6-A Synchronous Buck Converter with Minimal External Components (PMP2942)
The TPS40140 is a dual synchronous buck controller that can be used for a two-phase single output or for two independent outputs. The controller has an input voltage rating of 4.5 to 15V for the chip VCC and 2 to 40V for the power stage. It will work in many applications with 5, 12 and 24V inputs. The controller can also accept input voltages from two different sources. Current mode control uses the inductor DCR to minimize impacts on the efficiency. A current sense resistor could be used for improved accuracy. Additionally, the chip features a 700mV reference with better than 1% accuracy over temperature. This circuit uses the TPS40140 in the dual synchronous buck configuration. A buck is typically used when the output voltage is always lower than the input voltage. Key considerations for this design are low output noise and synchronized switching. The TPS40140 provides a CLK IO pin that can be connected between devices to create up to 16 phases that are optimally shifted. The converter in this case is 5V to 2.5V @ 2A and 3.3V to 1.2V @ 4A.