4

AT43USB351M

3302CS–USB–2/04

Signal Description

Name

Type

Function

Power Supply/Ground

5V Digital Power Supply

Power Supply/Ground

5V Power Supply for the ADC

V

Power Supply/Ground

Digital Ground

V

SSA

Power Supply/Ground

Ground for the ADC

CEXT1,2

Power Supply/Ground

External Capacitors for Power Supplies – High quality 2.2 µF capacitors must be

connected to V331 and V332 for proper operation of the chip.

CEXT

Power Supply/Ground

External Capacitor for Analog Power Supply – A high quality 0.33 µF capacitor

must be connected to V33A for proper operation of the chip.

XTAL1

Input

Oscillator Input – Input to the inverting oscillator amplifier.

XTAL2

Output

Oscillator Output – Output of the inverting oscillator amplifier.

LFT

Input

PLL Filter – For proper operation of the PLL, this pin should be connected through

a 0.01 µF capacitor in parallel with a 100

Ω resistor in series with a 0.1 µF capacitor

to ground (VSS). Both capacitors must be high quality ceramic.

DPO

Bi-directional

Upstream Plus USB I/O – This pin should be connected to CEXT1 through an

external 1.5 k

Ω.

DMO

Bi-directional

Upstream Minus USB I/O

PA[0:7]

Bi-directional

Port A[0:7] – Bi-directional 8-bit I/O port with 2 mA drive strength and a

programmable pull-up resistor.

PB[4:7]

Bi-directional

Port B[4:7] – Bi-directional 8-bit I/O port with 2 mA drive strength and a

programmable pull-up resistor. PB[4:7] have dual functions as shown below:

Port Pin

Alternate Function

PB4

SSN, SPI Slave Port Select or SCL, I2C Serial Bus Clock

PB5

MOSI, SPI Slave Port Select Input

PB6

MISO, SPI Master Data In, Slave Data Out

PB7

SCK, SPI Master Clock Out, Slave Clock In

PD[0:6]

Bi-directional

Port D[0:6] – Bi-directional I/O ports with 2 mA drive strength and a programmable

pull-up resistor. PortD[2:6] have dual functions as shown below:

Port Pin

Alternate Function

PD2

INT0, External Interrupt 0

PD4

ICP, Timer/Counter, Input Capture

PD3

INT1, External Interrupt 1

PD5

OC1A Timer/Counter1 Output Compare A

PD6

OC1B Timer/Counter1 Output Compare B

ADC[0:11]

Input

ADC Input[0:11] – 12-bit input pins for the ADC.

TEST

Input

Test Pin – This pin should be tied to ground.

RESETN

Input

Reset – Active Low.

2XN

Input

Clock Frequency Selector (see Table 1 on page 6)