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PDF AT43312 Data sheet ( Hoja de datos )
| Número de pieza | AT43312 | |
| Descripción | Self- and Bus- Powered USB Hub Controller | |
| Fabricantes | ATMEL Corporation | |
| Logotipo |  |
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Features
• Full compliance with USB spec Rev 1.0
• Four downstream ports
• Full speed and low speed data transfers
• Self-Powered or Bus-Powered modes of operation
• Per port overcurrent monitoring
• Individual port power switch control
• USB connection status indicators
Description
The AT43312 is a 5 port USB hub chip supporting one upstream and four downstream
ports. The AT43312 connects to an upstream hub or Host/Root Hub via Port0 and the
other ports connect to external downstream USB devices. The hub re-transmits the
USB differential signal between Port0 and Ports[1:4] in both directions. A USB hub
with the AT43312 can operate as a bus-powered or self-powered through chip’s
power mode configuration pin. The AT43312 is pin- and function-compatible with the
AT43311 and can be used as a replacement for the AT43310 with one pin modifica-
tion.
The AT43312 supports the 12 Mb/s full-speed as well as 1.5 Mb/s slow-speed USB
transactions. To reduce EMI, the AT43312’s oscillator frequency is 6 MHz even
though some internal circuitry operates at 48 MHz.
Self- and Bus-
Powered USB
Hub Controller
AT43312
Pin Configurations
SOIC/DIP
PWR2
PWR3
PWR4
VCC5
GND
OSC1
OSC2
LFT
VCCA
OVL4
OVL3
OVL2
OVL1
VREF
BUS/SELF
STAT4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32 PWR1
31 DP4
30 DM4
29 DP3
28 DM3
27 GND
26 DP2
25 DM2
24 VCC3
23 DP1
22 DM1
21 DP0
20 DM0
19 STAT1
18 STAT2
17 STAT3
Rev. 1002A-A–01/98
1
1 page  
AT43312
from the host. PWRx is de-asserted under the following
conditions:
1. Power up
2. Reset and initialization
3. Overcurrent condition
Self-powered Mode
In the self-powered mode, power to the downstream ports
must be supplied by an external power supply. This power
supply must be capable of supplying 500 mA per port.
The USB specifications require that the voltage drop at the
power switch, and board traces be no more than 100 mV. A
good conservative maximum drop at the power switch itself
should be no more than 750 mV. Careful design and selec-
Figure 2. Self-Powered Hub Power Supply
tion of the power switch and PC board layout is required to
meet the specifications. When using a MOSFET switch, its
resistance must be 140 MΩ or less, under worst case con-
ditions. A suitable MOSFET switch for an AT43312 based
hub is a P-channel enhancement mode MOSFET. The
input of the PMOS switch is connected to the local 5V
power supply while the output is connected to the port
power line, as well as the port’s OVCx pin. An overcurrent
condition increases the voltage drop across the MOSFET.
If this voltage drops to less than the voltage at VREF, the
AT43312 voltage reference pin, the AT43312 interpretes
this as an overcurrent condition. The AT43312 removes the
power from that port by de-activating the port’s PWRx pin
and reports the condition to the Host.
3V REG
BUS_POWER
GND
IN OUT
GND
POWER SUPPLY
5V OUT
GND
VCC5 GND VCC3
R1
VREF AT43312
R2
PWR
MOSFET P
OVC DM DP
DP
DM
PORT_POWER
GND
To
downstream
device
Bus-powered Mode
In the bus-powered mode, all the power for the hub itself as
well as the downstream ports are supplied by the root hub
or upstream hub through the USB. Only 100 mA is avail-
able for each of the hub’s downstream devices and there-
fore only low power devices are supported.
The power switch and overcurrent protection work exactly
like the self-powered mode, except that the allowable
switch resistance is higher: 700 MΩ or less under the
worst-case condition.
The diagrams of Figures 2 and 3 show examples of the
power supply and management connections for a typical
AT43312 port in the self-powered mode and bus-powered
mode.
5
5 Page 
AT43312
Endpoint Descriptor
There is no endpoint descriptor for Endpoint0. This descriptor describes the Endpoint1 descriptor which the Hub uses for
status change report.
Offset Field
Description
Size (bytes) Value
0 bLength
Size of this descriptor = 7 bytes.
1 0x07
1 bDescriptorType Descriptor type = Endpoint
1 0x05
2
bEndpointAddress
The address of the IN endpoint
1 0x81
3 bmAttributes
Transfer Type = Interrupt
1 0x03
4
wMaxPacketSize
Max. packet size Endpoint1 is capable of sending = 1 byte
2 0x01
0x00
6 bInterval
Interval for polling endpoint for data transfers = 256 ms
1 0xFF
Hub Descriptor
This descriptor describes the AT43312’s Hub and ports.
Offset
0
1
2
3
5
6
7
8
Field
bDescLength
bDescriptor Type
bNbrPorts
wHubCharacteristics
bPwrOn2PwrGood
bHubContrCurrent
DeviceRemovable
PortPwrCtrlMask
Definition
Define size of this descriptor = 9 bytes
Descriptor Type = HUB_DESCRIPTOR = 29
Number of downstream ports = 4
Hub's characteristics:
= Individual power switching
= Hub is not part of a compound device
= Individual Port Over-current Protection
Time from the time power-on sequence begins on a port until power is
good on that port = 100ms.
Maximum current requirements of the hub electronics = 100 mA.
Indicates if a port has removeable device. All downstream ports have
removable devices.
Indicates if a port is not affected by gang-mode power control request. All
the AT43312’s ports require manual SetPortFeature(PORT_POWER)
request to control the port’s power state.
Size (bytes)
1
1
1
2
Value
0x09
0x29
0x04
0x09
0x00
1 0x32
1 0x64
1 0x00
1 0x1E
11
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet AT43312.PDF ] | |
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