MAX3095 Maxim, MAX3095 Datasheet - Page 10

• Manufacturer Part Number: MAX3095
• Description: 15kV ESD-Protected / 10Mbps / 3V/5V / Quad RS-422/RS-485 Receivers
• Manufacturer: Maxim

±15kV ESD-Protected, 10Mbps, 3V/5V,
Quad RS-422/RS-485 Receivers
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.
The standard RS-485 input impedance is 12kΩ (one-
unit load). The standard RS-485 transmitter can drive
32 unit loads. The MAX3095/MAX3096 present a 1/4-
unit-load input impedance (48kΩ), 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.
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.
10
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Applications Information
Propagation-Delay Matching
128 Receivers on the Bus
Fail-Safe Implementation
Figure 6. External Fail-Safe Implementation
TRANSISTOR COUNT: 676
150
1k
1k
Chip Information
V
A
B
CC
MAX3095
MAX3096