7.4.1 PWM Mode

The TLV61048 uses a quasi-constant frequency pulse width modulation (PWM) at moderate to heavy load currents. Based on the VIN/VOUT ratio, a circuit predicts the required off-time. At the beginning of the switching cycle, the integrated NMOS switching FET, shown in the functional block diagram, is turned on. The input voltage is applied across the inductor and the inductor current ramps up. In this phase, the output capacitor is discharged by the load current. When the inductor current hits the current threshold that is set by the error amplifier output, the PWM switch is turned off, and the external power diode is forward-biased. The inductor transfers its stored energy to replenish the output capacitor and supply the load. When the off-time is expired, the next switching cycle starts again. The error amplifier compares the FB pin voltage with an internal reference, and its output determines the duty cycle of the PWM switching.

The TLV61048 has a built-in compensation circuit that can accommodate a wide range of input and output voltages for stable operation.