±15kV ESD-Protected, 32Mbps, 3V/5V,

Triple RS-422/RS-485 Receivers with Fault Detection

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7

(FAULT OUTPUT)

ALARMA

OR

ALARMD

A

A

OUTA

Figure 1. Typical Receiver Test Circuit

+3V

OV

OV

RISE/FALL TIMES

≤2ns

-3V

Figure 2. Propagation Delay

OV

-3.0V

+3.0V

ALARM OR ALARMD

Figure 3. Fault-Detection Timing

OV

ALARM OR ALARMD

Figure 4. Common-Mode Fault Propagation Delay

Test Circuits and Waveforms

Detailed Description

The MAX3097E/MAX3098E feature high-speed, triple

RS-485/RS-422 receivers with fault-detection circuitry

and fault-status outputs. The fault outputs are active

push-pull, requiring no pull-up resistors. The fault cir-

cuitry includes a capacitor-programmable delayed

FAULT_ output to ensure that there are no erroneous

fault conditions even at slow edge rates (see Delayed

Fault Output). The receivers operate at data rates up to

32Mbps.

The MAX3097E/MAX3098E are designed for motor-

shaft encoders with standard A, B, and Z outputs (see

Using the MAX3097E/MAX3098E as Shaft Encoder

Receivers). The devices provide an alarm for open-cir-

cuit conditions, short-circuit conditions, data nearing

the minimum differential threshold conditions, data

below the minimum threshold conditions, and receiver

inputs outside the input common-mode range. Tables 1

and 2 are functional tables for each receiver.