BQ25890_16 Datasheet, PDF (21/69 Pages) Texas Instruments – Adjustable Voltage USB On-the-Go Boost Mode

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bq25890, bq25892
SLUSC86B – MARCH 2015 – REVISED MAY 2016
Feature Description (continued)
9.2.3.3 Input Source Type Detection
After the VBUS_GD bit is set and REGN LDO is powered, the charger device runs Input Source Type Detection
when AUTO_DPDM_EN bit is set.
The bq25890 follows the USB Battery Charging Specification 1.2 (BC1.2) and to detect input source
(SDP/CDP/DCP) and non-standard adapter through USB D+/D- lines. In addition, when USB DCP is detected, it
initiates adjustable high voltage adapter handshake on D+/D-. The device supports MaxCharge™ handshake
when MAXC_EN or HVDCP_EN is set. The bq25892 sets input current limit through PSEL and OTG pins.
After input source type detection, an INT pulse is asserted to the host. In addition, the following registers and pin
are changed:
1. Input Current Limit (IINLIM) register is changed to set current limit
2. PG_STAT bit is set
3. PG pin goes low (bq25892)
The host can over-write IINLIM register to change the input current limit if needed. The charger input current is
always limited by the lower of IINLIM register or ILIM pin at all-time regardless of Input Current Optimizer (ICO) is
enable or disabled.
When AUTO_DPDM_EN is disabled, the Input Source Type Detection is bypassed. The Input Current Limit
(IINLIM) register, VBUS_STAT, and SPD_STAT bits are unchanged from previous values.
9.2.3.3.1 D+/D– Detection Sets Input Current Limit (bq25890)
The bq25890 contains a D+/D– based input source detection to set the input current limit automatically. The
D+/D- detection includes standard USB BC1.2, non-standard adapter, and adjustable high voltage adapter
detections. When input source is plugged-in, the device starts standard USB BC1.2 detections. The USB BC1.2
is capable to identify Standard Downstream Port (SDP), Charging Downstream Port (CDP), and Dedicated
Charging Port (DCP). When the Data Contact Detection (DCD) timer of 500ms is expired, the non-standard
adapter detection is applied to set the input current limit.
When DCP is detected, the device initates adjustable high voltage adapter handshake including MaxCharge™,
etc. The handshake connects combinations of voltage source(s) and/or current sink on D+/D- to signal input
source to raise output voltage from 5 V to 9 V / 12 V. The adjustable high voltage adapter handshake can be
disabled by clearing MAXC_EN and/or HVDCP_EN bits .
Non-Standard
Adapter
Non-Standard Adapter
(Divider 1: 2.1A)
(Divider 2: 2A)
(Divider 3: 1A)
(Divider 4: 2.4A)
Adapter Plug-in
or
EN_DPDM
USB BC1.2
Detection
Ajustable High Voltage Adapter
Handshake
SDP (USB500)
(500mA)
CDP
(1.5A)
0D[&KDUJHΠ$SDSWHU
(1.5A)
Figure 9. USB D+/D- Detection
DCP
(3.25A)
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