® SP331 Programmable RS-232/RS-485 Transceiver ■ +5V Only Operation ■ Software Programmable RS-232 or RS-485 Selection ■ Four RS-232 Transceivers in RS-232 Mode ■ Two RS-485 Full-Duplex Transceivers in RS-485 Mode ■ Two RS-232 Transceivers and One RS-485 Transceiver in Dual Mode ■ Self-Testing Loopback Mode ■ Full Driver Tri-State (Hi-Z) Control ■ Ideal for RS-232 to RS-485 conversion DESCRIPTION… The SP331 is a programmable RS-232 and/or RS-485 transceiver IC. The SP331 contains four drivers and four receivers when selected in RS-232 mode; and two drivers and two receivers when selected in RS-485 mode. The SP331 also contains a dual mode which has two RS-232 drivers/receivers plus one differential RS-485 driver/receiver. The RS-232 transceivers can typically operate at 230kbps while adhering to the RS-232 specifications. The RS-485 transceivers can operate up to 10Mbps while adhering to the RS-485 specifications. The SP331 includes a self-test loopback mode where the driver outputs are internally configured to the receiver inputs. This allows for easy diagnostic serial port testing without using an external loopback plug. The RS-232 and RS-485 drivers can be disabled (High-Z output) by controlling a set of four select pins. SP331DS/13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 SP331 TI4 SEL_B TX4 TX3 VCC TX1 TX2 GND C1+ V+ (VDD) C2+ C1– C2– V– (VSS) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 TI3 TI2 TI1 SEL_C SEL_A SEL_D RX4 RX3 RX2 RX1 RI4 RI3 RI2 RI1 SP331 RS-232/RS-485 Serial Transceiver 1 © Copyright 2000 Sipex Corporation ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. VCC...........................................................................+7V Storage Temperature..........................-65˚C to +150˚C Power Dissipation 28-pin Plastic DIP...........................1000mW 28-pin Plastic SOIC.......................1000mW Package Derating: 28-pin Plastic DIP øJA....................................................40 °C/W 28-pin Plastic SOIC øJA....................................................40 °C/W SPECIFICATIONS Typically 25°C @ Vcc = +5V unless otherwise noted. MIN. LOGIC INPUTS VIL VIH LOGIC OUTPUTS VOL VOH RS-232 DRIVER DC Characteristics HIGH Level Output LOW Level Output Open Circuit Voltage Short Circuit Current Power Off Impedance TYP. SP331DS/13 0.4 Volts Volts +15 –5.0 +15 ±100 Volts Volts Volts mA Ω 30 V/µs 1.5 µs 300 Transition Time AC Characteristics Maximum Data Rate Propagation Delay tPHL tPLH RS-485 DRIVER DC Characteristics Open Circuit Voltage Differential Output Volts Volts 2.4 +5.0 –15.0 –15 120 235 2 2 8 8 1.7 1.2 3.0 0.8 3 5 120 235 +2.0 7 CONDITIONS IOUT= -3.2mA IOUT= 1.0mA RL=3kΩ, VIN=0.8V RL=3kΩ, VIN=2.0V VOUT = 0V Vcc = 0V, Vout = ±2.0V kbps RL=3kΩ, CL= 50pF VCC = +5.0V, TA @ +25°C RL=3kΩ, CL=2500pF ; between ±3V, TA @ +25°C RL=3kΩ, CL=2500pF µs µs Measured from 1.5V of VIN to 50% of VOUT; RL=3kΩ Volts Volts Volts kΩ VIN = +15V to –15V kbps 0.25 0.25 1.5 UNITS 0.8 2.0 AC Characteristics Slew Rate Maximum Data Rate Propagation Delay tPHL tPLH RS-232 RECEIVER DC Characteristics HIGH Threshold LOW Threshold Receiver Open Circuit Bias Input Impedance MAX. 1 1 6.0 5.0 µs µs Volts Volts SP331 RS-232/RS-485 Serial Transceiver 2 Measured from 50% of VIN to 1.5V of VOUT. RL=54Ω, CL=50pF © Copyright 2000 Sipex Corporation SPECIFICATIONS Typically 25°C @ Vcc = +5V unless otherwise noted. MIN. RS-485 DRIVER Balance Common-Mode Output Output Current Short Circuit Current AC Characteristics Maximum Data Rate Output Transition Time Propagation Delay tPHL tPLH Driver Output Skew RS-485 RECEIVER DC Characteristics Inputs Common Mode Range Receiver Sensitivity Input Impedance AC Characteristics Maximum Data Rate Propagation Delay tPHL tPLH Differential Receiver Skew ENVIRONMENTAL Operating Temperature Commercial (..C..) Industrial (..E..) Storage Temperature SP331DS/13 MAX. UNITS ±0.2 3.0 ±250 Volts Volts mA mA 30 50 Mbps ns 80 80 10 120 120 20 ns ns ns RL=54Ω Rise/fall time, 10%–90% See Figures 2 & 4 RDIFF=54Ω, CL1=CL2=100pF RDIFF=54Ω, CL1=CL2=100pF per Figure 4, tSKEW = | tDPLH - tDPHL| Volts Volts kΩ –7V ≤ VCM ≤ +12V –7V ≤ VCM ≤ +12V 28.0 10 –7.0 12 ±0.2 15 +12.0 ±0.3 10 ENABLE TIMING RS-485 Driver Enable Time Enable to Low Enable to High Disable Time Disable From Low Disable From High POWER REQUIREMENTS Supply Voltage VCC Supply Current ICC No Load (Tx Disabled) No Load (RS-232 Mode) No Load (RS-485 Mode) TYP. |VT| - |VT| RL=54Ω Terminated in –7V to +10V Mbps 130 130 10 200 200 20 ns ns ns 90 90 150 150 ns ns 80 80 120 120 ns ns +4.75 +5.25 10 15 7 0 –40 –65 CONDITIONS See Figures 3 & 5 CL=15pF, S1 Closed CL=15pF, S2 Closed See Figures 3 & 5 CL=15pF, S1 Closed CL=15pF, S2 Closed Volts 15 30 20 mA mA mA +70 +85 +150 °C °C °C SP331 RS-232/RS-485 Serial Transceiver 3 See Figures 2 & 6 RDIFF=54Ω, CL1=CL2=100pF RDIFF=54Ω, CL1=CL2=100pF tSKEW = | tPLH – tPHL |; RDIFF=54Ω, CL1=CL2=100pF SEL_A ➨ SEL_D = "0001" SEL_A ➨ SEL_D = "0000" SEL_A ➨ SEL_D = "1100" © Copyright 2000 Sipex Corporation RECEIVER INPUT GRAPH RS-485 RECEIVER +1.0mA –7V –3V +6V +12V 1 Unit Load Maximum Input Current versus Voltage –0.6mA TEST CIRCUITS A CL1 R DI VOD A RL RO B R A B CL2 VOC 15pF B Figure 1. Driver DC Test Load Circuit Output Under Test 500Ω Figure 2. Driver/Receiver Timing Test Circuit S1 VCC CL S2 Figure 3. Driver Timing Test Load #2 Circuit SP331DS/13 SP331 RS-232/RS-485 Serial Transceiver 4 © Copyright 2000 Sipex Corporation SWITCHING WAVEFORMS f ≥ 1MHz; tR ≤ 10ns; tF ≤ 10ns +3V 1.5V DRIVER INPUT 0V B DRIVER OUTPUT 1.5V tPLH tPHL VO 1/2VO 1/2VO A tDPLH DIFFERENTIAL VO+ OUTPUT 0V VA – VB VO– tDPHL tF tR tSKEW = |tDPLH - tDPHL| Figure 4. Driver Propagation Delays f = 1MHz; tR < 10ns; tF < 10ns +3V 1.5V DE 0V 1.5V tZL tLZ 5V 2.3V A, B VOL VOH A, B 2.3V 0V Output normally LOW 0.5V Output normally HIGH 0.5V tZH tHZ Figure 5. Driver Enable and Disable Times f = 1MHz; tR ≤ 10ns; tF ≤ 10ns V0D2+ A–B 0V VOH RECEIVER OUT VOL 0V INPUT V0D2– 1.5V 1.5V OUTPUT tPHL tPLH Figure 6. Receiver Propagation Delays SP331DS/13 SP331 RS-232/RS-485 Serial Transceiver 5 © Copyright 2000 Sipex Corporation TTL Input Driver Output Figure 7. Typical RS-232 Driver Output SP331DS/13 Figure 8. Typical RS-485 Driver Output SP331 RS-232/RS-485 Serial Transceiver 6 © Copyright 2000 Sipex Corporation 1 2 3 4 5 6 7 8 9 10 11 12 13 14 SP331 TI4 SEL_B TX4 TX3 VCC TX1 TX2 GND C1+ V+ (VDD) C2+ C1– C2– V– (VSS) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 TI3 TI2 TI1 SEL_C SEL_A SEL_D RX4 RX3 RX2 RX1 RI4 RI3 RI2 RI1 Figure 9. SP331 Pinout +5V 9 0.1µF 0.1µF 0V 0V C1+ 12 C111 C2+ 13 C224 SEL A 2 SEL B +5V 5 VCC 5 9 SP331 V+ V- 10 0.1µF 0.1µF 14 0.1µF 0.1µF +5V 23 0V SEL D +5V Vcc Vcc TX1 6 T1 TTL/CMOS RS-232 27 TI2 Vcc TX2 7 TTL/CMOS T2 TTL/CMOS 400KΩ TTL/CMOS 28 TI3 TX3 4 T3 RS-232 TTL/CMOS Vcc TTL/CMOS 400KΩ TTL/CMOS 1 TI4 SP331 V- SEL D Vcc TX4 3 T4 TI2 RS-232 28 TI3 1 20 TTL/CMOS TX1 6 Vcc 19 RX1 RI1 15 R1 TTL/CMOS TX3 4 RI2 16 R1 TTL/CMOS RI2 16 RS-232 TTL/CMOS R2 5KΩ TTL/CMOS 21 RX3 RI3 17 R3 22 RX4 8 GND RS-485 RS-485 15KΩ RI1 15 RS-485 15KΩ R3 RS-485 15KΩ RI3 17 5KΩ 20 RX2 RS-485 RS-485 T3 RX2 21 RX3 RS-232 RS-485 TX4 3 RI4 18 TTL/CMOS 0V T1 TI4 19 RX1 23 TX2 7 26 TI1 27 14 0.1µF 400KΩ RS-232 0.1µF V+ 400KΩ 26 TI1 400KΩ TTL/CMOS 10 12 C111 C2+ 13 C224 SEL A 2 SEL B 400KΩ TTL/CMOS VCC C1+ RS-485 15KΩ SEL C 25 0V RS-232 5KΩ TTL/CMOS 22 RX4 RI4 18 R4 RS-232 5KΩ 8 GND SEL C 25 0V Figure 10. Typical Operating Circuit SP331DS/13 SP331 RS-232/RS-485 Serial Transceiver 7 © Copyright 2000 Sipex Corporation FUNCTION TABLE FOR SELECT PINS A B C D MODE 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 RS-232 RS-232 RS-232 RS-232 FUNCTION 0 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 RS-232/RS-485 RS-232/RS-485 RS-232/RS-485 RS-232/RS-485 T1 and T2 active RS-232; T3 tri-state RS-485 T1 and T2 tri-state RS-232; T3 active RS-485 T1 and T2 active RS-232; T3 tri-state RS-485 RS-232 (2ch) / RS-485 (1ch) Loopback 1 1 1 1 0 0 0 0 0 0 1 1 0 1 0 1 RS-485/RS-232 RS-485/RS-232 RS-485/RS-232 RS-485/RS-232 T1 active RS-485; T2 and T3 active RS-232 T1 tr-state RS-485; T3 active RS-232; T4 active RS232 All RS-485 and RS-232 drivers tri-state RS-485 (1ch) / RS-232 (2ch) Loopback 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0 1 RS-485 RS-485 RS-485 RS-485 All four RS-232 drivers active All four RS-232 drivers tri-state All four RS-232 drivers tri-state RS-232 (4ch) Loopback T1 and T3 active RS-485 T1 tri-state RS-485; T3 active RS-485 T1 active RS-485; T3 tri-state RS-485 RS-485 (2ch) Loopback Table 1. Mode Function Table. (Refer to Control Logic Confirmations for Block Diagrams) THEORY OF OPERATION The SP331 is made up of four separate circuit blocks — the charge pump, drivers, receivers, and decoder. Each of these circuit blocks is described in more detail below. +5V, the voltage potential across capacitor C2 is now 10V. Phase 2 — VSS transfer — Phase two of the clock connects the negative terminal of C2 to the VSS storage capacitor and the positive terminal of C2 to ground, and transfers the generated –l0V to C3. Simultaneously, the positive side of capacitor C 1 is switched to +5V and the negative side is connected to ground. Charge–Pump The charge pump is a Sipex–patented design (U.S. 5,306,954) and uses a unique approach compared to older less efficient designs. The charge pump still requires four external capacitors, but uses a four–phase voltage shifting technique to attain symmetrical 10V power supplies. Figure 15(a) shows the waveform found on the positive side of capcitor C2, and Figure 15(b) shows the negative side of capcitor C2. There is a free–running oscillator that controls the four phases of the voltage shifting. A description of each phase follows. Phase 3 — VDD charge storage — The third phase of the clock is identical to the first phase — the charge transferred in C1 produces –5V in the negative terminal of C1, which is applied to the negative side of capacitor C2. Since C2+ is at +5V, the voltage potential across C2 is l0V. Phase 1 — VSS charge storage —During this phase of the clock cycle, the positive side of capacitors C1 and C2 are initially charged to +5V. Cl+ is then switched to ground and charge on C1– is transferred to C2–. Since C2+ is connected to SP331DS/13 Phase 4 — VDD transfer — The fourth phase of the clock connects the negative terminal of C2 to ground and transfers the generated l0V across C2 to C4, the VDD storage capacitor. Again, SP331 RS-232/RS-485 Serial Transceiver 8 © Copyright 2000 Sipex Corporation simultaneously with this, the positive side of capacitor C1 is switched to +5V and the negative side is connected to ground, and the cycle begins again. VCC = +5V C4 +5V + C1 – C2 –5V + – – + + – VDD Storage Capacitor Since both V+ and V– are separately generated from VCC in a no–load condition, V+ and V– will be symmetrical. Older charge pump approaches that generate V– from V+ will show a decrease in the magnitude of V– compared to V+ due to the inherent inefficiencies in the design. VSS Storage Capacitor C3 –5V Figure 11. Charge Pump Phase 1. VCC = +5V C4 + + C1 C2 – – + – + – The clock rate for the charge pump typically operates at 15kHz. The external capacitors must be 0.1µF with a 16V breakdown rating. VDD Storage Capacitor VSS Storage Capacitor C3 –10V External Power Supplies For applications that do not require +5V only, external supplies can be applied at the V+ and V– pins. The value of the external supply voltages must be no greater than ±l0V. The current drain for the ±10V supplies is used for RS-232. For the RS-232 driver the current requirement will be 3.5mA per driver. The external power supplies should provide a power supply sequence of :+l0V, then +5V, followed by –l0V. Figure 12. Charge Pump Phase 2. VCC = +5V C4 +5V C1 + – C2 –5V + – – + + – VDD Storage Capacitor VSS Storage Capacitor C3 –5V Figure 13. Charge Pump Phase 3. VCC = +5V C4 +10V C1 + – C2 + – – + + – VDD Storage Capacitor VSS Storage Capacitor C3 Figure 14. Charge Pump Phase 4. +10V a) C2+ GND GND b) C2-10V Figure 15. Charge Pump Waveforms SP331DS/13 SP331 RS-232/RS-485 Serial Transceiver 9 © Copyright 2000 Sipex Corporation without causing oscillation. To ensure a desired state of the receiver output, a pull–up resistor of 100kΩ to +5V should be connected to the inverting input for a logic low, or the non–inverting input for a logic high. For single-ended receivers, a pull–down resistor to ground of 5kΩ is internally connected, which will ensure a logic high output. Drivers The SP331 has four independent RS-232 singleended drivers and two differential RS-485 drivers. Control for the mode selection is done via a four–bit control word. The drivers are prearranged such that for each mode of operation the relative position and functionality of the drivers are set up to accommodate the selected interface mode. As the mode of the drivers is changed, the electrical characteristics will change to support the requirements of clock, data, and control line signal levels. Unused driver inputs can be left floating; however, to ensure a desired state with no input signal, pull–up resistors to +5V or pull–down resistors to ground are suggested. Since the driver inputs are both TTL or CMOS compatible, any value resistor less than 100kΩ will suffice. The RS-232 receiver has a single–ended input with a threshold of 0.8V to 2.4V. The RS-232 receiver has an operating voltage range of ±15V and can receive signals up to 120kbps. RS-232 receivers are used in RS-232 mode for all signal types include data, clock, and control lines of the RS-232 serial port. The differential RS-485 receiver has an input impedance of 15kΩ and a differential threshold of ±200mV. Since the characteristics of an RS422 receiver are actually subsets of RS-485, the receivers for RS-422 requirements are identical to the RS-485 receivers. All of the differential receivers can receive data up to 10Mbps. When in RS-232 mode, the single-ended RS232 drivers produce compliant RS-232E and ITU V.28 signals. Each of the four drivers output single-ended bipolar signals in access of ±5V with a full load of 3kΩ and 2500pF applied as specified. These drivers can also operate at least 120kbps. Select Mode Pins Similar to our SP500 family of multiprotocol products, the SP331 has the ability to change the configuration of the drivers and receivers via a 4–bit switch. Referring to Table 1; RS-232 mode, RS-485 mode, or two different combinations of RS-232/RS-485 can be configured using the SEL_A and SEL_B pins. The drivers can be put into tri-state mode by using the SEL_C and SEL_D pins. All receivers remain active during any tri-state condition of the drivers. When programmed to RS-485 mode, the differential RS-485 drivers produce complaint RS485 signals. Each RS-485 driver outputs a unipolar signal on each output pin with a magnitude of at least 1.5V while loaded with a worst case of 54Ω between the driver's two output pins. The signal levels and drive capability of the RS485 drivers allow the drivers to also comply with RS-422 levels. The transmission rate for the differential drivers is 10Mbps. Loopback Mode Loopback is invoked by asserting "xx11" into the select pins. In RS-232/RS-485 or RS-485/ RS-232 loopback mode, the RS-232 driver outputs loop back into the RS-232 receiver inputs and the RS-485 differential driver loops back into the RS-485 receiver. During loopback, the driver outputs and receiver inputs are disconnected from the outside world. The driver outputs are in tri-state and the receiver inputs are disabled. The input impedance of the receivers during loopback is approximately 15kΩ to ground. Receivers The SP331 has four single-ended receivers when programmed for RS-232 mode and two differential receivers when programmed for RS-485 mode. Control for the mode selection is done via a 4– bit control word, as in the drivers. As the operating mode of the receivers is changed, the electrical characteristics will change to support the requirements of the appropriate serial standard. Unused receiver inputs can be left floating SP331DS/13 SP331 RS-232/RS-485 Serial Transceiver 10 © Copyright 2000 Sipex Corporation SP331 CONTROL LOGIC CONFIGURATION (Refer to Table 1) SEL A SEL B SEL C SEL D 0 0 0 0 0 0 0 1 26 TI1 TX1 6 T1 27 TI2 TX2 7 T2 28 TI3 0 0 1 0 0 1 0 0 0 1 0 1 26 TI1 19 RX1 R1 20 RX2 R2 21 RX3 R3 RI1 15 28 TI3 T3 RI2 16 19 RX1 22 RX4 TX4 3 R1 20 RX2 R2 R4 TX2 7 1 1 0 1 TX1 6 26 TI1 T1 TX2 7 RI1 15 19 RX1 R1 TX4 3 RI2 16 RI1 15 19 RX1 R1 RI2 16 RI2 16 21 RX3 RI4 18 T3 TX4 3 T4 R3 RI3 17 R3 TX3 4 28 TI3 1 TI4 1 1 1 0 TX3 4 T3 RI1 15 RI3 17 21 RX3 1 1 0 0 TX1 6 T1 TX3 4 TX4 3 T4 1 0 1 0 TX2 7 T2 28 TI3 1 TI4 1 0 0 1 26 TI1 TX3 4 T3 1 0 0 0 TX1 6 T1 27 TI2 0 1 1 0 RI4 18 RI3 17 RI3 17 21 RX3 22 RX4 R4 R3 RI4 18 RI4 18 SP331 LOOPBACK (Refer to Table 1) SEL A SEL B SEL C SEL D 0 0 1 1 26 TI1 27 TI2 28 TI3 T1 T2 T3 0 1 1 1 TX1 6 TX2 7 26 TI1 19 RX1 20 RX2 21 RX3 T4 R1 R2 R3 28 TI3 TX3 4 T3 SP331DS/13 R4 TX4 3 TX4 3 RI1 15 19 RX1 TX1 6 T1 20 RX2 TX2 7 26 TI1 TX1 6 T1 TX2 7 T3 TX4 3 R1 R2 28 TI3 1 TI4 RI1 15 RI1 15 R1 RI2 16 19 RX1 RI1 15 R1 RI2 16 RI2 16 RI3 17 R3 TX3 4 TX4 3 T4 21 RX3 RI3 17 TX3 4 T3 19 RX1 RI2 16 1 1 1 1 TX2 7 T2 21 RX3 22 RX4 26 TI1 TX3 4 28 TI3 1 TI4 TX1 6 T1 27 TI2 1 0 1 1 RI4 18 RI4 18 R3 21 RX3 22 RX4 R4 SP331 RS-232/RS-485 Serial Transceiver 11 RI3 17 RI4 18 RI3 17 R3 RI4 18 © Copyright 2000 Sipex Corporation PACKAGE: 28-PIN PLASTIC SMALL OUTLINE (SOIC) E H D A Ø e B A1 L DIMENSIONS (Inches) Minimum/Maximum (mm) SP331DS/13 28–PIN A 0.093/0.104 (2.352/2.649) A1 0.004/0.012 (0.102/0.300) B 0.013/0.020 (0.330/0.508) D 0.698/0.706 (17.73/17.93) E 0.291/0.299 (7.402/7.600) e 0.050 BSC (1.270 BSC) H 0.394/0.419 (10.00/10.64) L 0.016/0.050 (0.406/1.270) Ø 0°/8° (0°/8°) SP331 RS-232/RS-485 Serial Transceiver 12 © Copyright 2000 Sipex Corporation ORDERING INFORMATION Model Temperature Range Package Types SP331CT ........................................................................... 0°C to +70°C .................................................................................. 28-pin Plastic SOIC SP331ET ........................................................................ -40°C to +85°C .................................................................................. 28-pin Plastic SOIC Please consult the factory for pricing and availability on a Tape-On-Reel option. Corporation SIGNAL PROCESSING EXCELLENCE Sipex Corporation Headquarters and Sales Office 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: [email protected] Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600 Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others. SP331DS/13 SP331 RS-232/RS-485 Serial Transceiver 13 © Copyright 2000 Sipex Corporation