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1 sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation sp334 programmable rs-232/rs-485 transceiver n +5v only operation n software programmable rs-232 or rs- 485 selection n three rs-232 drivers and five receivers in rs-232 mode n two rs-485 full-duplex transceivers in rs-485 mode n full differential driver tri-state (hi-z) control n receiver output tri-state control description the sp334 is a programmable rs-232 and/or rs-485 transceiver ic. the sp334 contains three drivers and five receivers when selected in rs-232 mode; and two drivers and two receivers when selected in rs-485 mode. 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 rs-485 drivers can be disabled (high-z output) by the txen enable pin. the rs-232 and rs-485 receiver outputs can be disabled by the rxen enable pin. ti3 txen(n/c) tx4(n/c) tx3 vcc tx1 tx2 gnd c1+ v+ c2+ c1C c2C vC ti2 ti1 rxen rs232/rs485 ri5 rx5 rx4 rx3 rx2 rx1 ri4 ri3 ri2 ri1 28 27 26 25 24 23 22 21 20 19 18 17 16 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 sp334 (in rs-232 mode) ? now available in lead free
sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation 2 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. v cc ...........................................................................+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 ? ja ....................................................40 c/w 28-pin plastic soic ? ja ....................................................40 c/w specifications typically 25 c @ vcc = +5v unless otherwise noted. min. typ. max. units conditions logic inputs v il 0.8 volts v ih 2.0 volts logic outputs v ol 0.4 volts i out = -3.2ma v oh 2.4 volts i out = 1.0ma output tri-state leakage 10 m a 0.4v v out +2.4v rs-232 driver dc characteristics high level output +5.0 +15 volts r l =3k w , v in =0.8v low level output e15.0 e5.0 volts r l =3k w , v in =2.0v open circuit voltage e15 +15 volts short circuit current 100 ma v out = 0v power off impedance 300 w v cc = 0v, v out = 2.0v ac characteristics slew rate 30 v/ m sr l =3k w , c l = 50pf v cc = +5.0v, t a @ +25 c transition time 1.56 m sr l =3k w , c l =2500pf ; between 3v, t a @ +25 c maximum data rate 120 235 kbps r l =3k w , c l =2500pf propagation delay t phl 28 m s measured from 1.5v of v in t plh 28 m s to 50% of v out ; r l =3k w rs-232 receiver dc characteristics high threshold 1.7 3.0 volts low threshold 0.8 1.2 volts receiver open circuit bias +2.0 volts input impedance 3 5 7 k w v in = +15v to e15v ac characteristics maximum data rate 120 235 kbps propagation delay t phl 0.25 1 m s measured from 50% of v in t plh 0.25 1 m s to 1.5v of v out . rs-485 driver dc characteristics open circuit voltage 6.0 volts differential output 1.5 5.0 volts r l =54 w , c l =50pf
3 sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation specifications typically 25 c @ vcc = +5v unless otherwise noted. min. typ. max. units conditions rs-485 driver balance 0.2 volts |v t | - |v t | common-mode output 3.0 volts output current 28.0 ma r l =54 w short circuit current 250 ma terminated in e7v to +10v ac characteristics maximum data rate 10 mbps r l =54 w output transition time 30 ns rise/fall time, 10%e90% propagation delay see figures 3a & 5 t phl 80 120 ns r diff =54 w , c l1 =c l2 =100pf t plh 80 120 ns r diff =54 w , c l1 =c l2 =100pf driver output skew 5 20 ns per figure 5, t skew = |t dplh - t dphl | rs-485 receiver dc characteristics inputs common mode range e7.0 +12.0 volts receiver sensitivity 0.2 volts e7v v cm +12v input impedance 12 15 k w e7v v cm +12v ac characteristics maximum data rate 10 mbps propagation delay see figures 3a & 7 t phl 130 200 ns r diff =54 w , c l1 =c l2 =100pf t plh 130 200 ns r diff =54 w , c l1 =c l2 =100pf differential receiver skew 10 20 ns t skew = | t plh e t phl |; r diff =54 w , c l1 =c l2 =100pf, see figure 8 enable timing rs-485 driver enable time see figures 4 & 6 enable to low 100 150 ns c l =15pf, s 1 closed enable to high 100 150 ns c l =15pf, s 2 closed disable time see figures 4 & 6 disable from low 100 120 ns c l =15pf, s 1 closed disable from high 100 120 ns c l =15pf, s 2 closed rs-485 receiver enable time see figures 2 & 8 enable to low 100 150 ns c l =15pf, s 1 closed enable to high 100 150 ns c l =15pf, s 2 closed disable time see figures 2 & 8 disable from low 100 120 ns c l =15pf, s 1 closed disable from high 100 120 ns c l =15pf, s 2 closed power requirements supply voltage v cc +4.75 +5.25 volts supply current i cc no load (t x disabled) 12 20 ma txen = 0v no load (rs-232 mode) 20 50 ma rs232/rs485 = 0v no load (rs-485 mode) 15 50 ma rs232/rs485 = +5v environmental operating temperature commercial (..c..) 0 +70 c industrial (..e..) e40 +85 c storage temperature e65 +150 c
sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation 4 figure 3a. driver/receiver timing test circuit figure 4. driver timing test load #2 circuit figure 1. driver dc test load circuit figure 2. receiver timing test load circuit c l1 15pf ro a b a b di c l2 r l a b r r v od v oc 500 w c l output under test s 1 s 2 v cc 1k w 1k w c rl receiver output s 1 s 2 test point v cc test circuits receiver input graph +1.0ma ?.6ma +12v +6v ?v ?v 1 unit load maximum input current versus voltage rs-485 receiver
5 sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation figure 6. driver enable and disable times figure 7. receiver propagation delays v oh v ol receiver out 1.5v 1.5v t phl f = 1mhz; t r 10ns; t f 10ns output v 0d2 + v 0d2 e a e b 0v 0v t plh input figure 5. driver propagation delays switching waveforms +3v 0v t x en 5v v ol a, b 0v 1.5v 1.5v t zl t zh f = 1mhz; t r 10ns; t f 10ns v oh a, b 2.3v 2.3v t lz t hz 0.5v 0.5v output normally low output normally high +3v 0v driver input a b driver output v o + differential output v a e v b 0v v o e 1.5v 1.5v t plh t f t r f 3 1mhz; t r 10ns; t f 10ns v o 1/2v o 1/2v o t phl t skew = |t dplh - t dphl | t dplh t dphl
sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation 6 figure 8. receiver enable and disable times +3v 0v 5v 0v 1.5v 1.5v t zl t zh f = 1mhz; t r 10ns; t f 10ns receiver out 1.5v 1.5v t lz t hz 0.5v 0.5v output normally low output normally high v il v ih receiver out r x en t skew = |t phl - t plh | figure 9. typical rs-232 driver output figure 10. typical rs-485 driver output ttl input driver output
7 sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation figure 12. typical operating circuit figure 11. sp334 pinout 25 12 14 +5v gnd ttl/cmos ttl/cmos ttl/cmos 0.1 m f 0.1 m f vcc v+ ve ttl/cmos ttl/cmos t1 t2 t3 r1 tx1 tx2 tx3 ri1 ti1 ti2 ti3 rx1 rx5 rx4 rx3 rx2 ri5 ri4 ri3 ri2 19 15 4 5 6 7 8 10 0.1 m f 0.1 m f c1+ c1- c2+ c2- 9 11 13 23 22 21 20 16 rs232/rs485 27 28 1 400k w vcc 400k w vcc 400k w vcc rs-232 0v ttl/cmos ttl/cmos ttl/cmos 17 18 rs-232 rs-232 rs-232 rs-232 24 5k w 5k w 5k w 5k w sp334 r2 r3 5k w r4 r5 rs-232 rs-232 rs-232 rxen ttl/cmos 26 3 n/c n/c 2 ttl/cmos ttl/cmos ttl/cmos 0.1 m f 0.1 m f c1+ c1- c2+ c2- txen 2 +5v vcc 5 gnd 8 9 11 12 13 19 27 1 r1 rs-485 rs-485 rs-485 ttl/cmos 0.1 m f 0.1 m f v+ ve +5v rs-485 rs-485 rs-485 4 6 7 10 14 16 15 26 25 ri2 ri1 tx3 tx4 tx1 tx2 ti1 ti3 rx1 ttl/cmos 21 17 18 ri4 ri3 rx3 15k w 15k w 400k w vcc 400k w vcc rxen rs-485 rs-485 sp334 3 rs232/rs485 15k w 15k w r3 t1 t3 ttl/cmos ti3 txen(n/c) tx4(n/c) tx3 vcc tx1 tx2 gnd c1+ v+ c2+ c1e c2e ve ti2 ti1 rxen rs232/rs485 ri5 rx5 rx4 rx3 rx2 rx1 ri4 ri3 ri2 ri1 28 27 26 25 24 23 22 21 20 19 18 17 16 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 sp334 (in rs-232 mode)
sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation 8 theory of operation the sp334 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. chargeCpump the charge pump is a sipex Cpatented design (u.s. 5,306,954) and uses a unique approach compared to older lessCefficient designs. the charge pump still requires four external capacitors, but uses a fourCphase voltage shifting technique to attain symmetrical 10v power supplies. figure 17(a) shows the waveform found on the positive side of capcitor c2, and figure 17(b) shows the negative side of capcitor c2. there is a freeCrunning oscillator that controls the four phases of the voltage shifting. a description of each phase follows. phase 1 v ss charge storage during this phase of the clock cycle, the positive side of capacitors c 1 and c 2 are initially charged to +5v. c l + is then switched to ground and charge on c 1 C is transferred to c 2 C . since c 2 + is connected to +5v, the voltage potential across capacitor c 2 is now 10v. phase 2 v ss transfer phase two of the clock connects the negative terminal of c 2 to the v ss storage capacitor and the positive terminal of c 2 to ground, and transfers the generated Cl0v to c 3 . simultaneously, the positive side of capaci- tor c 1 is switched to +5v and the negative side is connected to ground. phase 3 v dd charge storage the third phase of the clock is identical to the first phase the charge transferred in c 1 produces C5v in the negative terminal of c 1 , which is applied to the negative side of capacitor c 2 . since c 2 + is at +5v, the voltage potential across c 2 is l0v. phase 4 v dd transfer the fourth phase of the clock connects the negative terminal of c 2 to ground and transfers the generated l0v across c 2 to c 4 , the v dd storage capacitor. again, simultaneously with this, the positive side of figure 13. charge pump phase 1. figure 14a. charge pump phase 2. capacitor c 1 is switched to +5v and the negative side is connected to ground, and the cycle begins again. since both v+ and v C are separately generated from v cc in a noCload condition, v+ and v C will be symmetrical. older charge pump approaches that generate v C from v+ will show a decrease in the magnitude of v C compared to v+ due to the inherent inefficiencies in the design. the clock rate for the charge pump typically operates at 15khz. the external capacitors must be a minimum of 0.1 m f with a 16v breakdown rating. external power supplies for applications that do not require +5v only, external supplies can be applied at the v+ and v C pins. the value of the external supply volt- ages must be no greater than l0v. the current drain for the 10v supplies is used for rs232. for the rs-232 driver the current requirement will be 3.5ma per driver. the external power supplies should provide a power supply se- quence of :+l0v, then +5v, followed by Cl0v. drivers the sp334 has three independent rs-232 single- ended drivers and two differential rs-485 drivers. control for the mode selection is done by the rs-232/rs-485 select pin. the drivers are pre-arranged such that for each mode of v cc = +5v ?v ?v +5v v ss storage capacitor v dd storage capacitor c 1 c 2 c 3 c 4 + + ++ v cc = +5v ?0v v ss storage capacitor v dd storage capacitor c 1 c 2 c 3 c 4 + + ++
9 sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation figure 15. charge pump phase 3. figure 16. charge pump phase 4. 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, pullCup resistors to +5v or pullCdown resistors to ground are suggested. since the driver inputs are both ttl or cmos compatible, any value resistor less than 100k w will suffice. when in rs-232 mode, the single-ended rs- 232 drivers produce compliant rs-232e and itu v.28 signals. each of the three drivers output single-ended bipolar signals in excess of v cc = +5v ?v +5v ?v v ss storage capacitor v dd storage capacitor c 1 c 2 c 3 c 4 + + ++ v cc = +5v +10v v ss storage capacitor v dd storage capacitor c 1 c 2 c 3 c 4 + + ++ figure 17. charge pump waveforms 5v with a full load of 3k w and 2500pf applied as specified. these drivers can also operate at least 120kbps. when programmed to rs-485 mode, the differential rs-485 drivers produce complaint rs-485 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 54 w between the driver's two output pins. the signal levels and drive capability of the rs-485 drivers allow the drivers to also comply with rs-422 levels. the transmission rate for the differential drivers is 10mbps. receivers the sp334 has five 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 by the same select pin as 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 without causing oscillation. to ensure a desired state of the receiver output, a pullCup resistor of 100k w to +5v should be connected to the inverting input for a logic low, or the nonCinverting input for a logic high. for single-ended receivers, a pullCdown resistor to ground of 5k w is internally connected, which will ensure a logic high output. +10v a) c 2 + gnd gnd -10v b) c 2 -
sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation 10 outputs. the drivers can only be tri-stated in rs-485 mode. the drivers are always active in rs-232 mode. the receiver outputs can also be tri-stated by use of the rxen pin. a logic low will enable the receiver outputs and a logic high will tri-state the outputs. the receiver tri-state capability is offered for both rs-232 and rs-485 modes. the input impedance if the receivers during tri-state is at least 12k w . applications the sp334 allows the user flexibility in having a rs-232 or rs-485 serial port without using two different discrete active ics. figure 18 shows a connection to a standard db-9 rs-232 connector. in rs-485 mode, the sp334 is a full duplex transceiver, however, a half duplex configuration can be made by connecting the driver outputs to the receiver inputs. 25 12 14 +5v gnd cts txd rts 0.1 m f 0.1 m f vcc v+ ve dtr rxd t1 t2 t3 r1 tx1 tx2 tx3 ri1 ti1 ti2 ti3 rx1 rx5 rx4 rx3 rx2 ri5 ri4 ri3 ri2 19 15 4 5 6 7 8 10 0.1 m f 0.1 m f c1+ c1- c2+ c2- 9 11 13 23 22 21 20 16 rs232/rs485 27 28 1 400k w vcc 400k w vcc 400k w vcc 0v dsr dcd ri 17 18 24 5k w 5k w 5k w 5k w sp334 r2 r3 5k w r4 r5 rxen 26 1 9 5 6 txd dtr rts rxd cts dsr dcd ri sg figure 18. sp334 configuration to a db-9 serial port the rs-232 receiver has a singleCended 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 15k w and a differential threshold of 200mv. since the characteristics of an rs- 422 receiver are actually subsets of rs485, the receivers for rs-422 requirements are identical to the rs-485 receivers. all of the differential receivers can receive data up to 10mbps. enable pins the sp334 drivers can be enabled by use of the txen pin. a logic high will enable the driver outputs and a logic low will tri-state the
11 sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation d eh package: 28-pin plastic small outline (soic) dimensions (inches) minimum/maximum (mm) a a1 l b e a a1 b d e e h l 28epin 0.093/0.104 (2.352/2.649) 0.004/0.012 (0.102/0.300) 0.013/0.020 (0.330/0.508) 0.698/0.706 (17.73/17.93) 0.291/0.299 (7.402/7.600) 0.050 bsc (1.270 bsc) 0.394/0.419 (10.00/10.64) 0.016/0.050 (0.406/1.270) 0 /8 (0 /8 )
sp334ds/10 programmable rs-232/rs-485 transceiver ? copyright 2000 sipex corporation 12 ordering information model temperature range package types sp334ct ........................................................................... 0 c to +70 c .................................................................................. 28-pin plastic soic sp334et ........................................................................ -40 c to +85 c .................................................................................. 28-pin plastic soic sipex corporation reserves the right to make changes to any products described herein. sipex does not assume any liability aris ing 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. now available in lead free. to order add "-l' to the part number. example: sp488a = normal, sp488a-l = lead free

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