AT43USB326-AU Atmel, AT43USB326-AU Datasheet - Page 72

• Manufacturer Part Number: AT43USB326-AU
• Description: IC USB KEYBOARD CTRLR 48LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB326-AU

• Applications: Keyboard Controller
• Core Processor: AVR
• Program Memory Type: Mask ROM (16 kB)
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: USB
• Number Of I /o: 32
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 12. Port Power Management
Suspend and
Resume
72
AT43USB326
BUS_POWER
GND
Figure 12 shows a simplified diagram of a power management circuit of an AT43USB326
based hub design with global overcurrent protection and ganged power switching for the two
external downstream ports.
The over-current protection and port power switching for the AT43USB326 is best imple-
mented in the so-called multiple gang. The Hub Characteristic’s bits in the Hub Descriptor are
set as follows:
•
•
When an over-current condition at one of the external ports is detected, the over-current bits of
both external ports are set. The host will switch off power to the external port, but the keyboard
will continue to operate. The external port power is switched on as soon as one port's power is
enabled, but switched off only when the power to both ports is disabled.
The AT43USB326 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.
Logical Power Switching is Individual, D1D0 = 01
Overcurrent Protection is Individual, D4D3 = 01
PWRN
IN
CTL
GND
SWITCH
AT43USB326
OVCN
FLG
OUT
VCC
PORT2_POWER
PORT3_POWER
PORT2_GND
PORT3_GND
3313D–USB–04/06