AT43301 View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT43301

Low-cost USB Hub Controller

Atmel Corporation 

AT43301

2.8 Status Pin

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 VSS.

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. External Oscillator and PLL Circuit

U1

Y1

6.000 MHz

R1

100

C1

10nF

OSC1

OSC2 AT43301

LFT

C2

2nF

2.9 Power Supply

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: VCC and VSS. Use sufficient decoupling capacitance to reduce noise: 0.1 µF of high quality

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.

11

1137J–USB–01/06

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