Fujitsu MB96300 series Hardware Manual page 768

CHAPTER 29 USB FUNCTION
29.4.3 Suspend Mode Function
A USB device must have bus power supply configuration with a power consumption
less than 500µA in SUSPEND mode. This section describes the USB device procedure
to enter SUSPEND mode and then STOP mode.
■ USB function SUSPEND mode
When the USB device core detects a SUSPEND mode request, the SUSP flag of the UDCS register is set.
The figure below shows an example of the suspend operation:
Host PC
Device
SUSP
STP
●
SUSPEND mode operation
The USB function detects a SUSPEND mode after 3 ms without activity on the USB bus. If so, the SUSP
flag in the UDCS register is set. If a USB device supports remote wake-up, the USB function waits for
another 2 ms (which blocks remote wake-up during this time period), and set the device to STOP mode.
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Figure 29.4-8 Suspend Operation
1ms 1ms 3ms
SOF SOF SOF
Suspend state
Remote wake-up support
2ms
SUSP flag
Soft clear