6

LTC1348

Figure 1. Driver Propagation Delay Timing

Figure 2. Receiver Propagation Delay Timing

SWITCHI G TI E WAVEFOR S

1.4V

0V

0V

0V

DRIVER

INPUT

DRIVER

OUTPUT

1.4V

LTC1348 • F01

0.8V

0V

2.4V

RX

INPUT

RX

OUTPUT

1.3V

1.7V

LTC1348 • F02

0V

TEST CIRCUITS

Figure 3. Driver Timing Test Load

RX

RX INPUT

51pF

RX

OUTPUT

LTC1348 • F04

Figure 4. Receiver Timing Test Load

DRIVER

DRIVER

INPUT

3k

51pF

DRIVER

OUTPUT

LTC1348 • F03

Power Supply

The LTC1348 includes an onboard voltage-tripling charge

pump capable of generating

±8V from a single 3.3V

supply. This allows the LTC1348 drivers to provide guar-

anteed

±5V RS232-compliant voltage levels with a 3.3V

supply. With all outputs loaded with 3k

Ω, the LTC1348

can typically swing

±5V with voltages as low as 2.85V. It

will meet the

±3.7V EIA562 levels with supply voltages as

low as 2.2V. The charge pump requires three external

flying capacitors to operate; 0.1

µF ceramic capacitors are

adequate for most applications. For applications requiring

extremely high data rates or abnormally heavy output

loads, 0.33

µF flying capacitors are recommended. Bypass

and output capacitor values should match those of the

flying capacitors and all capacitors should be mounted as

close to the package as possible.

LT1348 • TC

RS232 LINE PINS

PROTECTED TO

±10kV

0.1

µF

0.1

µF

0.1

µF

0.1

µF

0.1

µF

LTC1348

1

2

3

4

5

6

7

8

9

10

11

12

13

14

DR1 OUT

RX1 IN

DR2 OUT

RX2 IN

RX3 IN

RX4 IN

DR3 OUT

RX5 IN

28

27

26

25

24

23

22

21

20

19

18

17

16

15

DR1 IN

RX1 OUT

DR2 IN

RX2 OUT

RX3 OUT

RX4 OUT

DR3 IN

RX5 OUT

DREN

RXEN

GND

0.1

µF

ESD Test Circuit