Applications Information

Propagation-Delay Matching

The MAX3095/MAX3096 exhibit propagation delays that

are closely matched from one device to another, even

between devices from different production lots. This fea-

ture allows multiple data lines to receive data and clock

signals with minimal skewing with respect to each other.

The MAX3095 receiver propagation delays are trimmed

to a predetermined value ±8ns, while the MAX3096

delays are trimmed to a predetermined value ±10ns.

128 Receivers on the Bus

The standard RS-485 input impedance is 12k

Ω (one-

unit load). The standard RS-485 transmitter can drive

32 unit loads. The MAX3095/MAX3096 present a 1/4-

unit-load input impedance (48k

Ω), which allows up to

128 receivers on a bus. Any combination of these RS-

485 receivers with a total of 32 unit loads can be con-

nected to the same bus.

Fail-Safe Implementation

The MAX3095/MAX3096 receiver inputs guarantee a

logic high output when the inputs are open circuit (no

termination resistor used). This occurs when the trans-

mitter is removed from the bus or when all transmitter

outputs are high impedance. However, when the line is

terminated and the transmitters are disabled, the differ-

ential voltage between the A and B inputs falls below

the ±200mV RS-485 sensitivity threshold. Consequent-

ly, the outputs become undefined. To maintain a fail-

safe receiver output while using a terminating resistor,

input A must be biased at least 200mV above input B.

The resistor-divider network shown in Figure 6 is rec-

ommended.

±15kV ESD-Protected, 10Mbps, 3V/5V,

Quad RS-422/RS-485 Receivers

10

______________________________________________________________________________________

1k

1k

150

Ω

MAX3095

MAX3096

A

B

Figure 6. External Fail-Safe Implementation

TRANSISTOR COUNT: 676

Chip Information