ISL8485

5V, Half Duplex, Low Power, High Speed, RS-485/RS-422 Transceivers

OVERVIEW

The ISL8485, ISL8490, and ISL8491 RS-485 / RS-422 devices are BiCMOS 5V powered, single transceivers that meet both the RS-485 and RS-422 standards for balanced communication. Unlike competitive devices, this family is specified for 10% tolerance supplies (4.5V to 5.5V).

The ISL8485, ISL8490, and ISL8491 feature data rates up to 5Mbps.

All devices present a single unit load to the RS-485 bus, which allows up to 32 transceivers on the network.

The receiver (Rx) inputs feature a “fail-safe if open” design, which ensures a logic high Rx output if the Rx inputs are floating.

The driver (Tx) outputs are short-circuit protected, even for voltages exceeding the power supply voltage. Additionally, on-chip thermal shutdown circuitry disables the Tx outputs to prevent damage if power dissipation becomes excessive.

The ISL8490 and ISL8491 are configured for full duplex (separate Rx input and Tx output pins) applications. Half duplex configurations (ISL8485) multiplex the Rx inputs and Tx outputs to allow transceivers with Rx and Tx disable functions in 8 Ld packages.

KEY FEATURES

    • Specified for 10% tolerance supplies
    • Class 3 ESD protection (HBM) on all pins: 7kV
    • High data rates: up to 5Mbps
    • Single unit load allows up to 32 devices on the bus
    • Low quiescent current: 500µA
    • -7V to +12V common-mode input voltage range
    • Three state Rx and Tx outputs (except ISL8490)
    • 30ns propagation delays, 5ns skew
    • Full duplex and half duplex pinouts
    • Operation from a single +5V supply (10% tolerance)
    • Current limiting and thermal shutdown for driver overload protection
    • Pb-free plus anneal (RoHS compliant)

PARAMETRICS

Parameters
ISL8485
Basic Information
Production Status
Mass Production(*)
Key Feature
Low Cost
# of Tx
1
# of Rx
1
Devices Allowed on Bus
32
Half/Full Duplex
Half
High ESD Protection
No
Hot Plug
No
Data Rate
5 Mbps
Supply Voltage Vcc (Min) (V)
4.5
Supply Voltage Vcc (Max) (V)
5.5
Slew Rate Limited
No
Tx/Rx Enable
Yes
IS Enabled/Disabled
550/340 µA
SHDN ICC
N/A µA
VL Pin
No
Qualification Level
Standard
Supply Voltage Vcc Range (V)
4.5 to 5.5
Can Sample
YES
Temperature Range
-40 to +85

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