TL16C554A, TL16C554AI

ASYNCHRONOUS-COMMUNICATIONS ELEMENT

SLLS509E − AUGUST 2001 − REVISED JUNE 2010

7

POST OFFICE BOX 655303

Terminal Functions (Continued)

TERMINAL

NAME

FN

NO.

PM

NO.

PN

NO.

I/O

DESCRIPTION

RIA, RIB,

RIC, RID

19, 30,

50, 63

18, 43,

58, 3

I

Ring detect indicator. A low on RIx indicates the modem has received a ring signal from

the telephone line. The condition of this signal can be checked by reading bit 6 of the

modem-status register.

RTSA, RTSB,

RTSC, RTSD

5, 13,

36, 44

26, 35,

66, 75

O

Request to send. When active, RTS informs the modem or data set that the ACE is ready

to receive data. RTS is set to the active level by setting the RTS modem-control register

bit, and is set to the inactive (high) level either as a result of a master reset, or during

loop-mode operations, or by clearing bit 1 (RTS) of the MCR. In the auto-RTS mode, RTS

is set to the inactive level by the receiver threshold-control logic.

RXA, RXB

RXC, RXD

7, 29,

41, 63

20, 29,

51, 62

17, 44,

57, 4

I

Serial input. RXx is a serial-data input from a connected communications device. During

loopback mode, the RXx input is disabled from external connection and connected to the

TXx output internally.

RXRDY

38

54

O

Receive ready. RXRDY goes low when the receive FIFO is full. It can be used as a single

transfer or multitransfer.

TXA, TXB

TXC, TXD

17, 19,

51, 53

8, 10,

39, 41

29, 32,

69, 72

O

Transmit outputs. TXx is a composite serial-data output connected to a communications

device. TXA, TXB, TXC, and TXD are set to the marking (high) state as a result of reset.

TXRDY

39

55

O

Transmit ready. TXRDY goes low when the transmit FIFO is full. It can be used as a single

transfer or multitransfer function.

13, 30,

47, 64

21, 35,

52

5, 25,

45, 65

Power supply

XTAL1

35

25

50

I

Crystal input 1 or external clock input. A crystal can be connected to XTAL1 and XTAL2 to

utilize the internal oscillator circuit. An external clock can be connected to drive the

internal-clock circuits.

XTAL2

36

26

51

O

Crystal output 2 or buffered clock output (see XTAL1).

−0.5 V to 7 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

−0.5 V to 7 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Continuous total-power dissipation at (or below) 70

°C

500 mW

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0

°C to 70°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TL16C554AI

−40

°C to 85°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

−65

°C to 150°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not

implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

NOTE 1: All voltage levels are with respect to GND.