bq24296
bq24297
SLUSBP6A –SEPTEMBER 2013–REVISED OCTOBER 2013
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Detect VBUS present and REG08[2]=1 (power good)
Turn on D+ IDP_SRC and the D– pull-down resistor RDM_DWN for 40ms
If the USB connector is properly attached, the D+ line goes from HIGH to LOW, wait up to 0.5 sec.
Turn off IDP_SRC and disconnect RDM_DWN
The primary detection is used to distinguish between USB host (Standard Down Stream Port, or SDP) and
different type of charging ports (Charging Down Stream Port, or CDP, and Dedicated Charging Port, or DCP).
The protocol for primary detection is as follows:
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Turn on VDP_SRC on D+ and IDM_SINK on D– for 40ms
If PD is attached to a USB host (SDP), the D– is low. If PD is attached to a charging port (CDP or DCP), the
D– is high
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Turn off VDP_SRC and IDM_SINK
Table 2 shows the input current limit setting after D+/D– detection.
Table 2. bq24297 USB D+/D– Detection
D+/D– DETECTION
OTG
INPUT CURRENT LIMIT
REG08[7:6]
0.5 sec timer expired in DCD
(D+/D- floating)
—
Proceed to Non-standard
adapter detection
00
USB Host
USB Host
LOW
HIGH
—
100 mA
500 mA
3 A
01
01
10
Charging Port
When DCD 0.5 sec timer expires, the non-standard adapter detection is used to distinguish three different divider
bias conditions on D+/D- pins. When non-standard adapter is detected, the input current limit (REG0[2:0]) is set
based on the table shown below and REG08[7:6] is set to 10 (Adapter port). If non-standard adapter is not
detected, REG08[7:6] is set to 00 (Unknown) and the input current limit is set in REG0[2:0] to 500mA by default.
Table 3. bq24297 Non-Standard Adapter Detection
Input
Current
Limit
Non-Standard
D+ Threshold
D- Threshold
Adapter
Divider 1
Vadpt1_lo < VD+ < Vadpt1_hi
For VBUS=5V, typical range 2.4V < VD+ < 3.1V
Vadpt1_lo > VD- or VD- < Vadpt1_hi
For VBUS=5V, typical range 2.4V > VD- or VD- > 3.1V
2A
2A
1A
Divider 2
Divider 3
Vadpt2_lo < VD+ < Vadpt2_hi
For VBUS=5V, typical range 0.85V < VD+ < 1.5V
NA
Vadpt3_lo < VD+ < Vadpt3_hi
Vadpt3_lo < VD- < Vadpt3_hi
For VBUS=5V, typical range 2.4V > VD+ or VD+
3.1V
>
For VBUS=5V, typical range 2.4V < VD- < 3.1V
PSEL/OTG Pins Set Input Current Limit
The bq24296 has PSEL instead of D+/D-. It directly takes the USB PHY device output to decide whether the
input is USB host or charging port.
Table 4. bq24296 Input Current Limit Detection
PSEL
HIGH
HIGH
LOW
OTG
LOW
HIGH
—
INPUT CURRENT LIMIT
REG08[7:6]
100 mA
500 mA
3A
01
01
10
24
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