SN75LBC784 Datasheet | Texas Instruments

FEATURES D Four Independent Drivers and Receivers D Driver Slew Rate Controlled by a Single Resistor D Fast Driver Transition Times Down to 1.5 µs and Receiver Transition Times of 20 ns Typ D Internal Thermal-Overload Protection D RS-423-B Inputs and Outputs Designed to Withstand ± 25 V D ESD Protection Exceeds 2000 V Per MIL-STD-833C Method 3015 D Lin BICMOS Process Technology DESCRIPTION DW PACKAGE (TOP VIEW) 3A 3Z BIAS 4A 4Z BIAS VSS GND 4B 4Y 3B 3Y 3C 4C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 BIAS 27 2Z 26 2A 25 BIAS 24 1Z 23 1A 22 Rws 21 VDD 20 1Y 19 1B 18 2Y 17 2B 16 2C 15 1C The SN75LBC784 performs as four independent RS-423-B driver/receiver pairs designed to interface data terminal equipment (DTE) with data circuit-terminating equipment (DCE) at rates up to 120 kbps and distances to 1.2 km. The SN75LBC784 provides an upgrade to the RS-232 serial interface and can be backwards-patible with existing serial ports while offering the higher performance required by new faster peripherals, such as v.34 (v.fast) modems. The RS-232 standard, and subsequent revisions, only supports data rates up to 20 kbps over about 15 meters of cable. For RS-423-B the data rate is increased to 120 kbps and transmission distance to 1.2 km by reducing the maximum output signal swing, increasing the driver output current, and reducing the receiver input voltage thresholds. FUNCTION TABLE INPUTS A BC L LH HLH L HL H HL OUTPUTS HH HL LH LL L LL HLL L HH H HH ?H ?L ?H ?L H = high level, L = low level, X = irrelevant, Z = high impedance (off) ? = indeterminate The receivers consist of differential parators with hysteresis and resistive attenuation on the inputs. The resistive attenuation improves the input mon-mode range and also provides additional protection from ESD and over-voltage stress. The differential and mon-mode input impedances are sufficiently high to meet RS-423-B. When a differential voltage input of 500 m V is applied across the entire mon-mode range (see...