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| Corporation SP304 RS-232/RS-422 Line Drivers/Receivers SIGNAL PROCESSING EXCELLENCE s s s s s s RS-232 and RS-422 on One Chip Multiple Drivers and Receivers Software-selectable Modes Loopback for Self-Testing Short-circuit Protected Single-width 24-pin DIP and 28-pin SOIC Packages DESCRIPTION... The SP304 is an enhanced-performance version of the Sipex SP302 RS-232 and RS-422 protocol line drivers and receivers. It is pin-for-pin compatible with the SP302, and in any configuration, fully meets the requirements of the EIA RS-232D and RS-422 data communication standards. A loopback test mode is provided.The SP304 is available in 24-pin single width plastic DIP, and 28-pin SOIC packages for commercial and industrial temperature range operation. TOB1 TOB2 TOA1 TOA2 RIB1 RIB2 RIA1 RIA2 VDD VCC VEE GND SELECT A B LOOP- BACK SP304 TIB1 TIB2 TIA1 ROB1 ROB2 ROA1 Corporation 77 SIGNAL PROCESSING EXCELLENCE SPECIFICATIONS (TMIN TA TMAX and nominal supply voltages unless otherwise noted) PARAMETER RS-232 DRIVER TTL Input Level V V High Level Output Low Level Output Short Circuit Current Loopback Output Voltage Slew rate IL IH MIN. TYP. MAX. UNITS CONDITIONS 0 2.0 +5.0 -1.5 0.8 -5.0 30 30 3 V V V V mA V V/s s kbps Transition Time Maximum Transmission Rate 200 RS-232 RECEIVER Input Voltage Range -15 Input High Threshold +1.75 Input Low Threshold +0.75 Input Impedance 3 TTL Output Level V V 2.4 Maximum Receiving Rate 200 RS-422 DRIVER TTL Input Level V 0 V 2.0 High Level Output 2.75 Low Level Output Differential Output 2 OL OH IL IH R = 3k, V = 0.8V R = 3k, V = 2.0V V = 0V R = 3k, V = -12.0V; Note 1 C = 50pF, R = 3k; T = 25C V from +3V to -3V or -3V to +3V L IN L IN OUT L EE L L A OUT +15 +2.5 +1.35 7 0.4 V V V k V V kbps Note 6 Positive-going Negative-going V = +4.75V, I = +1.6mA V = +4.75V, I = -0.5mA CC OUT CC OUT 0.8 6.0 1.0 6 100 500 400 Short Circuit Current Output Current Transition Time Maximum Transmission Rate 1,000 RS-422 RECEIVER Common Mode Range Differential Input Differential Input Threshold -0.2 Input Voltage Hysteresis 30 Input Resistance 3 TTL Output Level V V 2.4 Maximum Receiving Rate 1,000 Short Circuit Output Current POWER REQUIREMENTS V = +12V, 10% V = +5V, 10% V = -12V, 10% ENVIRONMENTAL Operating Temperature -CS 0 -MR -55 Storage Temperature -65 OL OH DD CC EE V V V V V V mA A ns kbps V V V mV k V V kbps mA mA mA mA I = -20mA I = +20mA R = 100 R = Note 2 -0.25V V 6V; power off R = 100, C = 15pF; Note 3 OH OL L L O L L 7 15 +0.2 Note 4 Note 4 T = 25C V = 0V; T = 25C -7V V +7V A CM A CM 0.4 120 7 5 11 15 7 20 V = +4.75V, I = +1.6mA V = +4.75V, I = -0.5mA CC OUT CC OUT V = 0V OUT Note 5 Note 5 Note 5 +70 +125 +150 C C C 78 Corporation SIGNAL PROCESSING EXCELLENCE Notes: 1. 2. 3. 4. 5. In Loopback mode Only one output drive pin per package will be shorted at any time From 10% to 90% of steady-state This is an absolute maximum rating; normal operating levels are V < 5V Outputs unloaded; Inputs tied to GND; T = +25C; V = 0V; LB=0 Typical SP304 current drains under full load are: 18mA (+12V), 10mA (-12V) and 7mA (+5V) in RS-232 mode only; 5mA (+12V), 7mA (-12V) and 56mA (+5V) in RS-422 mode only; 12mA (+12V), 14mA (-12V) and 31mA (+5V) in RS-232 and RS-422 modes; RS232 loads 3k, 2500pF, 20kHz; RS422 outputs across 100, 500kHz. IN A IL TYPICAL PERFORMANCE CURVES RS-232 Driver RS-232 Receiver T IN 5V GND 10V GND -10V 20kHz RIN 5V GND -5V T OUT ROUT 5V GND 20kHz RS-422 Driver RS-422 Receiver 2V TIN GND TOUT 5V GND -5V RIN 2V GND -2V ROUT 5V GND 500kHz 500kHz Corporation 79 SIGNAL PROCESSING EXCELLENCE PIN ASSIGNMENTS VDD (+12V) 1 RIA2 2 RIA1 3 TOA2 4 TOA1 5 SELECT A 6 SELECT B 7 TOB1 8 TOB2 9 RIB1 10 RIB2 11 GND 12 24 VCC (+5V) 23 ROA2 22 ROA1 21 TIA2 20 TIA1 19 LB 18 N.C. 17 TIB1 16 TIB2 15 ROB1 14 ROB2 13 VEE (-12V) VDD (+12V) 1 RIA2 2 RIA1 3 N.C. 4 TOA2 5 TOA1 6 SELECT A 7 SELECT B 8 TOB1 9 TOB2 10 N.C. 11 RIB1 12 RIB2 13 GND 14 28 VCC (+5V) 27 ROA2 26 ROA1 25 N.C. 24 TIA2 23 TIA1 22 LB 21 N.C. 20 TIB1 19 TIB2 18 N.C. 17 ROB1 16 ROB2 15 VEE (-12V) FEATURES... The SP304 is a proprietary single-chip device that contain both RS-232 and RS-422 protocol line drivers and receivers. It is pin-for-pin compatible with the Sipex SP302. Like the SP302, its configuration may be changed at any time by logic levels on two control lines. In any configuration, the SP304 fully meets the requirements of both the EIA RS-232D and RS-422 data communication standards. The SP304 enhancements include improved isolation from external signals and a true high-impedance driver output in the loopback test mode, and no power up sequence requirements. The RS-232 line driver circuits convert TTL logic level inputs into inverted RS-232 output signals. The RS-422 line drivers convert TTL logic levels into RS-422 differential output signals. The RS-422 line driver outputs feature high source and sink current capability. All line drivers are internally protected against short circuits on their outputs. The RS-232 receivers convert the EIA RS-232 input signals to inverted TTL output logic levels. The RS-422 receivers convert the EIA RS422 differential input signals into non-inverted TTL output logic levels. Receiver input filtering provides excellent high frequency noise immunity. Input pulses with widths less than 1s are completely ignored. The RS-232 receivers have the additional feature of voltage hysteresis, which helps eliminate spurious output transitions that SP304CS might result from low amplitude noise voltages during slower-speed signal transitions. A loopback test mode is provided that puts the driver outputs to a high impedance tri-state level, and routes the driver outputs to their associated receiver inputs. In this configuration, the signal path is non-inverting from the TTL driver input to the receiver TTL output. This operating mode allows the controlling system to perform diagnostic self-test of the RS-232/ RS-422 driver/receiver circuitry at speeds up to 3,000 bits per second. In the loopback mode a 13.2V input range may be applied to the receiver inputs with no interference to the loopback test. In addition, the driver outputs are in a true high-impedance state during loopback. The SP304 is available in 24-pin single width (0.300") plastic DIP and 28-pin SOIC packages, for operation over the commercial and industrial temperature ranges. USING THE SP304 POWER SUPPLIES The SP304 requires 12V and +5V for full RS-232 and RS-422 operation. The 12V supplies set up the RS-232 9V voltage swings, and the +5V is used for the internal logic that formats the communications mode and controls the loopback function. The supply voltages can be decreased to as low as 7V for VDD and V EE, and SP304CT 80 Corporation SIGNAL PROCESSING EXCELLENCE VDD VDD VCC VCC 3.3k SP304 GND VEE VEE 3.3k 2N2222 Q3 Q4 a) Single SP304 b) Multiple SP304 VDD VDD VCC VCC 3.3k SP304 GND VDD VEE VCC VEE SP304 3.3k 2N2222 Q3 Q4 GND VEE transmission line with other RS-232 devices which are not powered by the same power supplies, it is possible that a device that is not powered will have a low impedance path to ground at its driver output. The RS-232 standards require that with no power applied to the device, the impedance from a transmitter output to ground must be greater than 300. This can be easily achieved as shown in Figure 1a, where an external transistor is used as a switch to isolate an SP304 from ground in the power off condition. With VDD turned on, the transistor switch is on, connecting ground (GND) for the device to the circuit ground. In a power-off condition, this transistor is switched off, thus isolating the unit from circuit ground, and thereby leaving the driver in a high impedance state. Multiple SP304s can be connected as shown in Figure 1b. RS-422 OPERATION The SP304 is a fully compliant RS-422 device when operating in the RS-422 mode. Baud rate and drive capability have been balanced to provide as much versatility as possible. The SP304 is both guaranteed for a 1Mbps data rate, Figure 1. Isolating the SP304 from Ground. +4.0V for VCC. Under these supply conditions, derated performance can be expected. POWER SUPPLY SEQUENCING There are no special power-up sequencing requirements for the SP304. GENERAL USAGE RS-232 Operation The SP304 is a fully compliant RS-232 device. Its outputs are fully protected against shorts to 20V with no external circuitry. If the potential exists for momentary shorts to voltages greater than 20V, it is recommended that a 220 resistor be wired in series with each driver output. This will limit any damage from the higher short-circuit current from these higher voltage potentials. Voltage clamps such as backto-back Zener diodes can be used to clamp the driver outputs to "safe" levels. Short circuit current to ground is internally limited, and can therefore be sustained infinitely. Under normal operating conditions, the drivers can typically source 7mA at 5V output, which exceeds the minimum RS-232 standards requirement. If an SP304 transmitter output occupies a data VDD VDD 3.3K GND 3.3K VCC VEE VCC VEE SELECT A = 1 SP304 2N2222 Q3 Q4 TIB1 SELECT B = 0 LOOPBACK = 1 TOB1 TIB2 TOB2 TOA1 TOA2 TIA1 ROB1 RIB1 ROB2 RIB2 RIA1 RIA2 ROA1 Figure 2. Typical Circuit Corporation 81 SIGNAL PROCESSING EXCELLENCE supplying 2V minimum into a 100 load. Short circuit protection for the RS-422 operating mode is the same as in the RS-232 mode. The driver outputs can be shorted to ground for an infinite duration, with a maximum current of 100mA. The RS-422 receivers accept differential signals at a 1Mbps rate, and translate them to a noninverted TTL output. The receivers are specified with a 15V differential input voltage, which means that to operate normally, the difference betweeen the voltages at the inputs cannot exceed 15V. The common mode voltage is specified as 7V. This identifies the midpoint of the range about which the differential input must lie so that the receiver can detect a change of state. Within this 7V range, the receivers will recognize a change in state with a 200mV differential threshold voltage. Since the RS-232 and RS-422 inputs are shared, all receiver inputs are protected to 30V to guard against inadvertently applying an RS-232 signal to an input that is configured for RS-422. Figure 2 shows a typical circuit for the SP304. In this case the SP304 is shown configured for one (1) duplex RS-422 and two (2) duplex RS-232 communication paths. CONFIGURING THE SP304 Figures 3, 4 and 5 show the various combinations of simultaneous RS-232 and RS-422 operation that can be achieved with the SP304. Each of these configurations are software selectable by logic level on the SELECT A and SELECT B control lines. Configuration can be changed "on-the-fly". 82 Corporation SIGNAL PROCESSING EXCELLENCE FIGURE 3: SP304 CONTROL LOGIC CONFIGURATION SELECTION SELECT A: SELECT B: NON- LOOPBACK (LB = 1) RIA2 RIA1 TOA1 TOA2 RIB2 RIB1 TOB1 TOB2 LOGIC VALUE 0 0 ROA2 ROA1 TIA1 TIA2 ROB2 ROB1 TIB1 TIB2 RIA2 RIA1 TOA1 TOA2 LOGIC VALUE 0 1 ROA2 ROA1 TIA1 TIA2 RIA2 RIA1 TOA1 TOA2 ROA1 RIA2 RIA1 TOA1 TOA2 ROA1 LOGIC VALUE 1 0 LOGIC VALUE 1 1 TIA1 TIA1 RIB2 RIB1 TOB1 TOB2 RIB2 ROB1 RIB1 TOB1 TOB2 ROB2 ROB1 TIB1 TIB2 RIB2 RIB1 TOB1 TOB2 ROB1 TIB1 TIB1 LOOPBACK (LB=0) RIA2 RIA1 TOA*1 TOA*2 RIB2 RIB1 TOB1 TOB2 ROA2 ROA1 TIA1 TIA2 ROB2 ROB1 TIB1 TIB2 RIA2 RIA1 TOA*1 TOA*2 ROA2 RIA2 ROA1 RIA1 TIA1 TIA2 RIB2 ROB1 RIB1 TOB1 TOB2 TOA*1 TOA*2 ROA1 RIA2 RIA1 ROA1 TOA*1 TIA1 TOA* 2 TIA1 RIB2 RIB1 TOB*1 TOB*2 ROB2 ROB1 TIB1 TIB2 RIB2 RIB1 TOB*1 TOB*2 ROB1 TIB1 TIB1 RS-232 DRIVER * Tri-state Output RS-232 RECEIVER RS-422 RECEIVER RS-422 DRIVER Corporation 83 SIGNAL PROCESSING EXCELLENCE FIGURE 4: SP304 CONFIGURATIONS Four-Channel Duplex RS-232 Four independent channels of RS-232 line driver and four channels of RS-232 receiver. Two-Channel Duplex RS-232 & One-Channel Duplex RS-422 Two RS-232 line drivers and receivers, and a single RS-422 line driver and receiver. TIA1 TOA1 TIA2 TOA2 TIA1 TOA1 TIB1 TOB1 TIA2 TOA2 TIB2 TOB2 RS-232 LINE DRIVERS RS-232 RECEIVERS RS-232 LINE DRIVERS RS-232 RECEIVERS ROA1 RIA2 ROA2 RIB1 ROB1 RIB2 ROB2 SELECT A = 0 SELECT B = 0 LB = 1 RIA1 RIA1 ROA1 RIA2 ROA2 TIB1 TOB1 TOB2 RS-422 LINE DRIVER RS-422 RECEIVER ROB1 RIB1 RIB2 SELECT A = 0 SELECT B = 1 LB = 1 84 Corporation SIGNAL PROCESSING EXCELLENCE FIGURE 5: SP304 CONFIGURATIONS Two-Channel Duplex RS-232 & One-Channel Duplex RS-422 Opposite Drivers Two RS-232 line drivers and receivers, and a single RS-422 line driver and receiver. At first glance, this is the same configuration as that in Figure 4. Note however that functions are activated on the opposite channels. Two-Channel Duplex RS-422 Two RS-422 line drivers and two RS-422 receivers. TIB1 TOB1 TIA1 TOA1 TOA2 TOB1 TOB2 TIB2 TOB2 TIB1 RS-232 LINE DRIVERS RS-232 RECEIVER ROB1 RIB1 RS-422 LINE DRIVERS RS-422 RECEIVERS ROA1 RIA1 RIA2 RIB1 ROB1 RIB2 ROB2 RIB2 TIA1 TOA1 TOA2 SELECT A = 1 SELECT B = 1 LB = 1 RS-422 LINE DRIVER RS-422 RECEIVER ROA1 RIA1 RIA2 SELECT A = 1 SELECT B = 0 LB = 1 Corporation 85 SIGNAL PROCESSING EXCELLENCE LOOPBACK The SP304 has a function called loopback, which is essentially a chip self-test. However, by connecting system test loops with the inputs and outputs of the SP304, a system-level diagnostic can be run on power-up or on command. The test loops can be enabled and disabled allowing both system test and operation with the same components. A maximum data rate for loopback of 3kbps is recommended. Loopback is a pin-programmable function, activated by a logic low on the LB pin (19). As shown in these figures, the loopback function internally con- SP304 CONFIGURATIONS IN LOOPBACK MODE Two -Channel Full Duplex RS-232 TIA1 TOA1 One-Channel Full Duplex RS-232 & One-Channel Full Duplex RS-422 RS-232 LINE DRIVER RS-232 RECEIVER ROA1 RIA1 TIB1 TOB2 TOB1 TIA2 TOA2 RS-422 LINE DRIVER RS-232 LINE DRIVER RS-232 RECEIVER ROA2 RIA2 RS-422 RECEIVER ROB1 RIB1 RIB2 TIB1 TOB1 TIA1 TOA1 RS-232 LINE DRIVER RS-232 RECEIVER ROB1 RIB1 RS-232 LINE DRIVER RS-232 RECEIVER ROA1 RIA1 TIB2 TOB2 TIA2 TOA2 RS-232 LINE DRIVER RS-232 RECEIVER ROB2 RIB2 RS-232 LINE DRIVER RS-232 RECEIVER ROA2 RIA2 SELECT A = 0 SELECT B = 0 LB = 0 (ACTIVE) SELECT A = 0 SELECT B = 1 LB = 0 (ACTIVE) 86 Corporation SIGNAL PROCESSING EXCELLENCE nects the driver outputs to the corresponding receiver inputs, and switches the output pin to a high impedance from VEE to ground. Receiver outputs are left active for signal verification. During loopback, the receiver inputs are tied to ground via a 5k pulldown resistor. The receiver inputs can accept the full 15V swings with no interference to the loopback function. SP304 CONFIGURATIONS IN LOOPBACK MODE One-Channel Full Duplex RS-232 & One-Channel Full Duplex RS-422 Opposite Drivers Two-Channel Full Duplex RS-422 TIB2 TOB2 TOB2 TIB1 TIB1 TOB1 TOB1 RS-232 LINE DRIVERS RS-232 RECEIVERS ROB2 RIB2 RS-422 LINE DRIVERS RS-422 RECEIVERS ROB1 RIB1 RIB2 ROB1 RIB1 TIA1 TIA1 TOA2 TOA1 TOA2 TOA1 RS-422 LINE DRIVERS RS-422 RECEIVERS RS-422 LINE DRIVER RS-422 RECEIVER ROA1 RIA1 RIA2 ROA1 RIA1 RIA2 SELECT A = 1 SELECT B = 1 LB = 0 (ACTIVE) SELECT A = 1 SELECT B = 0 LB = 0 (ACTIVE) Corporation 87 SIGNAL PROCESSING EXCELLENCE ORDERING INFORMATION Max # of Duplex Channels Model RS-232 RS-422 Temperature Package SP304CS .................. 4 ...................... 2 .................................... 0C to 70C ........................ 24-pin Single-Width Plastic DIP SP304CT .................. 4 ...................... 2 .................................... 0C to 70C ....................................................... 28-pin SOIC SP304ES .................. 4 ...................... 2 .................................. -40C to 85C ....................... 24-pin Single-Width Plastic DIP SP304ET .................. 4 ...................... 2 .................................. -40C to 85C ...................................................... 28-pin SOIC 88 Corporation SIGNAL PROCESSING EXCELLENCE |
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