The TPS54900 four-channel step-down converter uses voltage mode PWM control to provide four independently programmable output voltages. Each regulated channel includes a high-side PMOSFET switch with a typical rDS(ON) of 0.8 , which makes it suitable for high efficiency, low current applications. Commands sent to the TPS54900 over the four-wire serial port programs the outputs independently or globally to supply voltages from 7.5 V to 13.1 V in 0.4-V increments. When the input voltage is desired at an output, a bypass mode can be activated which fully enhances the PMOSFET switch and disables the switching circuitry of the selected channel. The TPS54900 is an ideal companion device to power THS7102 ADSL line drivers as a part of the AC5 central office ADSL chipset. With the AC5 chipset controlling the TPS54900 output voltages, significant power savings are realized by reducing the excess supply headroom on a per line basis.