ST1S09 description

AN2603

4/23

Doc ID 13778 Rev 3

1

ST1S09 description

The ST1S09 is a family of adjustable current mode PWM synchronous step-down DC-DC

converters with internal 2 A power switch. It is a complete 2 A switching regulator with

internal compensation which eliminates the need for additional components. The ST1S09

devices operate at a fixed frequency of 1.5 MHz (typ).

To maintain good efficiency, the device operates in power-save mode at light load condition

(Figure 2 and Figure 3). When the load increases it automatically switches to PWM (pulse

width modulation) mode, in order to reduce the output voltage ripple (Figure 4 and Figure 5).

Figure 2.

Inductor current at light load