Texas Instruments BQ2419X I²C Controlled 4.5A Single Cell USB / Adaptor Charger Evaluation Module BQ24195LEVM-193 BQ24195LEVM-193 Datenbogen
Produktcode
BQ24195LEVM-193
D+
D-
V
DP_SRC
V
LGC_HI
I
DP_SRC
CHG_DET
V
DAC_REF
I
DM_SINK
R
DM_DWN
SLUSB97 – OCTOBER 2012
Figure 15. USB D+/D- Detection
DCD (Data Contact Detection) uses a current source to detect when the D+/D– pins have made contact during
an attach event. The protocol for data contact detect is as follows:
•
an attach event. The protocol for data contact detect is as follows:
•
Detect VBUS present and REG08[2]=1 (power good)
•
Turn on D+ I
DP_SRC
and the D– pull-down resistor R
DM_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 I
DP_SRC
and disconnect R
DM_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:
•
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:
•
Turn on V
DP_SRC
on D+ and I
DM_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
D– is high
•
Turn off V
DP_SRC
and I
DM_SINK
shows the input current limit setting after D+/D– detection.
Table 2. bq24195L, bq24195 USB D+/D– Detection
D+/D– DETECTION
OTG
INPUT CURRENT LIMIT
REG08[7:6]
0.5 sec timer expired in DCD
—
100 mA
00
(D+/D- floating)
USB Host
LOW
100 mA
01
USB Host
HIGH
500 mA
01
Charging Port
—
1.5 A
10
HIZ State wth 100mA USB Host
In battery charging spec, the good battery threshold is the minimum charge level of a battery to power up the
portable device successfully. When the input source is 100mA USB host, and the battery is above bat-good
threshold (V
portable device successfully. When the input source is 100mA USB host, and the battery is above bat-good
threshold (V
BATGD
), the device follows battery charging spec and enters high impedance state (HIZ). In HIZ state,
the device is in the lowest quiescent state with REGN LDO and the bias circuits off. The charger device sets
REG00[7] to 1, and the VBUS current during HIZ state will be less than 30µA. The system is supplied by the
battery.
REG00[7] to 1, and the VBUS current during HIZ state will be less than 30µA. The system is supplied by the
battery.
Once the charger device enters HIZ state in host mode, it stays in HIZ until the host writes REG00[7]=0. When
the processor host wakes up, it is recommended to first check if the charger is in HIZ state.
the processor host wakes up, it is recommended to first check if the charger is in HIZ state.
Copyright © 2012, Texas Instruments Incorporated
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