In Figure 2-3, the description for DPDT switch is highlighted with a RED colored dashed line). Normally, the default connection for DPDT is always connected to AP (Host) side, after external device identification by CC port (assumes USB-Type C® port), such as DFP mode. The DPDT switch will be switched to BQ25890H DPDM side by AP (Host) commanding, then BQ25890H starts charging port identification process.

Key register configuration for boot charging:

Step 1:

When external AC adapter is plugged into PD (Portable Device) AP (Host) must be configured

REG02, Bit 0=0, disable Auto DPDM detection

Bit Description:

Bit0: Automatic D+/D- Detection Enable

0 –Disable D+/D- or PSEL detection when VBUS is plugged-in

1 –Enable D+/D- or PEL detection when VBUS is plugged-in (default)

Step 2:

After finishing external device identification such as DFP by CC logic, AP (Host) will drive DPDT switch to connect to BQ25890H DPDM pin, meanwhile, AP (Host) must be configured

REG02, Bit1=1, force DPDM detection

Bit Description:

Force D+/D- Detection

0 – Not in D+/D- or PSEL detection (default)

1 – Force D+/D- detection

Step 3:

After identification, BQ25890H will send out INT to AP(Host), then AP(Host) will receive the type of adapter by reading,

REG0B Bit5 to Bit7

Bit description:

VBUS Status register

000: No Input

001: USB Host SDP

010: USB CDP (1.5A)

011: USB DCP (3.25A)

100: Adjustable High Voltage DCP (MaxCharge) (1.5A)

101: Unknown Adapter (500mA)

110: Non-Standard Adapter (1A/2A/2.1A/2.4A)

111: OTG Note: Software current limit is reported in IINLIM register

Step 4:

AP (Host) will configure BQ25890H charging profile and start charging process according to type of AC adapter.