ISL81487

5V, Half Duplex, 5Mbps, RS-485/RS-422 Transceiver

OVERVIEW

These Renesas RS-485/RS-422 devices are “fractional” Unit Load (UL), 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 ISL81483 and ISL81487 present a 1/8 unit load to the RS-485 bus, which allows up to 256 transceivers on the network for large node count systems (for example, process automation, remote meter reading systems). In a remote utility meter reading system, individual (apartments for example) utility meter readings are routed to a concentrator through an RS-485 network, so the high allowed node count minimizes the number of repeaters required to network all the meters. Data for all meters is then read out from the concentrator using a single access port, or a wireless link. The slew rate limited driver on the ISL81483 reduces EMI, and minimizes reflections from improperly terminated transmission lines, or unterminated stubs in multidrop and multipoint applications. Data rates up to 250kbps are achievable with these devices.

Data rates up to 5Mbps are achievable by using the ISL81487, which features higher slew rates.

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

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.

These half duplex devices multiplex the Rx inputs and Tx outputs to allow transceivers with Rx and Tx disable functions in 8 Ld packages.

KEY FEATURES

    • Fractional unit load allows up to 256 devices on the bus
    • Specified for 10% tolerance supplies
    • Class 3 ESD protection (HBM) on all pins: >7kV
    • High data rate version (ISL81487): up to 5Mbps
    • Slew rate limited version for error free data transmission (ISL81483): up to 250kbps
    • Low current shutdown mode (except ISL81487): 0.5µA
    • Low quiescent supply current:
      - ISL81483: 145µA (Max.)
      - ISL81487: 420µA (Max.)
    • -7V to +12V common-mode input voltage range
    • Three state Rx and Tx outputs
    • 30ns propagation delays, 5ns skew (ISL81487)
    • Half duplex pinouts
    • Operate from a single +5V supply (10% tolerance)
    • Current limiting and thermal shutdown for driver overload protection
    • Drop-in replacements for: MAX1483 (ISL81483); MAX1487, LMS1487 (ISL81487)
    • Pb-free plus anneal available (RoHS compliant)

PARAMETRICS

Parameters
ISL81487
Basic Information
生产状态
Mass Production
关键特性
Low Cost
Tx数量
1
Rx数量
1
总线上允许的设备
256
半/全双工
Half
高ESD保护
No
热插拔
No
数据率
5 Mbps
供电电压Vcc (最小值) (V)
4.5
供电电压Vcc (最大值) (V)
5.5
受限压摆率
No
Tx/Rx启用
Yes
IS启用/禁用
400/350 µA
SHDN ICC
N/A µA
VL引脚
No
资质级别
Standard
供电电压Vcc范围 (V)
4.5 to 5.5
CAN 采样
YES
温度范围
-40 to +85

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