at43usb355 ATMEL Corporation, at43usb355 Datasheet - Page 99

• Manufacturer Part Number: at43usb355
• Description: At43usb355 Full-speed Usb Microcontroller With Embedded Hub, Adc And Pwm
• Manufacturer: ATMEL Corporation

Figure 27. Port Power Management
Suspend and
Resume
Global Resume
Remote Wakeup
2603G–USB–04/06
BUS_POWER
GND
2. Individual Power Switching – Two microcontroller GPIO pins, PWR2N and PWR3N,
3. Multiple Ganged Overcurrent Protection – Overcurrent sensing is grouped physi-
Figure 27 shows a simplified diagram of a power management circuit of an AT43USB355
based hub design with global overcurrent protection and ganged power switching.
The AT43USB355 enters suspend only when requested by the USB host through bus inactiv-
ity for at least 3 ms. The USB hardware would detect this request, sets the GLB_SUSP bit of
SPRSR, Suspend/Resume Register, and interrupts the microcontroller if the interrupt is
enabled. The microcontroller should shut down any peripheral activity and enter the Power
Down mode by setting the SE and SM bits of MCUCR and then executes the SLEEP instruc-
tion. The USB hardware shuts off the oscillator and PLL.
Global resume is signaled by a J to K state change on Port0. The USB hardware enables the
oscillator/PLL, propagates the RESUME signaling, and sets the RSM bit of the SPRSR, which
generates an interrupt. The microcontroller starts executing where it left off and services the
interrupt. As part of the ISR, the firmware clears the GLB_SUSP bit.
While the AT43USB355 is in global suspend, resume signaling is also possible through
remote wakeup if the remote wakeup feature is enabled. Remote wakeup is defined as a port
Only if all of the Power Control Bits of ports 2 and 3 are cleared should the firmware de-
assert the PWRN pin.
must be assigned for each USB port to control the external switch such as the
MIC2026-2. Each of the Power Control Bits controls one PWRxN.
cally into one or more gangs, but reported individually.
PWRN
IN
CTL
GND
SWITCH
AT43USB355
OVCN
FLG
OUT
VCC
PORT2_POWER
PORT3_POWER
PORT2_GND
PORT3_GND
AT43USB355
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