TPS2549 Datasheet, PDF (26/42 Pages) Texas Instruments – USB Charging Port Controller and Power Switch With Cable Compensation

TPS2549
SLUSCP2 – SEPTEMBER 2016
www.ti.com
8.4.5.1 DCP BC1.2 and YD/T 1591-2009
Both standards specify that the D+ and D– data lines must be connected together with a maximum series
impedance of 200 Ω, as shown in Figure 44.
5V
200 Ω
(m a x.)
V_BUS
D–
D+
GND
Figure 44. DCP Supporting BC1.2 and YD/T 1591-2009
8.4.5.2 DCP Divider-Charging Scheme
The device supports divider3, as shown in Figure 45. In the Divider3 charging scheme the device applies 2.7 V
and 2.7 V to D+ and D– data lines.
V_BUS
5V
D–
2.7 V
2.7 V
D+
GND
Figure 45. Divider 3 Mode
8.4.5.3 DCP 1.2-V Charging Scheme
The DCP 1.2-V charging scheme is used by some hand-held devices to enable fast charging at 2 A. The
TPS2549 device supports this scheme in DCP-auto state before the device enters BC1.2 shorted mode. To
simulate this charging scheme, the D+ and D– lines are shorted and pulled up to 1.2 V for a fixed duration. Then
the device moves to DCP shorted mode as defined in the BC1.2 specification and as shown in Figure 46.
V_BUS
5V
200 Ω (m a x.) D–
1.2 V
D+
GND
Figure 46. 1.2-V Mode
8.4.6 DCP Auto Mode
As previously discussed, the TPS2549 device integrates an auto-detect state machine that supports all the DCP
charging schemes. The auto-detect state machine starts in the Divider3 scheme. However, if a BC1.2 or YD/T
1591-2009 compliant device is attached, the TPS2549 device responds by turning the power switch back on
without output discharge and operating in 1.2-V mode briefly before entering BC1.2 DCP mode. Then the auto-
detect state machine stays in that mode until the device releases the data line, in which case the auto-detect
state machine goes back to the Divider3 scheme. When a Divider3-compliant device is attached, the TPS2549
device stays in the Divider3 state.
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