SN65LBC184

The SN75LBC184 and SN65LBC184 are differentialdata line transceivers in the trade-standardfootprint of theSN75176 with built-in protectionagainst high-energy noise transients. SN75LBC184 and SN65LBC184 feature provides a substantial increase in reliability forbetter immunity to noise transients coupled to thedata cable over most existing devices. Use ofthese circuits provides a reliable low-costdirect-coupled (with no isolation transformer) dataline interface without requiring any externalcomponents.

The SN75LBC184 and SN65LBC184 can withstandovervoltage transients of 400 W peak(typical). The conventional combination wavecalled out in CEI IEC 1000-4-5 simulates theovervoltage transient and models a unidirectional surge caused by overvoltages from switching andsecondary lightning transients.

A biexponential function of SN75LBC184 and SN65LBC184 defined by separate rise and fall times for voltage and current simulates thecombination wave. The standard 1.2 ms/50 ms combination waveform is shown in Figure 1 and in the testdescription in Figure 9.

The SN75LBC184 and SN65LBC184 also includes additional desirable features for party-line data buses in electrically noisy environmen tapplications including industrial process control. The differential-driver design incorporates slew-rate-controlled outputs sufficient to transmit data up to 250 kbits/s. Slew-rate control allows longer unterminated cable runs andlonger stub lengths from the main backbone than possible with uncontrolled and faster voltage transitions. Aunique receiver design provides a fail-safe output of a high level when the inputs are left floating (open circuit).The SN75LBC184 and SN65LBC184 receiver also includes a high input resistance equivalent to one-half unitload allowing connection of up to 64 similar devices on the bus.

The SN75LBC184 is characterized for operation from 0 to 70. The SN65LBC184 is characterized from40 to 85.