AT43USB325 datasheet(4/109 Pages) ATMEL

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3355C–USB–4/05

AT43USB325

1.3

Signal Description

Name

Type

Function

VCC1, 2

Power Supply/Ground

5V Power Supply

CEXT1, 2

Output

External Capacitors for Internal Voltage Regulator – A high quality 2.2µF capacitor must

be connected to CEXT1 and 0.33 µF to CEXT2 for proper operation of the chip.

VSS1, 2

Power Supply/Ground

Ground

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 pull-up resistor. DP0 and DM0 form the differential signal pin pairs connected to the

Host Controller or an upstream Hub.

DMO

Bi-directional

Upstream Minus USB I/O

DP[2:5]

Bi-directional

Port Plus USB I/O – Each of these pins should be connected to VSS through an external

15 k

Ω resistor. DP[2:5] and DM[2:5] are the differential signal pin pairs to connect

downstream USB devices.

DM[2:5]

Bi-directional

Port Minus USB I/O – Each of these pins should be connected to VSS through an external

15 k

Ω resistor.

PA[0:7]

Bi-directional

Port A[0:7] – Bi-directional 8-bit I/O port with controlled slew rate. These pins are used as

eight of the keyboard matrix column output strobes. PA[0:7] = COL[0:7].

PB[0:7]

Bi-directional

Port B[0:7] – Bi-directional 8-bit I/O port controlled slew rate. These pins are used

as the eight of the keyboard matrix column output strobes: PB[0:7] = COL[8:15].

PB0 has a dual function: the input to timer/counter0.

PC[0:7]

Bi-directional

Port C[0:7] – Bi-directional 8-bit I/O port with internal pull-ups. These pins are used as

keyboard matrix row input signals. PC[0:7] = ROW [0:7].

PD[0,1,3:7]

Bi-directional

Port D[0,1,3:7] – Bi-directional I/O ports. Port D[1,4:7] have dual functions as shown below:

PE[0:3]

Bi-directional

Port E[0:3] – Bi-directional I/O port with controlled slew rate which can be used as four

additional keyboard column output strobes, COL[16:19].

PE[4:7]

Bi-directional

PE[4:7] – Bi-directional I/O port. PE[4:7] have built-in series limiting resistors and can be

used to drive LEDs directly

Port Pin

Alternate Function

PB0

T0, Timer/Counter0 external input

Port Pin

Alternate Function

PD1

T1, Timer/Counter1 External Input

PD3

INT1, External Interrupt Input 1

PD4

INTA, External Interrupt Input A

PD5

INTB, External Interrupt Input B

PD6

INTC, External Interrupt Input C

PD7

INTD, External Interrupt Input D

AT43USB325 Datasheet(PDF) 4 Page - ATMEL Corporation

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