LTC1323CS View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LTC1323CS

Single 5V AppleTalk® Transceiver

Linear Technology 

U

W

SWITCHI G WAVEFOR S

VIH

RXI, RXI

VIL

VOH

RXI

VOL

1.5V f = 1MHz: tr ≤ 10ns: tf ≤ 10ns

tPHL

0.8V

VIH

RXI

1.5V

V

1.5V

tPLH

Figure 12. Single-Ended Receiver

3V

RXEN

0V

5V

RXO, RXO, RXDO

VOL

VOH

RXO, RXO, RXDO

0V

1.5V

tZL

tZH

1.5V

f = 1MHz: tr ≤ 10ns: tf ≤ 10ns

tLZ

2.3V

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

tHZ

2.3V

Figure 13. Receiver Enable and Disable

2.4V

1.5V

LTC1323 • F12

0.5V

0.5V

LTC1323 • F13

LTC1323

UU W U

APPLICATIO S I FOR ATIO

Functional Description

The “serial port” on the back of an Apple-compatible

computer or peripheral is a fairly versatile “multi-protocol”

connector. It must be able to connect to a wide bandwidth

LAN (an AppleTalk/LocalTalk network), which requires a

high speed differential transceiver to meet the AppleTalk

specification, and it must also be able to connect directly to

a printer or modem through a short RS232 style link. The

LTC1323 is designed to provide all the functions necessary

to implement such a port on a single chip. Two versions of

the LTC1323 are available: a 16-pin SO version which

provides the minimum solution for interfacing to an

AppleTalk network in a smaller package, and a larger 24-pin

SO Wide version which additionally includes all the hand-

shaking lines required to implement a complete AppleTalk/

modem/printer serial port. All LTC1323s run from a single

5V power supply while providing true single-ended com-

patibility, and include a 0.5µA low power shutdown mode

to improve lifetime in battery-powered devices. The 24-

pin SO Wide version also includes a receiver keep-alive

mode for monitoring external signals while drawing 65µA

typically.

The LTC1323 includes an RS422-compatible differential

driver/receiver pair for data transmission, with the driver

specified to drive 2V into the 100Ω primary of a typical

LocalTalk interface transformer/RFI interference network.

Either output of the differential RS422 driver can also act as

an single-ended driver, allowing the LTC1323 to commu-

nicate over a standard serial connection. The 24-pin SO

Wide LTC1323 also includes an extra single ended only

driver and two extra RS232-compatible single-ended re-

ceivers for handshaking lines. All versions include an on-

board charge pump to provide a regulated – 5V supply

required for the single-ended drivers. The charge pump

can also provide up to 10mA of external load current to

power other circuitry.

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