AT43301_05 ATMEL [ATMEL Corporation], AT43301_05 Datasheet - Page 11

• Manufacturer Part Number: AT43301_05
• Description: Low-cost USB Hub Controller
• Manufacturer: ATMEL [ATMEL Corporation]

2.8
2.9
1137J–USB–01/06
Status Pin
Power Supply
For proper operation of the PLL, an external RC filter consisting of a series RC network of 100Ω
and 10 nF in parallel with a 2 nF capacitor must be connected from the LFT pin to V
The status pin, STAT, is provided to allow feedback to the user. If an LED and a series resistor is
connected between STAT and VCC, the LED will light when the hub is enumerated. During an
overcurrent condition, the LED will blink. It will continue to blink until the host turns off the power
to the ports or until the hub is re-enumerated.
The I/O pins of the AT43301 should not be directly connected to voltages less than VSS or more
than the voltage at the CEXT pins. If it is necessary to violate this rule, insert a series resistor
between the I/O pin and the source of the external signal source that limits the current into the
I/O pin to less than 0.2 mA. Under no circumstance should the external voltage exceed 5.5V. To
do so will put the chip under excessive stress.
Figure 2-3.
The AT43301 is powered from the USB bus, but has an internal voltage regulator to supply the
3.3V operating power to its circuitry. For proper operation, an external high quality, low ESR,
0.27 µF, or larger, capacitor should be connected to the output of the regulator, CEXT1 and
ground. The CEXT1 pin can also be used to supply the voltage to the 1.5 kΩ pull up resistor at
Port 0’s DP pin.
To provide the best operating condition for the AT43301, careful consideration of the power sup-
ply connections are recommended. Use short, low impedance connections to all power supply
lines: V
ceramic capacitor soldered as close as possible to the VCC and VSS package pins are
recommended.
The AT43301 can also operate directly off a 3.3V power supply. In this case, leave the VCC pin
floating and connect the 3.3V power to CEXT1.
CC
and V
External Oscillator and PLL Circuit
SS
. Use sufficient decoupling capacitance to reduce noise: 0.1 µF of high quality
6.000 MHz
10nF
Y1
C1
100
R1
2nF
C2
U1
OSC1
OSC2
LFT
AT43301
AT43301
SS
.
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