9.2.2 Typical Application with External Power Path

In the case where a system needs to be immediately powered up from VBUS when the battery is overdischarged

or dead, the application circuit shown in Figure 9-6 can be used to provide a power path from VBUS/PMID to

VSYS. PFET Q4 is an external PFET that turns on to supply VSYS from the battery when VBUS is removed;

PFET Q4 turns off when VBUS is plugged in and VSYS is supplied from VBUS/PMID.

2.2 …F

2.2 …F

REGN

47 nF

R

VSYS

10 µF

REGN

10 …F

VBUS

REGN

REGN

STAT

ICHG

GND

Q3

Q1

Q2

PMID

BAT

TS

PGND

BTST

SW

Q4

VBUS

VBUS

Figure 9-6. Typical Application Diagram with Power Path

9.2.2.1 Design Requirements

For design requirements, see Section 9.2.1.1.

BQ25302

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