Fast Load Transient Regulation of Low-Voltage Converters with the Low-Voltage Transient Processor

The transient response of dc–dc converters with large conversion ratios is limited by the asymmetry of the current slew rate through the magnetic elements; under appropriate control, such a converter may respond much faster to an increase in load current than a decrease, or vice versa. In this paper, a low-voltage, unloaded, bidirectional dc–dc converter with a very fast current slew rate, called the low-voltage transient processor (LVTP), is placed in shunt across the output of a conventional dc–dc converter (the “primary regulator”) to equalize the effective current slew rate (the combination of the LVTP and primary regulator) seen at the load, so that the transient response to a load increase is the same as the response to a load decrease. The LVTP operates at very low voltages, enabling the use of small magnetic components with low losses even at high-frequency operation, allowing the overall efficiency of the system to be high. To demonstrate the concept, a 3 MHz bidirectional buck LVTP prototype was implemented and placed at the output of a 12–1.2 V microprocessor voltage regulator (VR). The VR with LVTP matched the performance of VRD10.1 VR reference design with half (4.10 mF) of the output capacitance of the original design.