TABLE 1. Device Pin Descriptions

Pin

No.

Name

Description

1

RO

Receiver Output: When RE (Receiver Enable) is LOW, the receiver is enabled (ON), if DO/RI

≥ DO

(Note 1)/RI (Note 1) by 200 mV, RO will be HIGH. If DO/RI

≤ DO (Note 1)/RI (Note 1) by 200 mV,

RO will be LOW. Additionally RO will be HIGH for OPEN (Non-terminated) Inputs.

2RE

(Note 1)

Receiver Output Enable: When RE (Note 1) is LOW the receiver output is enabled. When RE (Note

1) is HIGH, the receiver output is in TRI-STATE (OFF). When RE (Note 1) is HIGH and DE is LOW,

the device will enter a low-current sleep mode after 600 ns.

3

DE

Driver Output Enable: When DE is HIGH, the driver outputs are enabled. When DE is LOW, the

driver outputs are in TRI-STATE (OFF). When RE (Note 1) is HIGH and DE is LOW, the device will

enter a low-current sleep mode after 600 ns.

4

DI

Driver Input: When DE (Driver Enable) is HIGH, the driver is enabled, if DI is LOW, then DO/RI will

be LOW and DO (Note 1)/RI (Note 1) will be HIGH. If DI is HIGH, then DO/RI is HIGH and DO (Note

1)/RI (Note 1) is LOW.

5

GND

Ground Connection.

6

DO/RI

Driver Output/Receiver Input, 485 Bus Pin.

7DO

(Note 1)

/RI

(Note 1)

Driver Output/Receiver Input, 485 Bus Pin.

8V

CC

Positive Power Supply Connection: Recommended operating range for V

Unit Load

A unit load for an RS-485 receiver is defined by the input

current versus the input voltage curve. The gray shaded

region is the defined operating range from −7V to +12V. The

top border extending from −3V at 0 mA to +12V at +1 mA is

defined as one unit load. Likewise, the bottom border ex-

tending from +5V at 0 mA to −7V at −0.8 mA is also defined

as one unit load (see Figure 15 ). An RS-485 driver is

capable of driving up to 32 unit loads. This allows up to 32

nodes on a single bus. Although sufficient for many applica-

tions, it is sometimes desirable to have even more nodes.

guaranteed over temperature.

Figure 15 are scaled. Both 0 mA reference points at +5V and

−3V stay the same. The other reference points are +12V at

+0.5 mA for the top border and −7V at −0.4 mA for the

bottom border (see Figure 15 ). Again, both 0 mA reference

points at +5V and −3V stay the same. The other reference

points are +12V at +0.25 mA for the top border and −7V at

−0.2 mA for the bottom border (see Figure 15 ).

01291915

*Note: Non Terminated, Open Input only

FIGURE 14. Entering Sleep Mode Conditions (modes and exit parameters shown)

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