6 Linear Regulator with Adjustable Soft-Start and High Output Voltage Accuracy

For low current rails, a linear regulator with a user-programmable soft-start minimizes stress on the input power source by reducing the capacitive inrush current on start-up, especially from highly capacitive loads or with processors requiring many bypass capacitors. The TPS748A adjustable linear regulator provides a monotonic (non-negative slope), linear soft-start ramp that is well-suited for powering many different types of processors. The linear regulator also includes enable and power good pins to aid in sequencing schemes. Figure 6-1 illustrates the start-up waveform showing the start-up times varying over several soft start capacitor values.

Figure 6-1 TPS748A Start-up Waveform

The linear regulator has a precision reference and error amplifier delivering 0.85% accuracy over load, line, temperature, and process variations. The reference voltage accuracy rivals many switch-mode DC/DC converters on the market, allowing a linear regulator to be used in lower current applications without sacrificing feature and sequencing requirements or output voltage accuracy performance.