+3.0V to+5.5v, 1µA, RS-232/RS-485/422 Multiprotocol Transceivers

Transcription

1 9-7; Rev ; 3/ +3.V to+5.5v, µa, RS-3/RS-485/4 General Description The are programmable RS-3/RS-485/4 multiprotocol transceivers. The MAX3/MAX3 are pin programmable as a TX/RX RS-3 interface or a single RS-485/4 transceiver. The MAX3 is configured as a TX/RX RS-3 interface and a single RS-485/4 transceiver simultaneously. All devices incorporate a proprietary low-dropout transmitter output stage and an on-board dual charge pump to allow RS-3 and RS-485/4 compliant performance from a +3V to +5.5V supply. The receivers feature true fail-safe circuitry that guarantees a logichigh receiver output when the receiver inputs are open or shorted. These devices also feature pin-selectable transmitter slew rates for both RS-3 and RS-485/4 modes. Slew-rate limiting minimizes EMI and reduces reflections caused by improperly terminated cables, allowing error-free data transmission up to 5kbps. Disabling slew-rate limiting allows these devices to transmit at data rates up to Mbps in RS-485/4 mode and up to Mbps in RS-3 mode. The feature a µa shutdown mode, and short-circuit limiting and thermal shutdown circuitry to protect against excessive power dissipation. The MAX3/MAX3 offer a flow-through pinout that facilitates board layout. The MAX3/MAX3/ MAX3 are available in tiny SSOP packages and operate over the commercial and extended temperature ranges. Applications Point-of-Sales Equipment Industrial Controls RS-3 to RS-485 Interface Converters Peripherals Networking Ordering Information PART TEMP RANGE PIN-PACKAGE MAX3CAP C to +7 C SSOP MAX3EAP -4 C to +85 C SSOP MAX3CAG C to +7 C 4 SSOP MAX3EAG -4 C to +85 C 4 SSOP MAX3CAI C to +7 C 8 SSOP MAX3EAI -4 C to +85 C 8 SSOP Features Single-Supply Operation from +3V to +5.5V Pin-Programmable as TX/RX RS-3 or Single RS-485/4 (MAX3/MAX3) TX/RX RS-3 and Single RS-485/4 (MAX3) Pin-Programmable RS-3/RS-485 Transmitter Slew Rates Reduce EMI Mbps RS-485 and Mbps RS-3 Data Rates Pin-Programmable Half-Duplex or Full-Duplex RS-485/4 Operation (MAX3/MAX3) RS-485/4 True Fail-Safe Receivers Transmitters and Receivers Protected Against Wiring Faults µa Shutdown Supply Current /8-Unit Load Allows up to 5 Transceivers on the Bus Typical Operating Circuit TX DI/TIN Z(B)/TOUT 3 5 RTS DE/TIN MAX3 Y(A)/TOUT MAX3 5 RX RO/ROUT A/RIN 8 3 CTS ROUT B/RIN 7 4 GND FAST HDPLX SPI 4 9 µp +3V TO +5.5V RS485/RS3 RJ45 DB9 Pin Configurations appear at end of data sheet. Selector Guide appears at end of data sheet. Maxim Integrated Products For price, delivery, and to place orders, please contact Maxim Distribution at , or visit Maxim s website at

2 ABSOLUTE MAXIMUM RATINGS to GND...-.3V to +V V+ to GND...-.3V to +7V V- to GND...3V to -7V V+ - V- (Note )...+3V Input Voltages TIN, TIN, DI, DE485, RE485, TE3, RE3,, FAST, HDPLX, RS485/RS3 to GND V to +V A, B, RIN, RIN to GND...±5V Output Voltages TOUT, TOUT, Y, Z to GND...±3.V ROUT, ROUT, RO to GND...-.3V to ( +.3V) Output Short-Circuit Duration TOUT, TOUT, Y, Z...Continuous ELECTRICAL CHARACTERISTICS Continuous Power Dissipation (T A = +7 C) -Pin SSOP (derate 9.W/ C above +7 C)...78mW 4-Pin SSOP (derate 9.5W/ C above +7 C)...7mW 8-Pin SSOP (derate.8w/ C above +7 C)...84mW Operating Temperature Ranges MAX3_CA_... C to +7 C MAX3_EA_...-4 C to +85 C Storage Temperature Range...-5 C to +5 C Junction Temperature...+5 C Lead Temperature (soldering, s)...+3 C Note : V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 3V. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ( = +3V to +5.5V, C C4 =.µf when tested at +3.3V ±%; C =.47µF and C, C3, C4 =.33µF when tested at +5V±%; T A = T MIN to T MAX, unless otherwise noted. Typical values are at T A = +5 C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC CHARACTERISTICS Standby Current I CC MAX3/MAX3, no load, RS485/ RS3 = GND..5 MAX3/MAX3, no load, RS485/ RS3 = MAX3 No Load 3. Shutdown Current I CC = GND, receiver inputs open or grounded ma µa TRANSMITTER AND LOGIC (DI, TIN, TIN, DE485, RE485, TE3, RE3, FAST, HDPLX,, RS485/RS3) Logic Input Low V IL.8 V = +3.3V. Logic Input High V IH = +5V.4 V Logic Input Leakage Current I INL ±. ± µa Transmitter Logic Hysteresis V HYS.5 V RS-3 AND RS-485/4 RECEIVER (ROUT, ROUT, RO) Receiver Output Voltage Low V OL I OUT =.5mA.4 V Receiver Output Voltage High V OH I OUT = -.5mA -. V Receiver Output Short Circuit Current I OSR < V O < ± ± ma Receiver Output Leakage Current I OZR Receivers disabled ±.5 ± µa

3 ELECTRICAL CHARACTERISTICS (continued) ( = +3V to +5.5V, C C4 =.µf when tested at +3.3V ±%; C =.47µF and C, C3, C4 =.33µF when tested at +5V±%; T A = T MIN to T MAX, unless otherwise noted. Typical values are at T A = +5 C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS RS-3 RECEIVER (RIN, RIN) Input Voltage Range -5 5 V Input Threshold Low Input Threshold High = +3.3V. = +5V.8 =+3.3V. = +5V.4 Input Hysteresis.5 V Input Resistance kω RS-485/4 RECEIVER (NOTE ) Input Resistance R IN -7V < V CM < +V MAX3/ MAX3 MAX3 48 V CM = +V.5 MAX3 V CM = -7V -.5 Input Current I IN ma V CM = +V.5 MAX3/MAX3 V CM = -7V -.75 Input Differential Threshold V TH - -5 mv Input Hysteresis V TH 3 mv RS-3 TRANSMITTER (TOUT, TOUT) Output Voltage Swing Both transmitter outputs loaded with 3kΩ to GND 9 V V kω ±5 ±5.4 V Output Resistance = V+ = V- =, T_OUT = +V 3 M Ω Output Short-Circuit Current T_OUT = GND ±3 ± ma Output Leakage Current RS-485/4 TRANSMITTER (Y, Z) Differential Output Voltage V OD Figure V OUT = ±V MAX3/ ±5 TE3 = GND or = MAX3 GND MAX3 ±5 R = 7Ω (RS-485) R = 5Ω (RS-4).5 µa V Change in Magnitude of Differential Output Voltage for Complementary Output States V OD R = 7Ω or 5Ω, Figure -.. V Common Mode Output Voltage V OC R = 7Ω or 5Ω, Figure 3 V Change in Magnitude of Common Mode Output Voltage for Complementary Output States V OC R = 7Ω or 5Ω, Figure. V 3

4 ELECTRICAL CHARACTERISTICS (continued) ( = +3V to +5.5V, C C4 =.µf when tested at +3.3V ±%; C =.47µF and C, C3, C4 =.33µF when tested at +5V±%; T A = T MIN to T MAX, unless otherwise noted. Typical values are at T A = +5 C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Output Short-Circuit Current I SC V Y or V Z = +V to 7V ±5 ma Output Leakage Current IO V Y or V Z = +V, MAX3/ ±5 DE485 = GND or = MAX3 GND MAX3 ±5 RS-3 TIMING CHARACTERISTICS (FAST = GND, 5kbps, ONE TRANSMITTER SWITCHING) Maximum Data Rate R L = 3kΩ, C L = pf 5 kbps Receiver Propagation Delay R_IN to R_OUT, C L = 5pF.5 µs Receiver Output Enable Time ns Receiver Output Disable Time ns Transmitter Skew t PHL - t PLH ns Receiver Skew t PLH - t PHL 5 ns Transition-Region Slew Rate = +3.3V, T A = +5 C, R L =3kΩ to 7kΩ, measured from +3.V or 3.V to +3.V C L = 5pF to pf C L = 5pF to 5pF RS-3 TIMING CHARACTERISTICS (FAST =, Mbps, ONE TRANSMITTER SWITCHING) Maximum Data Rate = +3V to +4.5V, R L = 3kΩ, C L = 5pF = +4.5V to +5.5V, R L = 3kΩ, C L = pf Receiver Propagation Delay R_IN to R_OUT, C L = 5pF.5 µs Receiver Output Enable Time ns Receiver Output Disable Time ns Transmitter Skew t PHL - t PLH 5 ns Receiver Skew t PLH - t PHL 5 ns Transition-Region Slew Rate RS-485/4 TIMING CHARACTERISTICS (FAST = GND) 5kbps Driver Propagation Delay Driver Rise and Fall Time = +3.3V, T A = +5 C, R L =3kΩ to 7kΩ, C L = 5pF to pf, measured from +3.V or 3.V to +3.V µa V/µs Mbps 4 5 V/µs t DPHL, t DPLH R DIFF = 54Ω, C L = 5pF, Figures 3, ns t DPHL, t DPLH R DIFF = 54Ω, C L = 5pF, Figures 3, ns Driver Propagation Delay Skew t DSKEW R DIFF = 54Ω, C L = 5pF, Figure 3, 5 ns Driver Output Enable Time t DZH, t RZL R DIFF = 54Ω, C L = 5pF, Figures 4, 4 8 ns Driver Output Disable Time t DLZ, t DHZ R DIFF = 54Ω, C L = 5pF, Figure 4, 4 ns Receiver Propagation Delay Receiver Propagation Delay Skew t RPLH, t RPHL C L = 5pF, Figures 7, ns t RSKEW C L = 5pF, Figures 7, 9 ns 4

5 ELECTRICAL CHARACTERISTICS (continued) ( = +3V to +5.5V, C C4 =.µf when tested at +3.3V ±%; C =.47µF and C, C3, C4 =.33µF when tested at +5V±%; T A = T MIN to T MAX, unless otherwise noted. Typical values are at T A = +5 C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Receiver Output Enable Time t RZL, t RZH C L = 5pF, Figures, 8 ns Receiver Output Disable Time t RLZ, t RHZ C L = 5pF, Figures, 8 ns RS-485/RS-4 TIMING CHARACTERISTICS (FAST =, Mbps) Driver Propagation Delay t DPHL, t DPLH R DIFF = 54Ω, C L = 5pF, Figures 3, 5 ns Driver Rise And Fall Times t DR, t DF R DIFF = 54Ω, C L = 5pF, Figures 3, 5 5 ns Driver Propagation Delay Skew t DSKEW R DIFF = 54Ω, C L = 5pF, Figures 3, 5 ns Driver Output Enable Time tdzl R DIFF = 54Ω, C L = 5pF, Figures 4, 4 8 ns Driver Output Disable Time t DLZ, t DHZ R DIFF = 54Ω, C L = 5pF, Figures 4, 4 ns Receiver Propagation Delay t RPLH, t RPHL C L = 5pF, Figures 7, ns Receiver Propagation Delay Skew t RSKEW C L = 5pF, Figures 7, 9 ns Receiver Output Enable Time t RZL, t RZH C L = 5pF, Figures, 8 ns Receiver Output Disable Time t RLZ, t RHZ C L = 5pF, Figures, 8 ns Note : Applies to A, B for MAX3 and MAX3/MAX3 with HDPLX = GND, or Y, Z for MAX3/MAX3 with HDPLX =. Typical Operating Characteristics ( = +3.3V, 5kbps data rate,.µf capacitors, all RS-3 transmitters (RS-3 mode) loaded with 3kΩ to ground, T A = +5 C, unless otherwise noted.) TRANSMITTER OUTPUT VOLTAGE (V) RS-3 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (FAST = GND) MAX3/ TOC TRANSMITTER OUTPUT VOLTAGE (V) RS-3 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (FAST = ) MAX3/ TOC SLEW RATE (V/µs) RS-3 TRANSMITTER SLEW RATE vs. LOAD CAPACITANCE (FAST = GND) MAX3/ TOC LOAD CAPACITANCE (pf) LOAD CAPACITANCE (pf) LOAD CAPACITANCE (pf) 5

6 Typical Operating Characteristics (continued) ( = +3.3V, 5kbps data rate,.µf capacitors, all RS-3 transmitters (RS-3 mode) loaded with 3kΩ to ground, T A = +5 C, unless otherwise noted.) SLEW RATE (V/µs) SHUTDOWN CURRENT (na) RS-3 TRANSMITTER SLEW RATE vs. LOAD CAPACITANCE (FAST = ) 5 5 LOAD CAPACITANCE (pf) SHUTDOWN CURRENT vs. TEMPERATURE TEMPERATURE ( C) MAX3/ TOC4 MAX3/ TOC7 SUPPLY CURRENT (ma) OUTPUT CURRENT (ma) OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE WHEN TRANSMITTING DATA (RS-3 MODE) Mbps 5kbps kbps LOAD CAPACITANCE (pf) RS-485/4 OUTPUT CURRENT vs. DRIVER OUTPUT VOLTAGE 4 8 OUTPUT LOW VOLTAGE (V) MAX3/ TOC5 MAX3/ TOC8 SUPPLY CURRENT (ma) OUTPUT CURRENT (ma) MAX3/MAX3 NO-LOAD SUPPLY CURRENT vs. TEMPERATURE RS-485 MODE RS-3 MODE TEMPERATURE ( C) RS-485/4 OUTPUT CURRENT vs. DRIVER OUTPUT HIGH VOLTAGE OUTPUT HIGH VOLTAGE (V) MAX3/ TOC MAX3/ TOC9 OUTPUT CURRENT (ma). RS-485/4 DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE MAX3/ TOC OUTPUT VOLTAGE (V) RS-485/4 DRIVER DIFFERENTIAL OUTPUT vs. TEMPERATURE R = 5Ω MAX3/ TOC OUTPUT CURRENT (ma) OUTPUT CURRENT vs. RECEIVER OUTPUT LOW VOLTAGE MAX3/ TOC OUTPUT VOLTAGE (V) TEMPERATURE ( C) OUTPUT LOW VOLTAGE (V)

7 Typical Operating Characteristics (continued) ( = +3.3V, 5kbps data rate,.µf capacitors, all RS-3 transmitters (RS-3 mode) loaded with 3kΩ to ground, T A = +5 C, unless otherwise noted.) OUTPUT CURRENT (ma) TIME (ns) CURRENT (µa) OUTPUT CURRENT vs. RECEIVER OUTPUT HIGH VOLTAGE OUTPUT HIGH VOLTAGE (V) RS-485/4 DRIVER PROPAGATION DELAY vs. TEMPERATURE (SLOW) R = 5Ω TEMPERATURE ( C) I-V OUTPUT IMPEDANCE CURVE IN RS-3 SHUTDOWN MODE MAX3/ TOC3 MAX3/ TOC9 MAX3-A PROPAGATION DELAY (ns) RS-485/4 RECEIVER PROPAGATION DELAY vs. TEMPERATURE C L = 5pF 8 4 RISING FALLING TEMPERATURE ( C) RS-485/4 DRIVER PROPAGATION (FAST, Mbps) MAX3/ TOC ns/div RS-485/4 RECEIVER PROPAGATION (FAST, 5Mbps) C L = 5pF MAX3/ TOC MAX3/ TOC DI 5V/div V Y -V Z V/div V Y -V Z V/div RO V/div SUPPLY CURRENT (ma) RS-485/4 DRIVER PROPAGATION DELAY vs.temperature (FAST) R = 5Ω TEMPERATURE ( C) RS-485/4 DRIVER PROPAGATION (SLOW, 5kbps).µs/div MAX3/ TOC RS-485/4 DRIVER DISABLE/ENABLE TO DRIVER OUTPUT R = 5Ω C L = 8pF MAX3/ TOC4 MAX3/ TOC8 DI 5V/div V Y -V Z V/div DE485 V/div V Y - V Z V/div VOLTS (V) 4ns/div ns/div 7

8 PIN MAX3 MAX3 MAX3 NAME FUNCTION Pin Description C+ Positive Terminal of the Positive Flying Capacitor Positive Supply Voltage C- Negative Terminal of the Positive Flying Capacitor GND Ground 5 5 TOUT RS-3 Driver Output 5 Z(B)/TOUT Inverting RS-485/4 Driver Output in Full-Duplex Mode (and Inverting RS-485/4 Receiver Input in Half-Duplex Mode)/RS-3 Driver Output Z Inverting RS-485/4 Driver Output Z(B) Y(A)/TOUT Inverting RS-485/4 Driver Output in Full-Duplex Mode (and Inverting RS-485/4 Receiver Input in Half-Duplex Mode) Noninverting RS-485/4 Driver Output in Full-Duplex Mode (and Noninverting RS-485/4 Receiver Input in Half-Duplex Mode)/RS-3 Driver Output 7 Y Noninverting RS-485/4 Driver Output 7 Y(A) ROUT RS-3 Receiver Output 8 8 TOUT RS-3 Driver Output Noninverting RS-485/4 Driver Output in Full-Duplex Mode (and Noninverting RS-485/4 Receiver Input in Half-Duplex Mode) 8 RO/ROUT RS-485/4 Receiver Output/RS-3 Receiver Output 9 3 Active-Low Shutdown-Control Input. Drive low to shut down transmitters and charge pump. ROUT RS-3 Driver Output 4 FAST Select slew rate limiting for both RS-3 and RS- 485/4. Slew rate limits with a logic-level low. RO RS-485/4 Receiver Output 3 RS485/RS3 Software-Programmable Pin Functionality. Operates as RS-485/4 with a logic-level high; operates as RS-3 with a logic-level low. RE485 4 HDPLX RS-485/4 Receiver Enable. Logic-level low enables RS-485/4 receivers. Software-Programmable Pin Functionality. Operates in full-duplex mode when low; operates in half-duplex mode when high. 8

9 PIN MAX3 MAX3 MAX3 NAME 3 A/RIN 4 B/RIN Pin Description (continued) FUNCTION Noninverting RS-485/4 Receiver Input/RS-3 Receiver Input Inverting RS-485/4 Receiver Input/RS-3 Receiver Input 5 RE3 RS-3 Receiver Enable. Logic-level low enables RS- 3 receivers. 5 7 A Noninverting RS-485/4 Receiver Input 5 9 DE485/TIN RS-485/RS-4 Driver Enable/RS-3 Driver Input TE3 RS-3 Transmitter Output Enable 8 B Inverting RS-485/4 Receiver Input DI/TIN RS-485/RS-4 Driver Input/RS-3 Driver Input 7 9 RIN RS-3 Receiver Input 7 5 V- Negative Charge-Pump Rail 8 RIN RS-3 Receiver Input 8 C- Negative Terminal of the Negative Flying Capacitor C+ Positive Terminal of the Negative Flying Capacitor 4 8 V+ Positive Charge-Pump Rail TIN RS-3 Driver Input DE485 RS-485/RS-4 Driver Enable 3 DI RS-485/RS-4 Driver Input 4 TIN RS-3 Driver Input 9

10 C+ C C BYPASS RS-3 LOGIC GND FAST RS-3 MODE T T R R CHARGE PUMP V+ C+ V- HDPLX RS-485/RS C3 C C4 LOGIC RS-3 MAX3 C+ C RS-485 C+ 9 C- 8 V- 7 C- 3 C BYPASS GND 4 LOGIC OUTPUT R Z Y FAST R Functional Diagrams RS-485 MODE CHARGE PUMP D DE B A V+ RS-485/RS-3 C- C C4 C3 LOGIC RS-485 C HALF/FULL DUPLEX

11 C+ C C BYPASS RS-3 LOGIC C- C- GND RS-3 MODE T T R R CHARGE PUMP V+ C+ C+ C 3 C- C BYPASS 4 GND V- HDPLX C3 C C4 LOGIC RS-3 MAX3 Functional Diagrams (continued) C+ 3 C- V- RS-485 LOGIC OUTPUT R Z Y R RS-485 MODE CHARGE PUMP D DE B A V C3 C4 C LOGIC RS-485 HALF/FULL DUPLEX FAST RS-485/RS-3 3 FAST RS-485/RS-3 3

12 Functional Diagrams (continued) C+ C C BYPASS RS-3 OUTPUT RS-485 RS-3 OUTPUT LOGIC C+ 7 C- V- 5 C- GND R Z Y R RO RE485 MAX3 CHARGE PUMP D R T DE485 T B A V C3 C C4 LOGIC RS-3 RS-485 RECEIVER OUTPUT C L Y Z TEST POINT V OD Figure. RS-485/4 Driver DC Test Load k Figure. RS-485/4 Receiver Enable/Disable Timing Test Load R R Test Circuits S S V OC k 3 4 FAST TE3 5 DE485 3V C L DI Y Z V OD R DIFF C L Figure 3. RS-485/4 Driver Timing Test Circuit

13 OUTPUT UNDER TEST 5Ω C L Figure 4. RS-485/4 Driver Enable/Disable Timing Test Load 3V DE485 Y, Z V OL Y, Z.5V.5V S S.3V OUTPUT NORMALLY LOW.3V t DZL t DLZ OUTPUT NORMALLY HIGH V OL +.5V V OH -.5V DI V DIFF 3V Z Y V O -V O V O.5V / V O T DR % Test Circuits (continued) t DPLH t DPHL.5V V DIFF = V y - V z 9% 9% T DF t DSKEW = t DPLH - t DPHL Figure 5. RS-485/4 Driver Propagation Delays V OH RO V OL V -V A B / OUTPUT / t RPHL t RPLH INPUT / V O % t DZH t DHZ Figure. RS-485/4 Driver Enable and Disable Times Figure 7. RS-485/4 Receiver Propagation Delays 3V RE485.5V.5V RO t RZL t RLZ.5V OUTPUT NORMALLY LOW V OL +.5V V ID B R RO RO OUTPUT NORMALLY HIGH.5V V OH -.5V A C L t RZH t RHZ Figure 8. MAX3 RS-485/4 Receiver Enable and Disable Times Figure 9. RS-485/4 Receiver Propagation Delays Test Circuit 3

14 Detailed Description The 3V/5V, multiprotocol transceivers can be pin configured in a number of RS- 3 and RS-485/4 interface combinations. These circuit configurations are ideal for the design of RS-3 to RS-485 converters, multiprotocol buses, or any application that requires both RS-3 and RS-485 transceivers. The slew rate of these devices is on-the-fly pin programmable, allowing reduced EMI data rates, or up to Mbps RS-485 communications. Power consumption can be reduced to µa by using the shutdown function, but the RS-3 receivers remain active allowing other devices to query the interface controller. A flow-through pinout and the space-saving SSOP packages (available in the commercial and extended temperature ranges) facilitate board layout. Device Selection The contain RS-3 transceivers and an RS-485/4 transceiver. The primary difference between the devices is the multiplexing of the I/O pins. The MAX3 has common transmitter outputs and receiver inputs for its RS-3 and RS-485/4 transceivers, and common digital I/O pins. The MAX3 is optimized for multiprotocol operation on a single interface bus and comes in a -pin SSOP. The MAX3 has separate transmitter outputs and receiver inputs for its RS-3 and RS-485/4 transceivers, and common digital I/O pins. The MAX3 is optimized for multiplexing a single UART across two interface buses and comes in a 4-pin SSOP. The MAX3 has separate transmitter outputs and receiver inputs for its RS-3 and RS-485/4 transceivers, and separate digital I/O pins. The MAX3 is optimized for protocol translation between two interface buses and comes in a 8-pin SSOP. See Tables, Functional Diagrams, and the following descriptions for details on each device. MAX3 The MAX3 is a TX/RX RS-3 transceiver in RS- 3 mode, capable of RS-3-compliant communication. Assertion of RS-485/RS-3 converts the device to a single RS-485 transceiver by multiplexing the RS-3 I/O pins to an RS-485 driver and receiver pair. The logic inputs now control the driver input and the driver enable. One logic output carries the RS-485 receiver output, and the other is three-stated. The receiver input impedance is dependent on the device mode and is /4-unit load for RS-485 operation and 5kΩ for RS-3 operation. MAX3 The MAX3 is a TX/RX RS-3 transceiver in RS- 3 mode or a single RS-485/4 transceiver in RS-485 mode. When in RS-485 mode, the unused RS-3 transmitter and receiver output pins are disabled. When in RS-3 mode, the RS-485 transmitter outputs are disabled and the RS-3 receiver inputs are 5kΩ to GND. The RS-485 receiver inputs are always /8-unit load. Logic lines are shared between the two protocols and are used for signal inputs and as an RS-485 driver enable. MAX3 The MAX3 is a TX/RX RS-3 transceiver and a single RS-485/4 transceiver simultaneously. All drivers, receivers, and transmitters can be enabled or disabled by pin configuration. All outputs are high-z when not activated. RS-3 receiver inputs are 5kΩ when enabled, and RS-485 receiver inputs are /8-unit load. FAST Mode operation The FAST control pin is used to select the slew-rate limiting of the RS-3 transmitters and the RS-485/4 drivers. With FAST unasserted, the RS-3 transmitters and the RS-485/4 driver are slew-rate limited to reduce EMI. RS-3 data rates up to Mbps and RS- 485/4 data rates up to Mbps are possible when FAST is asserted. FAST can be changed during operation without interrupting data communications. Half-Duplex RS-485/4 Operation Asserting HDPLX places the MAX3/MAX3 in half-duplex mode. The RS-485 receiver inputs are internally connected to the driver outputs. The RS-485 driver outputs can be disabled by pulling DE485 low. HDPLX has no affect on RS-3 operation. Low-Power Shutdown The have an active-low shutdown control input,. When driven low, the charge pump and transmitters are shut down and supply current is reduced to µa. The RS-3 receiver outputs remain active if in RS-3 mode. The chargepump capacitors must be recharged when coming out of shutdown before resuming operation in either RS-3 or RS-485/4 mode (Figure ). Dual Charge-Pump Voltage Converter The s internal power supply consists of a regulated dual charge pump that provides output voltages of +5.5V (doubling charge pump) and -5.5V (inverting charge pump) for input voltages ( ) over the 3.V to 5.5V range. The charge pumps operate in a discontinuous mode: if the magnitude of either output voltage is less than 5.5V, the 4

15 charge pumps are enabled; if the magnitude of both output voltages exceeds 5.5V, the charge pumps are disabled. Each charge pump requires a flying capacitor (C, C) and a reservoir capacitor (C3, C4) to generate the V+ and V- supplies (see Functional Diagrams). RS-485/4 Transceivers The RS-485/4 transceivers feature fail-safe circuitry that guarantees a logic-high receiver output when the receiver inputs are open or shorted, or when they are connected to a terminated transmission line with all drivers disabled (see Fail-Safe). The also feature pin-selectable reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 5kbps (see Reduced EMI and Reflections). The transmitters may operate at speeds up to Mbps with the slew-rate limiting disabled. Drivers are short-circuit current limited and thermally limited to protect them against excessive power dissipation. Half-duplex communication is enabled by driving HDPLX high. Fail-Safe The guarantee a logichigh RS-485 receiver output when the receiver inputs are shorted or open, or when they are connected to a terminated transmission line with all drivers disabled. This is done by having the receiver threshold between -5mV and -mv. If the differential receiver input voltage (A-B) is greater than or equal to -5mV, RO is logic high. If A-B is less than or equal to -mv, RO is logic low. In the case of a terminated bus with all transmitters disabled, the receiver s differential input voltage is pulled to GND by the termination. This results in a logic high with a 5mV minimum noise margin. Unlike other fail-safe devices, the -5mV to -mv threshold complies with the ±mv EIA/TIA-485 standard. RS-3 Transceivers The RS-3 transmitters are inverting-level translators that convert CMOS-logic levels to ±5.V EIA/TIA-3-compliant levels. The transmitters are guaranteed at a 5kbps data rate in slewrate limited mode (FAST = GND) with worst-case loads of 3kΩ in parallel with pf. Data rates up to Mbps can be achieved by asserting FAST. When powered down or in shutdown, the MAX3/ MAX3/MAX3 outputs are high impedance and can be driven to ±V. The transmitter inputs do not have pullup resistors. Connect unused inputs to ground or. The receivers convert RS-3 signals to CMOS-logic output levels. All receivers have inverting outputs that remain active in shutdown. The MAX3/MAX3/ MAX3 permit their receiver inputs to be driven to Dia ±5V. Floating receiver input signals are pulled to ground through internal 5kΩ resistors, forcing the outputs to a logic high. The MAX3 has transmitter and receiver enable pins that allow its outputs to be threestated. Applications Information Capacitor Selection The capacitor type used for C C4 is not critical for proper operation; polarized or nonpolarized capacitors can be used. Ceramic chip capacitors with an X7R dielectric provide the best combination of performance, cost, and size. The charge pump requires.µf capacitors for 3.3V operation. For other supply voltages, see Table 3 for required capacitor values. Do not use values smaller than those listed in Table 3. Increasing the capacitor values reduces ripple on the transmitter outputs and slightly reduces power consumption. C, C3, and C4 can be changed without changing C s value. However, do not increase C without also increasing the values of C, C3, C4, and CBYPASS to maintain the proper ratios to the other capacitors. When using the minimum required capacitor values, make sure the capacitance value does not degrade excessively with temperature or voltage. This is typical of Y5V and Z5U dielectric ceramic capacitors. If in doubt, use capacitors with a larger nominal value. The capacitor s equivalent series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-. Power-Supply Decoupling In applications that are sensitive to power-supply noise, decouple to ground with a capacitor of the same value as reservoir capacitors C, C3, and C4. Connect the bypass capacitor as close to the IC as possible. RS-3 Transmitter Outputs when Exiting Shutdown Figure shows two transmitter outputs when exiting shutdown mode. As they become active, the two transmitter outputs are shown going to opposite RS-3 levels (one transmitter input is high, the other is low). Each transmitter is loaded with 3kΩ in parallel with pf. The transmitter outputs display no ringing or undesirable transients as they come out of shutdown. Note that the transmitters are enabled only when V- exceeds approximately -3V. 5

16 RS-3 Transmitters Table. MAX3 RS485 RS3 DI/TIN, DE485/TIN Z(B)/TOUT, Y(A)/TOUT X X /8 Unit Load X RS-485 Mode Table. MAX3 RS-485/ RS-3 DI/TIN, DE485/TIN TOUT, TOUT X X High-Z X High-Z Table 4. MAX3 RS-485/ RS-3 B/RIN, A/RIN ROUT, RO/ROUT X X X Inputs Open X X Table 5. MAX3 RS-485/ RS-3 RIN, RIN ROUT High-Z, RO/ROUT in RS-485 mode ROUT, RO/ROUT X X X Inputs Open X X Truth Tables RS-3 Receivers ROUT High-Z, RO/ROUT in RS-485 mode Table 3. MAX3 TE3 TIN,TIN TOUT, TOUT X X High-Z X X High-Z Table. MAX3 RE3 RIN, RIN ROUT, ROUT X X High-Z X X X Inputs open High Data Rates The maintain the RS-3 ±5.V required minimum transmitter output voltage even at high data rates. Figure shows a transmitter loopback test circuit. Figure shows a loopback test result at 5kbps, and Figure 3 shows the same test at kbps. Figure demonstrates a single slew-rate limited transmitter driven at 5kbps (FAST = GND) into an RS-3 load in parallel with pf. Figure 3 shows a single transmitter driven at Mbps (FAST asserted), loaded with an RS-3 receiver in parallel with pf. These transceivers maintain the RS-3 ±5.V minimum transmitter output voltage at data rates up to Mbps. 5 Transceivers on the Bus The standard RS-485 receiver input impedance is kω (one-unit load), and the standard driver can drive up to 3-unit loads. The MAX3 has a /4-unit load receiver input impedance (48kΩ), allowing up to 8 trans-

17 Truth Tables (continued) RS-485/4 Drivers Table 7. MAX3 RS485/RS3 DE485/TIN DI/TIN Z(B)/TOUT Y(A)/TOUT X X /8 Unit Load /8 Unit Load X /8 Unit Load /8 Unit Load X X X RS-3 Mode Table 8. MAX3 RS485/RS3 DE485/TIN DI/TIN Z(B) Y(A) X X X /8 Unit Load /8 Unit Load X X X /8 Unit Load /8 Unit Load X X X /8 Unit Load /8 Unit Load Table 9. MAX3 DE485 DI Z Y X X High-Z High-Z X X High-Z High-Z RS-485/4 Receivers Table. MAX3 OUTPUT RS485/RS3 HDPLX A - B* Y - Z* RO/ROUT X X X High-Z Up to -5mV X -mv X Floating X X -5mV X -mv X Floating X X X X RS-3 Mode *Y and Z correspond to pins Y(A)/TOUT and Z(B)/TOUT. A and B correspond to pins A/RIN and B/RIN. 7

18 Table. MAX3 SUPPLY VOLTAGE (V) C (µf) OUTPUT RS485/RS3 HDPLX A - B Y(A) - Z(B) RO/ROUT X X X High-Z up to -5mV X -mv X Floating X X -5mV X -mv X Floating X X X X RS-3 Mode Table. MAX3 OUTPUT RE485 A - B RO X X High-Z X X High-Z -5mV -mv Inputs Open Truth Tables (continued) Table 3. Required Minimum Capacitance Values C, C3, C4, C BYPASS (µf) +3. TO TO TO ceivers to be connected in parallel on one communication line. The MAX3/MAX3 have a /8-unit load receiver input impedance (9kΩ), allowing up to 5 transceivers to be connected in parallel on one communication line. Any combination of these devices and/or other RS-485 transceivers with a total of 3-unit loads or fewer can be connected to the line. The RS-485 driver outputs are /8-unit load when disabled This impedance may be reduced if the D pin is toggled at a high frequency. With no power applied ( = GND), the RS- 485 transmitter output impedances typically go to /- unit load on the MAX3/MAX3, and to one-unit load on the MAX3. Driver Output Protection Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus contention. The first, a foldback current limit on the output stage, provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics). The second, a thermal shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature becomes excessive. Protection Against Wiring Faults EIA/TIA-485 standards require a common input voltage range of -7V to +V to prevent damage to the device. The inputs are protected to RS-3 levels of ±5V for the receiver inputs and ±3.V for the transmitter/driver outputs. This provides additional protection for the RS-485 transceivers against ground differential or faults due to miswiring. RS-485/4 Reduced EMI and Reflections The can be configured for slew-rate limiting by pulling FAST low. This minimizes EMI and reduces reflections caused by improperly terminated cables. Operation in slew-rate limited mode reduces the amplitudes of high-frequency harmonics. 8

19 4µs/div MAX 3- FIG 5V/division TOUT V/div GND TOUT V/div Figure. MAX3 RS-3 Transmitter Outputs When Exiting Shutdown C C C BYPASS C+ C- C- C+ T_ IN MAX3 MAX3 MAX3 V+ V- T_ OUT C3 C4 µs/div MAX 3- FIG T IN T OUT 5V/div R OUT Figure. RS-3 Loopback Test Result at 5kbps, FAST = Low ns/div MAX 3- FIG3 T IN T OUT 5V/div R OUT R_ OUT R_ IN Figure 3. RS-3 Loopback Test Result at kbps, FAST = High GND Figure. Loopback Test Circuit RS-485/4 Line Length vs. Data Length The RS-485/4 standard covers line lengths up to 4 feet. For line lengths greater than 4 feet, use the repeater application shown in Figure 4. RS-3/RS-485 Protocol Translator Figure 5 shows the MAX3 configured as an RS- 3/RS-485 protocol translator. The direction of translation is controlled through the RTS signal (RIN). The 5k pf single-ended RS-3 receiver input signal is translated to a differential RS-485 transmitter output. Similarly, a differential RS-485 receiver input signal is translated to a single-ended RS-3 transmitter output. RS-3 data received on R IN is transmitted as an RS-485 signal on Z and Y. RS-485 signals received on A and B are transmitted as an RS-3 signal on T OUT. Multiprotocol Bus The Typical Operating Circuit shows a standard application for the MAX3. The MAX3 s output pins are multiplexed between RS-3 and RS-485 protocols by a microprocessor (µp). The µp also directs the shutdown functions, enable lines, and the duplex of the MAX3. Data is transmitted to the MAX3 UART through an SPI port. The UART asynchronously 9

20 RE485 DE485 RO DI NOTE: RE485 ON MAX3 ONLY Figure 4. RS-485 Line Repeater D R transfers data through the MAX3 to the pin-selected RS-3 or RS-485 protocal; see Table 4 for commonly used cable connections. A B Z Y Ω Ω MAX3 MAX3 MAX3 DATA IN DATA OUT RCV TX RTS C nf C3 nf 7 C+ 3.3V C+ C- MAX3 C TOUT TIN 4 ROUT RO 9 3 DI ROUT RE485 9 RIN DE RIN RE3 TE3 FAST A B Z Y V+ V- GND 4 C BYPASS nf C nf C4 nf Multiprotocol Bus Multiplexer The Typical Application Circuit shows the MAX3 configured as a multiprotocol bus multiplexer. The MAX3 separates the RS-3 and RS-485 lines, but shares the logic pins between modes. This application allows the µp to monitor a point-to-point RS-3 bus, and a multidrop RS-485 interface. The MAX3 UART asynchronously transfers data through the MAX3 to the pin-selected RS-3 or RS-485 protocol. Figure 5. Protocol Translator SPI is a trademark of Motorola, Inc.

21 Table 4. Cable Connections Commonly Used for EIA/TIA-3 and V.4 Asynchronous Interfaces EIA/TIA-3 STANDARD CONNECTOR PIN MAX3 UART SPI TX 3 RX RTS MAX3 MAX3 MAX3 CTS DI/TIN + PIN NUMBER EQUIVALENT MAX3 MAX3 MAX3 DCD Data Carrier Detect RD RIN Received Data 4 HDPLX TOUT 5 RO/ROUT RIN 7 DE/TIN TOUT 9 MAX3 8 ROUT RIN 9 8 GND FAST 4 Typical Application Circuit Y(A) 7 Z(B) RS-485 RS-3 FUNCTION (as seen by DTE) TD 3 TOUT Transmitted Data DTR 4 Data Terminal Ready SG 5 GND Signal Ground DSR Data Set Ready RTS 7 TOUT 8 8 Request to Send (= DTE ready) CTS 8 RIN 4 8 Clear to Send (= DCE ready) RI 9 Ring Indicator DB9 RJ45 µp RS-485/RS-3

22 MAX3 -PIN SSOP MAX3 4-PIN SSOP Pin Configurations V+ C+ C- V- DI/TIN DE485/TIN B/RIN A/RIN HDPLX RS-485/RS-3 TOP VIEW C+ C- GND Z(B)/TOUT Y(A)/TOUT ROUT RO/ROUT FAST V+ C+ C- V- DI/TIN DE485/TIN RIN RIN B A HDPLX RS-485/RS-3 C+ C- GND TOUT Z(B) Y(A) TOUT ROUT RO/ROUT FAST C+ 8 V+ C- GND TOUT Z Y TOUT ROUT ROUT RO RE MAX C+ C- V- TIN DI DE485 TIN RIN RIN B A TE3 FAST 4 5 RE3 8-PIN SSOP PART DUAL-MODE Selector Guide FLOW- THROUGH PIN-OUT RS-485 INPUT UNIT LOADS MAX3 No Yes /4 MAX3 No No /8 MAX3 Yes Yes /8 TRANSISTOR COUNT: 58 Chip Information

23 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to e D B N E A A H DIM A A B C D E e H L INCHES MILLIMETERS MIN MAX MIN MAX SEE VARIATIONS BSC.5 BSC L D D D D D INCHES MIN MAX MILLIMETERS MIN MAX C N 4L L L 4L 8L SSOP.EPS NOTES:. D&E DO NOT INCLUDE MOLD FLASH.. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED.5 MM (."). 3. CONTROLLING DIMENSION: MILLIMETERS. 4. MEETS JEDEC MO5. 5. LEADS TO BE COPLANAR WITHIN. MM. PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, SSOP, 5.3 MM APPROVAL DOCUMENT CONTROL NO. REV. -5 C Revision History Pages changed at Rev:,, 3 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 3 Maxim Integrated Products, San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.