1
Features
• Full Compliance with USB Spec Rev 1.1
• Four Downstream Ports
• Full-speed and Low-speed Data Transfers
• Bus-powered Controller
• Bus-powered or Self-powered Hub Operation
• Per Port Overcurrent Monitoring
• Individual Port Power Control
• USB Connection Status Indicators
• 5V Operation with On-chip 3.3V Format
• 32-lead SOIC and LQFP
Overview
Introduction
The AT43312A is a 5 port USB hub chip supporting one upstream and four down-
stream ports. The AT43312A connects to an upstream hub or Host/Root Hub via Port0
and the other ports connect to external downstream USB devices. The hub re-trans-
mits the USB differential signal between Port0 and Ports[1:4] in both directions. A USB
hub with the AT43312A can operate as a bus-powered or self-powered through chip’s
power mode configuration pin. In the self-powered mode, port power can be switched
or unswitched. Overcurrent reporting and port power control can be individual or glo-
bal. An on-chip power supply eliminates the need for an external 3.3V supply.
The AT43312A supports the 12-Mb/sec full speed as well as 1.5-Mb/sec slow speed
USB transactions. To reduce EMI, the AT43312A’s oscillator frequency is 6 MHz even
though some internal circuitry operates at 48 MHz.
The AT43312A consists of a Serial Interface Engine, a Hub Repeater, and a Hub
Controller.
Self- and Bus-
powered USB
Hub Controller
AT43312A
Rev. 1255F–USB–3/04
SOIC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
PWR2
PWR3
PWR4
VCC5
VSS
OSC1
OSC2
LFT
TEST
OVC4
OVC3
OVC2
OVC1
LPSTAT
SELF/BUS
STAT4
PWR1
DP4
DM4
DP3
DM3
VSS
DP2
DM2
CEXT
DP1
DM1
DP0
DM0
STAT1
STAT2
STAT3
LQFP Top View
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
DP3
DM4
DP4
PWR1
PWR2
PWR3
PWR4
VCC5
DMO
STAT1
STAT2
STAT3
STAT4
SELF/BUS
LPSTAT
OVC1
32
31
30
29
28
27
26
25
9
10
11
12
13
14
15
16
VSS
OSC1
OSC2
LFT
TEST
OVC4
OVC3
OVC2
DM3
VSS
DP2
DM2
CEXT
DP1
DM1
DP0
