide the fast rise times and fall times necessaryfor an attractive-looking TOC.To obtain fast load transients, we combine a power MOSFET and a couple of resistors right on the PC board ofthe device under test (DUT). Choosing the components is relatively easy. If the output voltage is positive, an nchannelMOSFET works great. The MOSFET is connected with a resistor from the source to ground (see Figure1). The MOSFET's gate is terminated with a 51W resistor to impedance-match the signal generator's output.