The TPS6126x is based on a quasi-fixed frequency, pulse-width-modulation (PWM) controller using synchronous rectification to obtain maximum efficiency. At low load currents, the converter enters Power Save Mode to ensure high efficiency over a wide load current range. The TPS6126x is based on a current mode topology. The inductor current is regulated by a fast current regulator loop which is controlled by either a voltage control loop or a reference current. The controller also uses input and output voltage feedforward. Changes of the input and output voltages are monitored and immediately change the duty cycle in the modulator to achieve a fast response to those errors. In addition, the average output current can be programmed as well. An external resistor is used to program the average output current.