AN3050

Powering peripherals

Doc ID 16207 Rev 1

7/18

4

Powering peripherals

In many applications, it is desirable to power external peripherals attached to the system

connector. Proper voltage for these peripheral devices is usually generated by a DC/DC

converter supplied by the battery (see Figure 2). This converter is enabled by the controller

when power for the peripheral is requested. The output of the converter is connected to the

output of the OVP device.

In the internal structure of STBP120 MOSFET, a diode (called reverse diode or body diode)

between OUT and IN is present. This diode allows the convertor output voltage (decreased

by the diode forward voltage drop, ca. 0.6 V) to appear at the STBP120 input. If this voltage

is higher than the STBP120 undervoltage (UVLO) threshold, the MOSFET is turned on and

the voltage drop across the STBP120 is reduced to a very small value, given by the

Note:

For safety reasons, the charger IC used should NOT allow the reverse current (i.e. it should

NOT contain the body diode between its output and input) to prevent the battery pack

voltage from appearing on the system connector.