sents the minimum parasitic capacitance that would

exist in a typical application. In most cases, more

capacitance exists in the system and reduces the mag-

nitude of the glitch. During a “hot-swap” event when the

driver is connected to the line and is powered up, the

driver must not cause the differential signal to drop

below 200mV (Figures 12 and 13).

Operation of Enable Pins

The MAX3030E–MAX3033E family has two enable-func-

tional versions.

The MAX3030E/MAX3031E are compatible with

26LS31, where the two enable signals control all four

transmitters (global enable).

The MAX3032E/MAX3033E are compatible with the

SN75174. EN1&2 controls transmitters 1 and 2, and EN

3&4 controls transmitters 3 and 4 (dual enable).

Typical Applications

The MAX3030E–MAX3033E offer optimum performance

when used with the MAX3094E/MAX3096 3.3V quad

differential line receivers. Figure 14 shows a typical RS-

422 connection for transmitting and receiving data.

±15kV ESD-Protected, 3.3V Quad

RS-422 Transmitters

10

______________________________________________________________________________________

4

µs/div

DO_+

DO_+ - DO_-

DO_-

1V/div

Figure 12. Differential Power-Up Glitch (0.1V/µs)

1.0

µs/div

DO_+

DO_+ - DO_-

DO_-

1V/div

Figure 13. Differential Power-Up Glitch (1V/µs)

EN

EN

TX1

TX2

TX3

TX4

MODE

0

0

Active

Active

Active

Active

All transmitters active

0

1

High-Z

High-Z

High-Z

High-Z

All transmitters disabled

1

0

Active

Active

Active

Active

All transmitters active

1

1

Active

Active

Active

Active

All transmitters active

Table 1. MAX3030E/MAX3031E Transmitter Controls

EN1&2

EN3&4

TX1

TX2

TX3

TX4

MODE

0

0

High-Z

High-Z

High-Z

High-Z

All transmitters disabled

0

1

High-Z

High-Z

Active

Active

Tx 3 and 4 active

1

0

Active

Active

High-Z

High-Z

Tx 1 and 2 active

1

1

Active

Active

Active

Active

All transmitters active

Table 2. MAX3032E/MAX3033E Transmitter Controls