April 2009

Doc ID 8422 Rev 2

1/13

AN1441

Application note

ST890: a high side switch

for PCMCIA and USB applications

Introduction

The ST890 is a low voltage, P-channel MOSFET power switch, intended for high side load

switching applications. Its main applications are PCMCIA slots, portable equipment and

access bus slots. The device is useful in all the applications that need a supply with short-

circuit protection and programmable current limitation, such as slots in which cards can be

connected and disconnected without turning off the power supply.

Figure 1.

ST890 internal block diagram

www.st.com