AT43USB325E-AC Atmel, AT43USB325E-AC Datasheet - Page 90

• Manufacturer Part Number: AT43USB325E-AC
• Description: IC USB KEYBOARD CTRLR HUB 64LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB325E-AC

• Applications: Keyboard Controller
• Core Processor: AVR
• Program Memory Type: SRAM (16 kB)
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: SPI, 3-Wire Serial
• Number Of I /o: 42
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

8.4.5
8.4.6
8.4.7
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AT43USB325
Hub and Port Power Management
Overcurrent Sensing
Port Power Switching
Overcurrent protection and power switching are required for the external downstream ports only.
In the AT43USB325, these tasks are completely programmable. This means that any type of
hub is achievable with the AT43USB325: self-powered or bus-powered hubs, per port or global
overcurrent protection, individual or ganged port power switching.
The use of the MCU's GPIO pins are required to interface to the external power supply monitor-
ing and switching. The on-chip hardware of the AT43USB325 contains the circuitry to handle all
the possible combinations of port power management tasks. The firmware defines the exact
configuration.
The AT43USB325 is capable of detecting overcurrent during active operation only, or during any
condition even when the hub is in the suspended state. When overcurrent in the active state only
is desired, any GPIO pin of the AT43USB325 can be used to sense and the overcurrent condi-
tion. Control of the condition must be performed by the firmware. If overcurrent detection under
any condition is desired, then specific GPIO pins must be used to sense the overcurrent and the
proper bit(s) of UOVCER set. In Global Overcurrent Protection mode, overcurrent sensing must
be routed to GPIO PD0. In Individual Port Overcurrent Protection mode Port2 and Port 3 over-
current sensing must be assigned to GPIO PD0 and PD1. In the following description, it is
assumed that overcurrent protection is required under any condition.
1. Global Overcurrent Protection – In this mode, the Port Overcurrent Indicator and Port
2. Individual Port Overcurrent Protection – The Hub Overcurrent Indicator and Hub
1. Gang Power Switching – One of the microcontroller GPIO pins, PWRN, must be pro-
2. Individual Power Switching – Two microcontroller GPIO pins, PWR2N and PWR3N,
3. Multiple Ganged Overcurrent Protection – Overcurrent sensing is grouped physi-
Overcurrent Indicator Change should be set to 0's. For the AT43USB325 an external
solid state switch, such as the Micrel MIC2025-2, is required to switch power to the
external USB ports. The FLG output of the switch should be connected to PD0. When
an overcurrent occurs, FLG is asserted and the firmware should set the Hub Overcur-
rent Indicator and Hub Overcurrent Indicator Change and switch off power to all
external downstream ports. The hub status change is reported on the next IN token
through the hub's interrupt endpoint, Endpoint1.
Overcurrent Indicator Change bits should be set to 0's. One MIC2026-2 is required for
the two USB ports. The FLG output of the MIC2026-2 associated with Port2 should be
connected to GPIO PD0 and the other FLG output to PD1. An overcurrent is indicated
by assertion of FLG. The firmware sets the corresponding port's Overcurrent Indicator
and the Overcurrent Indicator Change bits and switches off power to the port. At the
next IN token from the Host, the AT43USB325 reports the port status change through
the hub's Endpoint1.
grammed as an output to control the external switch such as the MIC2025-2. Switch
ON is requested by the USB Host through the SetPortFeature(PORT_POWER)
request. Switch OFF is executed upon receipt of a ClearPortFeature(PORT_POWER)
or upon detecting an overcurrent condition. The firmware clears the Power Control Bit.
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.
3355C–USB–4/05