The following figures show the attach timing of the USB
accessories and the relationship between the INTB assertion
and the CHG_DET assertion. FSA9280A implements the
optional data contact detection (DCD) feature of the USB
Battery Charging specification. The DCD detection ensures
VBUS >4.0V
proper connection of the DP_CON and DM_CON before
starting the USB charging detection scheme. This feature
allows for shorter attach times by eliminating long wait times
to allow full contact of the DP_CON and DM_CON pins.
Charger FET Closed
INTB Asserted and
registers written
VBUS Voltage
XXXXFXLOXATXXXXXXXXXXXXXXXXXXXXXXXXXXXXXFXLOXAXT XXXXXXXXXXX
ID Resistance
VBUS_OUT
170ms
Switch State
Closed (CDP Only)
CHG_DET Pin
INTB Pin
DCD-20ms
CHG DETECTION 150ms
100ms
Figure 9. USB Dedicated Charging Port (DCP) or Charging Downstream Port (CDP) Attach Timing
VBUS >4.0V
Charger FET Closed
USB Switches Closed
VBUS_IN
XXXXFXLOXATXXXXXXXXXXXXXXXXXXXXXXXXXXXXXFXLOXAXT XXXXXXXXXXX
ID Resistance
VBUS_OUT
DCD Checking 20ms
Open
USB Switch State
Charger Detection Time 110ms
130ms
Closed
Figure 10. USB Standard Downstream Port Attach Timing
VBUS >4.0V
VBUS Voltage
XXXFLXOXATXXX
ID Resistance
VBUS_OUT
Open
Switch State
Charger FET Closed
Configured Switches Closed
ID Detection Time 200ms
CHG_DET Pin
INTB Pin
200ms
100ms
Figure 11. Car Kit Type 1 and 2 Attach Timing
© 2009 Fairchild Semiconductor Corporation
FSA9280A • Rev 1.1.0
11
www.fairchildsemi.com