+3.3V, ±15kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceivers

Transcription

1 ; ev 2; 4/9 +3.3V, ±15kV ES-Protected, Fail-Safe, General escription The 3.3V, ±15kV ES-protected, S-485/S-422 transceivers feature one driver and one receiver. These devices include fail-safe circuitry, guaranteeing a logic-high receiver output when receiver inputs are open or shorted. The receiver outputs a logic high if all transmitters on a terminated bus are disabled (high impedance). The include a hot-swap capability to eliminate false transitions on the bus during power-up or hot insertion. The MX37E/MX371E/MX372E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 25kbps. The MX373E/MX374E/MX375E also feature slewrate-limited drivers but allow transmit speeds up to 5kbps. The MX376E/MX377E/MX378E driver slew rates are not limited, making transmit speeds up to 16Mbps possible. The MX379E slew rate is pin selectable for 25kbps, 5kbps, and 16Mbps. The MX372E/MX375E/MX378E are intended for half-duplex communications, and the MX37E/ MX371E/MX373E/MX374E/MX376E/MX37 7E are intended for full-duplex communications. The MX379E is selectable for half-duplex or full-duplex operation. It also features independently programmable receiver and transmitter output phase through separate pins. The transceivers draw 8µ of supply current when unloaded or when fully loaded with the drivers disabled. ll devices have a 1/8-unit load receiver input impedance, allowing up to 256 transceivers on the bus. Lighting Systems Industrial Control Telecom Security Systems Instrumentation pplications Features 3.3V Operation Electrostatic ischarge (ES) Protection for S-485 I/O Pins ±15kV Human ody Model True Fail-Safe eceiver While Maintaining EI/TI-485 Compatibility Hot-Swap Input Structure on E and E Enhanced Slew-ate Limiting Facilitates Error- Free ata Transmission (MX37E MX375E/MX379E) Low-Current Shutdown Mode (Except MX371E/MX374E/MX377E) Pin-Selectable Full-/Half-uplex Operation (MX379E) Phase Controls to Correct for Twisted-Pair eversal (MX379E) llow Up to 256 Transceivers on the us vailable in Industry-Standard 8-Pin SO Package Ordering Information PT TEMP NGE PIN-PCKGE MX37EEP -4 C to +85 C 14 Plastic IP MX37EES -4 C to +85 C 14 SO MX37EP -4 C to +125 C 14 Plastic IP MX37ES -4 C to +125 C 14 SO MX371EEP -4 C to +85 C 8 Plastic IP MX371EES -4 C to +85 C 8 SO MX371EP -4 C to +125 C 8 Plastic IP MX371ES -4 C to +125 C 8 SO evices are available in both leaded (Pb) and lead(pb)-free packaging. Specify lead-free by adding a + after the part number. Ordering Information continued at end of data sheet. Selector Guide, Pin Configurations, and Typical Operating Circuits appear at end of data sheet. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim irect at , or visit Maxim s website at

2 +3.3V, ±15kV ES-Protected, Fail-Safe, SOLUTE MXIMUM TINGS (ll voltages referenced to GN) Supply Voltage ( )...+6V Control Input Voltage (E, E, SL, H/F, TXP, XP)...-.3V to +6V river Input Voltage (I)...-.3V to +6V river Output Voltage (Z, Y,, )...-8V to +13V eceiver Input Voltage (, )...-8V to +13V eceiver Input Voltage Full uplex (, )...-8V to +13V eceiver Output Voltage ()...-.3V to ( +.3V) river Output Current...±25m Stresses beyond those listed under bsolute Maximum atings 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. C ELECTICL CHCTEISTICS Continuous Power issipation (T = +7 C) 8-Pin SO (derate 5.88mW/ C above +7 C)...471mW 8-Pin Plastic IP (derate 9.9mW/ C above +7 C)...727mW 14-Pin SO (derate 8.33mW/ C above +7 C)...667mW 14-Pin Plastic IP (derate 1.mW/ C above +7 C)...8mW Operating Temperature anges MX37_EE...-4 C to +85 C MX37_E...-4 C to +125 C MX377EMS C to +125 C Junction Temperature C Storage Temperature ange C to +15 C Lead Temperature (soldering, 1s)...+3 C ( = 3.3V ±1%, T =T MIN to T MX, unless otherwise noted. Typical values are at = 3.3V and T = +25 C.) (Note 1) IVE PMETE SYMOL CONITIONS MIN TYP MX UNITS L = 1 (S422), Figure 1 2 ifferential river Output V O L = 54 (S485), Figure No load V Change in Magnitude of ifferential Output Voltage river Common-Mode Output Voltage Change in Magnitude of Common-Mode Voltage V O L = 1 or 54, Figure 1 (Note 2).2 V V OC L = 1 or 54, Figure 1 / 2 3 V V OC L = 1 or 54, Figure 1 (Note 2).2 V Input High Voltage V IH E, I, E, TXP, XP, H/F 2 V Input Low Voltage V IL E, I, E, TXP, XP, H/F.8 V Input Hysteresis V HYS E, I, E, TXP, XP, H/F 1 mv Input Current I IN1 E, I, E ±1 μ Input Impedance First Transition E 1 1 k Input Current I IN2 TXP, XP, H/F internal pulldown 1 4 μ SL Input High Voltage -.4 V SL Input Middle Voltage x.4 x.6 V SL Input Low Voltage.4 V SL Input Current Output Leakage (Y and Z) Full uplex I O SL = 75 SL = GN -75 E = GN, V IN = +12V 125 = GN or 3.6V V IN = -7V -1 μ μ 2

3 +3.3V, ±15kV ES-Protected, Fail-Safe, C ELECTICL CHCTEISTICS (continued) ( = 3.3V ±1%, T =T MIN to T MX, unless otherwise noted. Typical values are at = 3.3V and T = +25 C.) (Note 1) PMETE SYMOL CONITIONS MIN TYP MX UNITS river Short-Circuit Output Current river Short-Circuit Foldback Output Current V OUT 12V (Note 3) 4 25 I OS -7V V OUT (Note 3) ( - 1V) V OUT 12V (Note 3) 2 I OSF -7V V OUT 1V (Note 3) -2 Thermal-Shutdown Threshold T TS 175 C Thermal-Shutdown Hysteresis T TSH 15 C E = GN, V IN = +12V 125 Input Current ( and ) I, = GN or 3.6V V IN = -7V -1 ECEIVE eceiver ifferential Threshold Voltage V TH -7V V CM 12V mv eceiver Input Hysteresis V TH V + V = V 15 mv Output High Voltage V OH I O = -1m -.6 V Output Low Voltage V OL I O = 1m.4 V Three-State Output Current at eceiver I OZ V O ± 1 μ eceiver Input esistance IN -7V V CM 12V 96 k eceiver Output Short-Circuit Current SUPPLY CUENT I OS V V ±8 m No load, E =, E = Supply Current I CC No load, E =, E = No load, E =, E = m m μ m Supply Current in Shutdown Mode ES PTECTION I SHN E =, E = GN.5 1 μ ES Protection for Y, Z,, and Human ody Model ±15 kv Note 1: ll currents into the device are positive. ll currents out of the device are negative. ll voltages are referred to device ground, unless otherwise noted. Note 2: ΔV O and ΔV OC are the changes in V O and V OC, respectively, when the I input changes state. Note 3: The short-circuit output current applies to peak current just prior to foldback current limiting. The short-circuit foldback output current applies during current limiting to allow a recovery from bus contention. 3

4 +3.3V, ±15kV ES-Protected, Fail-Safe, IVE SWITCHING CHCTEISTICS MX37E/MX371E/MX372E/MX379E with SL = UNCONNECTE (25kbps) ( = 3.3V ±1%, T = T MIN to T MX, unless otherwise noted. Typical values are at = 3.3V and T = +25 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS river Propagation elay river ifferential Output ise or Fall Time ifferential river Output Skew t PLH - t PHL t PLH C L = 5pF, L = 54Ω, Figures 2 and 3 t PHL t, t F C L = 5pF, L = 54Ω, Figures 2 and ns t SKEW C L = 5pF, L = 54Ω, Figures 2 and 3 2 ns Maximum ata ate 25 kbps river Enable to Output High t ZH Figure 4 25 ns river Enable to Output Low t ZL Figure 5 25 ns river isable Time from Low t LZ Figure 5 1 ns river isable Time from High t HZ Figure 4 1 ns river Enable from Shutdown to Output High river Enable from Shutdown to Output Low t ZH(SHN) Figure 4 55 ns t ZL(SHN) Figure 5 55 ns Time to Shutdown t SHN ns ns ECEIVE SWITCHING CHCTEISTICS MX37E/MX371E/MX372E/MX379E with SL = UNCONNECTE (25kbps) ( = 3.3V ±1%, T = T MIN to T MX, unless otherwise noted. Typical values are at = 3.3V and T = +25 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS eceiver Propagation elay eceiver Output Skew t PLH - t PHL t PLH 2 C L = 15pF, Figures 6 and 7 t PHL 2 t SKEW C L = 15pF, Figures 6 and 7 3 ns Maximum ata ate 25 kbps eceiver Enable to Output Low t ZL Figure 8 5 ns eceiver Enable to Output High t ZH Figure 8 5 ns eceiver isable Time from Low t LZ Figure 8 5 ns eceiver isable Time from High t HZ Figure 8 5 ns eceiver Enable from Shutdown to Output High eceiver Enable from Shutdown to Output Low t ZH(SHN) Figure 8 4 ns t ZL(SHN) Figure 8 4 ns Time to Shutdown t SHN ns ns 4

5 +3.3V, ±15kV ES-Protected, Fail-Safe, IVE SWITCHING CHCTEISTICS MX373E/MX374E/MX375E/MX379E with SL = VCC (5kbps) ( = 3.3V ±1%, T = T MIN to T MX, unless otherwise noted. Typical values are at = 3.3V and T = +25 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS river Propagation elay river ifferential Output ise or Fall Time ifferential river Output Skew t PLH - t PHL t PLH 18 8 C L = 5pF, L = 54Ω, Figures 2 and 3 t PHL 18 8 t, t F C L = 5pF, L = 54Ω, Figures 2 and ns t SKEW C L = 5pF, L = 54Ω, Figures 2 and 3 1 ns Maximum ata ate 5 kbps river Enable to Output High t ZH Figure 4 25 ns river Enable to Output Low t ZL Figure 5 25 ns river isable Time from Low t LZ Figure 5 1 ns river isable Time from High t HZ Figure 4 1 ns river Enable from Shutdown to Output High river Enable from Shutdown to Output Low t ZH(SHN) Figure 4 45 ns t ZL(SHN) Figure 5 45 ns Time to Shutdown t SHN ns ns ECEIVE SWITCHING CHCTEISTICS MX373E/MX374E/MX375E/MX379E with SL = VCC (5kbps) ( = 3.3V ±1%, T = T MIN to T MX, unless otherwise noted. Typical values are at = 3.3V and T = +25 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS eceiver Propagation elay eceiver Output Skew t PLH - t PHL t PLH 2 C L = 15pF, Figures 6 and 7 t PHL 2 t SKEW C L = 15pF, Figures 6 and 7 3 ns Maximum ata ate 5 kbps eceiver Enable to Output Low t ZL Figure 8 5 ns eceiver Enable to Output High t ZH Figure 8 5 ns eceiver isable Time from Low t LZ Figure 8 5 ns eceiver isable Time from High t HZ Figure 8 5 ns eceiver Enable from Shutdown to Output High eceiver Enable from Shutdown to Output Low t ZH(SHN) Figure 8 4 ns t ZL(SHN) Figure 8 4 ns Time to Shutdown t SHN ns ns 5

6 +3.3V, ±15kV ES-Protected, Fail-Safe, IVE SWITCHING CHCTEISTICS MX376E/MX377E/MX378E/MX379E with SL = GN (16Mbps) ( = 3.3V ±1%, T = T MIN to T MX, unless otherwise noted. Typical values are at = 3.3V and T = +25 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS river Propagation elay river ifferential Output ise or Fall Time ifferential river Output Skew t PLH - t PHL t PLH 5 C L = 5pF, L = 54Ω, Figures 2 and 3 t PHL 5 t, t F C L = 5pF, L = 54Ω, Figures 2 and 3 15 ns t SKEW C L = 5pF, L = 54Ω, Figures 2 and 3 8 ns Maximum ata ate 16 Mbps river Enable to Output High t ZH Figure 4 15 ns river Enable to Output Low t ZL Figure 5 15 ns river isable Time from Low t LZ Figure 5 1 ns river isable Time from High t HZ Figure 4 1 ns river Enable from Shutdown to Output High river Enable from Shutdown to Output Low t ZH(SHN) Figure ns t ZL(SHN) Figure ns Time to Shutdown t SHN ns ns ECEIVE SWITCHING CHCTEISTICS MX376E/MX377E/MX378E/MX379E with SL = GN (16Mbps) ( = 3.3V ±1%, T = T MIN to T MX, unless otherwise noted. Typical values are at = 3.3V and T = +25 C.) PMETE SYMOL CONITIONS MIN TYP MX UNITS eceiver Propagation elay eceiver Output Skew t PLH - t PHL t PLH 4 75 C L = 15pF, Figures 6 and 7 t PHL 4 75 t SKEW C L = 15pF, Figures 6 and 7 8 ns Maximum ata ate 16 Mbps eceiver Enable to Output Low t ZL Figure 8 5 ns eceiver Enable to Output High t ZH Figure 8 5 ns eceiver isable Time from Low t LZ Figure 8 5 ns eceiver isable Time from High t HZ Figure 8 5 ns eceiver Enable from Shutdown to Output High eceiver Enable from Shutdown to Output Low t ZH(SHN) Figure 8 18 ns t ZL(SHN) Figure 8 18 ns Time to Shutdown t SHN ns ns 6

7 +3.3V, ±15kV ES-Protected, Fail-Safe, Typical Operating Characteristics ( = 3.3V, T = +25 C, unless otherwise noted. Note: The MX377EMS/P meets specification over temperature.) SUPPLY CUENT (m) OUTPUT HIGH VOLTGE (V) SUPPLY CUENT vs. TEMPETUE E = E = TEMPETUE ( C) ECEIVE OUTPUT HIGH VOLTGE vs. TEMPETUE I O = -1m TEMPETUE ( C) MX37E toc1 MX37E toc4 OUTPUT CUENT (m) OUTPUT LOW VOLTGE (V) OUTPUT CUENT vs. ECEIVE OUTPUT HIGH VOLTGE OUTPUT HIGH VOLTGE (V) ECEIVE OUTPUT LOW VOLTGE vs. TEMPETUE I O = -1m TEMPETUE ( C) MX37E toc2 MX37E toc5 OUTPUT CUENT (m) OUTPUT CUENT (m) OUTPUT CUENT vs. ECEIVE OUTPUT LOW VOLTGE OUTPUT HIGH VOLTGE (V) IVE OUTPUT CUENT vs. IFFEENTIL OUTPUT VOLTGE IFFEENTIL OUTPUT VOLTGE (V) MX37E toc3 MX37E toc6 IFFEENTIL OUTPUT VOLTGE (V) IVE IFFEENTIL OUTPUT VOLTGE vs. TEMPETUE L = 54Ω TEMPETUE ( C) XMX37E toc7 OUTPUT CUENT (m) OUTPUT CUENT vs. TNSMITTE OUTPUT HIGH VOLTGE OUTPUT HIGH VOLTGE (V) MX37E toc8 OUTPUT CUENT (m) OUTPUT CUENT vs. TNSMITTE OUTPUT LOW VOLTGE OUTPUT LOW VOLTGE (V) MX37E toc9 7

8 +3.3V, ±15kV ES-Protected, Fail-Safe, Typical Operating Characteristics (continued) ( = 3.3V, T = +25 C, unless otherwise noted. Note: The MX377EMS/P meets specification over temperature.) SHUTOWN CUENT (μ) IVE PPGTION ELY (ns) SHUTOWN CUENT vs. TEMPETUE TEMPETUE ( C) IVE PPGTION ELY vs. TEMPETUE (16Mbps) t PLH t PHL MX37E toc1 MX37E toc13 IVE PPGTION ELY (ns) IVE PPGTION ELY (ns) IVE PPGTION ELY vs. TEMPETUE (25kbps) t PLH tphl TEMPETUE ( C) ECEIVE PPGTION ELY vs. TEMPETUE (25kbps N 5kbps) t PLH t PHL MX37E toc11 MX37E toc14 IVE PPGTION ELY (ns) ECEIVE PPGTION ELY (ns) IVE PPGTION ELY vs. TEMPETUE (5kbps) t PLH t PHL TEMPETUE ( C) ECEIVE PPGTION ELY vs. TEMPETUE (16Mbps) t PLH t PHL MX37E toc12 MX37E toc TEMPETUE ( C) TEMPETUE ( C) TEMPETUE ( C) IVE PPGTION ELY (25kbps) MX37E toc16 ECEIVE PPGTION ELY (25kbps N 5kbps) MX37E toc17 I 2V/div V - V 1V/div V Y - V Z 2V/div 2V/div 1μs/div 2ns/div 8

9 +3.3V, ±15kV ES-Protected, Fail-Safe, Typical Operating Characteristics (continued) ( = 3.3V, T = +25 C, unless otherwise noted. Note: The MX377EMS/P meets specification over temperature.) IVE PPGTION ELY (5kbps) 4ns/div MX37E toc18 I 2V/div V Y - V Z 2V/div IVE PPGTION ELY (16Mbps) 1ns/div MX37E toc19 I 2V/div V Z 1V/div V Y 1V/div ECEIVE PPGTION ELY (16Mbps) 2ns/div MX37E toc2 V 1V/div V 1V/div 2V/div Test Circuits and Waveforms Y 3V L /2 E V O L /2 V OC I Y Z V O L C L Z Figure 1. river C Test Load Figure 2. river Timing Test Circuit I /2 t PLH t PHL 1/2 V O Z Y V O V IFF V O -V O 1/2 V O 1% t V IFF = V (Y) - V (Z) 9% 9% t F 1% t SKEW = t PLH - t PHL Figure 3. river Propagation elays 9

10 +3.3V, ±15kV ES-Protected, Fail-Safe, E OUT O 3V GENETO 5Ω t ZH, t ZH(SHN) V OM = ( + V OH ) / 2 Test Circuits and Waveforms (continued) S1 C L 5pF L = 5Ω OUT / 2.25V V OH t HZ Figure 4. river Enable and isable Times (t HZ, t ZH, t ZH(SHN) ) S1 L = 5Ω O 3V OUT C L 5pF GENETO 5Ω E t ZL, t ZL(SHN) / 2 OUT V OM = (V OL + ) / 2 V OL.25V t LZ Figure 5. river Enable and isable Times (t ZL, t LZ, t LZ(SHN) ) 1

11 +3.3V, ±15kV ES-Protected, Fail-Safe, TE Figure 6. eceiver Propagation elay Test Circuit V I +1.5V -1.5V S3 ECEIVE OUTPUT GENETO V I Test Circuits and Waveforms (continued) 5Ω V OH 1.5V V OL t PLH THE ISE TIME N FLL TIME OF INPUTS N < 4ns Figure 7. eceiver Propagation elays C L 15pF 1kΩ S1 S2 t PHL +1V -1V S1 OPEN S2 CLOSE S3 = +1.5V 3V S1 CLOSE S2 OPEN S3 = -1.5V 3V E E 1.5V t ZH, t ZH(SHN) t ZL, t ZL(SHN) V OH V OH / 2 (V OL + ) / 2 V OL S1 OPEN S2 CLOSE S3 = +1.5V 3V S1 CLOSE S2 OPEN S3 = -1.5V 3V E 1.5V t HZ E 1.5V t LZ.25V V OH.25V V OL Figure 8. eceiver Enable and isable Times 11

12 +3.3V, ±15kV ES-Protected, Fail-Safe, MX37E MX373E MX376E MX371E MX374E MX377E FULL-UPLEX EVICES PIN MX372E MX375E MX378E HLF- UPLEX EVICES MX379E FULL- UPLE X MOE HLF- UPLE X MOE NME 1 1 H/F E E I FUNCTION Pin escription Half-/Full-uplex Select Pin. Connect H/F to for halfduplex mode; connect to GN or leave unconnected for full-duplex mode. eceiver Output. When E is low and if ( - ) -5mV, is high; if ( - ) -2mV, is low. eceiver Output Enable. rive E low to enable ; is high impedance when E is high. rive E high and E low to enter low-power shutdown mode. E is a hotswap input (see the Hot-Swap Capability section for details). river Output Enable. rive E high to enable driver outputs. These outputs are high impedance when E is low. rive E high and E low to enter low-power shutdown mode. E is a hot-swap input (see the Hot- Swap Capability section for details). river Input. With E high, a low on I forces noninverting output low and inverting output high. Similarly, a high on I forces noninverting output high and inverting output low. 6 6 SL Slew-ate Limit Selector Pin. Connect SL to ground for 16Mbps communication rate; connect to for 5kbps communication rate. Leave unconnected for 25kbps communication rate. 6, GN Ground 8 8 TXP Transmitter Phase. Connect TXP to ground or leave unconnected for normal transmitter phase/polarity. Connect to to invert the transmitter phase/polarity Y Noninverting river Output 9 Y Noninverting river Output and Noninverting eceiver Input* Z Inverting river Output 1 Z Inverting river Output and Inverting eceiver Input* Inverting eceiver Input 11 eceiver Input esistors* 7 Inverting eceiver Input and Inverting river Output 12

13 +3.3V, ±15kV ES-Protected, Fail-Safe, MX37E MX373E MX376E MX371E MX374E MX377E FULL-UPLEX EVICES PIN MX372E MX375E MX378E HLF- UPLEX EVICES MX379E FULL- UPLE X MOE HLF- UPLE X MOE NME Noninverting eceiver Input 12 eceiver Input esistors* XP Pin escription (continued) FUNCTION Noninverting eceiver Input and Noninverting river Output eceiver Phase. Connect XP to GN or leave unconnected for normal transmitter phase/polarity. Connect to to invert receiver phase/polarity Positive Supply = 3.3V ±1%. ypass to GN with a.1μf capacitor. 1, 8, 13 N.C. No Connect. Not internally connected. Can be connected to GN. *MX379E only. In half-duplex mode, the driver outputs serve as receiver inputs. The full-duplex receiver inputs ( and ) still have a 1/8-unit load, but are not connected to the receiver. MX37E/MX373E/MX376E TNSMITTING INPUTS OUTPUTS E E I Z Y X X 1 1 X High-Z High-Z 1 X Shutdown INPUTS ECEIVING OUTPUT E E, X -5mV 1 X -2mV X Open/ shorted 1 1 X High-Z 1 X Shutdown 1 Function Tables MX371E/MX374E/MX377E TNSMITTING INPUT OUTPUTS I Z Y ECEIVING INPUTS OUTPUT, -5mV 1-2mV Open/shorted 1 13

14 +3.3V, ±15kV ES-Protected, Fail-Safe, MX372E/MX375E/MX378E TNSMITTING INPUTS OUTPUTS E E I /Z /Y X X 1 1 X High-Z High-Z 1 X Shutdown MX379E Function Tables (continued) ECEIVING INPUTS OUTPUTS E E - X -5mV 1 X -2mV X Open/ shorted 1 1 X High-Z 1 X Shutdown TNSMITTING INPUTS OUTPUTS TXP E E I Z Y X X X X 1 1 X X High-Z High-Z X 1 X Shutdown 1 ECEIVING INPUTS OUTPUTS H/F XP E E, Y, Z X > -5mV X 1 X < -2mV X 1 X > -5mV X 1 X < -2mV X 1 1 X > -5mV 1 1 X < -2mV 1 1 X > -5mV 1 1 X < -2mV 1 X Open/shorted X 1 1 X Open/shorted 1 1 X Open/shorted X 1 1 X Open/shorted X X 1 1 X X High-Z X X 1 X X Shutdown X = on t care; shutdown mode, driver and receiver outputs are high impedance. 14

15 +3.3V, ±15kV ES-Protected, Fail-Safe, etailed escription The high-speed transceivers for S-485/S-422 communication contain one driver and one receiver. These devices feature fail-safe circuitry, which 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 the Fail-Safe section). The MX37E/MX372E/MX373E/MX375E/ MX376E/MX378E/MX379E also feature a hotswap capability allowing line insertion without erroneous data transfer (see the Hot Swap Capability section). The MX37E/MX371E/MX372E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 25kbps. The MX373E/MX374E/MX375E also offer slew-rate limits allowing transmit speeds up to 5kbps. The MX376E/MX377E/MX378Es driver slew rates are not limited, making transmit speeds up to 16Mbps possible. The MX379E s slew rate is selectable between 25kbps, 5kbps, and 16Mbps by driving a selector pin with a three-state driver. The MX372E/MX375E/MX378E are half-duplex transceivers, while the MX37E/MX371E/ MX373E/MX374E/MX376E/MX377E are fullduplex transceivers. The MX379E is selectable between half- and full-duplex communication by driving a selector pin (SL) high or low, respectively. ll devices operate from a single 3.3V supply. rivers are output short-circuit current limited. Thermal-shutdown circuitry protects drivers against excessive power dissipation. When activated, the thermal-shutdown circuitry places the driver outputs into a high-impedance state. eceiver Input Filtering The receivers of the MX37E MX375E, and the MX379E when operating in 25kbps or 5kbps mode, incorporate input filtering in addition to input hysteresis. This filtering enhances noise immunity with differential signals that have very slow rise and fall times. eceiver propagation delay increases by 25% due to this filtering. Fail-Safe The MX37E family guarantees a logic-high 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 setting the receiver input threshold between -5mV and -2mV. If the differential receiver input voltage ( - ) is greater than or equal to -5mV, is logic high. If - is less than or equal to -2mV, is logic low. In the case of a terminated bus with all transmitters disabled, the receiver s differential input voltage is pulled to V by the termination. With the receiver thresholds of the MX37E family, this results in a logic high with a 5mV minimum noise margin. Unlike previous fail-safe devices, the -5mV to -2mV threshold complies with the ±2mV EI/TI-485 standard. Hot-Swap Capability (Except MX371E/MX374E/MX377E) Hot-Swap Inputs When circuit boards are inserted into a hot, or powered, backplane, differential disturbances to the data bus can lead to data errors. Upon initial circuit board insertion, the data communication processor undergoes its own power-up sequence. uring this period, the processor s logic-output drivers are high impedance and are unable to drive the E and E inputs of these devices to a defined logic level. Leakage currents up to ±1µ from the high-impedance state of the processor s logic drivers could cause standard CMOS enable inputs of a transceiver to drift to an incorrect logic level. dditionally, parasitic circuit board capacitance could cause coupling of or GN to the enable inputs. Without the hot-swap capability, these factors could improperly enable the transceiver s driver or receiver. When rises, an internal pulldown circuit holds E low and E high. fter the initial power-up sequence, the pulldown circuit becomes transparent, resetting the hot-swap tolerable input. Hot-Swap Input Circuitry The enable inputs feature hot-swap capability. t the input there are two NMOS devices, M1 and M2 (Figure 9). When ramps from zero, an internal 1µs timer turns on M2 and sets the S latch, which also turns on M1. Transistors M2, a 5µ current sink, and M1, a 1µ current sink, pull E to GN through a 5kΩ resistor. M2 is designed to pull E to the disabled state against an external parasitic capacitance up to 1pF that can drive E high. fter 1µs, the timer deactivates M2 while M1 remains on, holding E low against three-state leakages that can drive E high. M1 remains on until an external source overcomes the required input current. t this time, the S latch resets and M1 turns off. When M1 turns off, E reverts to a standard, high-impedance CMOS input. Whenever drops below 1V, the hot-swap input is reset. For E there is a complementary circuit employing two PMOS devices pulling E to. 15

16 +3.3V, ±15kV ES-Protected, Fail-Safe, E TIME TIME 5kΩ M1 1μ 5μ 1μs M2 S LTCH E (HOT SWP) Figure 9. Simplified Structure of the river Enable Pin (E) MX379E Programming The MX379E has several programmable operating modes. Transmitter rise and fall times are programmable, resulting in maximum data rates of 25kbps, 5kbps, and 16Mbps. To select the desired data rate, drive SL to one of three possible states by using a three-state driver:, GN, or unconnected. For 25kbps operation, set the three-state device in highimpedance mode or leave SL unconnected. For 5kbps operation, drive SL high or connect it to. For 16Mbps operation, drive SL low or connect it to GN. SL can be changed during operation without interrupting data communications. Occasionally, twisted-pair lines are connected backward from normal orientation. The MX379E has two pins that invert the phase of the driver and the receiver to correct this problem. For normal operation, drive TXP and XP low, connect them to ground, or leave them unconnected (internal pulldown). To invert the driver phase, drive TXP high or connect it to. To invert the receiver phase, drive XP high or connect it to. Note that the receiver threshold is positive when XP is high. The MX379E can operate in full- or half-duplex mode. rive the H/F pin low, leave it unconnected (internal pulldown), or connect it to GN for full-duplex operation. rive H/F high for half-duplex operation. In full-duplex mode, the pin configuration of the driver and receiver is the same as that of a MX37E. In halfduplex mode, the receiver inputs are switched to the driver outputs, connecting outputs Y and Z to inputs and, respectively. In half-duplex mode, the internal full-duplex receiver input resistors are still connected to pins 11 and 12. ±15kV ES Protection s with all Maxim devices, ES-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the MX37E family of devices have extra protection against static electricity. Maxim s engineers have developed state-of-the-art structures to protect these pins against ES of ±15kV without damage. The ES structures withstand high ES in all states: normal operation, shutdown, and powered down. fter an ES event, the keep working without latchup or damage. ES protection can be tested in various ways. The transmitter outputs and receiver inputs of the are characterized for protection to the following limits: ±15kV using the Human ody Model ±6kV using the Contact ischarge method specified in IEC ES Test Conditions ES performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test setup, test methodology, and test results. Human ody Model Figure 1a shows the Human ody Model, and Figure 1b shows the current waveform it generates when discharged into a low impedance. This model consists of a 1pF capacitor charged to the ES voltage of interest, which is then discharged into the test device through a 1.5kΩ resistor. IEC The IEC standard covers ES testing and performance of finished equipment. However, it does not specifically refer to integrated circuits. The MX37E family of devices helps you design equipment to meet IEC 1-4-2, without the need for additional ES-protection components. The major difference between tests done using the Human ody Model and IEC is higher peak 16

17 +3.3V, ±15kV ES-Protected, Fail-Safe, HIGH- VOLTGE C SOUCE C 1MΩ CHGE-CUENT- LIMIT ESISTO Cs 1pF 15Ω ISCHGE ESISTNCE STOGE CPCITO Figure 1a. Human ody ES Test Model HIGH- VOLTGE C SOUCE C 5MΩ TO 1MΩ CHGE-CUENT- LIMIT ESISTO Cs 15pF 33Ω ISCHGE ESISTNCE STOGE CPCITO EVICE UNE TEST EVICE UNE TEST MPS I P 1% 9% 36.8% 1% t L Ir TIME t L CUENT WVEFOM Figure 1b. Human ody Current Waveform IPEK I 1% 9% 1% PEK-TO-PEK INGING (NOT WN TO SCLE) t r =.7ns TO 1ns 3ns 6ns t Figure 1c. IEC ES Test Model current in IEC 1-4-2, because series resistance is lower in the IEC model. Hence, the ES withstand voltage measured to IEC is generally lower than that measured using the Human ody Model. Figure 1c shows the IEC model, and Figure 1d shows the current waveform for IEC ES Contact ischarge test. The air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized. Machine Model The machine model for ES tests all pins using a 2pF storage capacitor and zero discharge resistance. The objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and assembly. Of course, all pins require this protection, not just S-485 inputs and outputs. Figure 1d. IEC ES Generator Current Waveform pplications Information 256 Transceivers on the us The standard S-485 receiver input impedance is 12kΩ (1-unit load), and the standard driver can drive up to 32- unit loads. The MX37E family of transceivers has a 1/8-unit load receiver input impedance (96kΩ), allowing up to 256 transceivers to be connected in parallel on one communication line. ny combination of these devices as well as other S-485 transceivers with a total of 32- unit loads or fewer can be connected to the line. educed EMI and eflections The MX37E/MX371E/MX372E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 25kbps. The MX373E/MX374E/MX375E offer higher driver output slew-rate limits, allowing transmit speeds up to 5kbps. The MX379E with SL = or unconnected, are slew-rate limited. With SL unconnected, the MX379E error-free data transmission is up to 25kbps; with SL connected to the data transmit speeds up to 5kbps. 17

18 +3.3V, ±15kV ES-Protected, Fail-Safe, Low-Power Shutdown Mode (Except MX371E/MX374E/MX377E) Low-power shutdown mode is initiated by bringing both E high and E low. In shutdown, the devices typically draw only 5n of supply current. E and E can be driven simultaneously; the parts are guaranteed not to enter shutdown if E is high and E is low for less than 5ns. If the inputs are in this state for at least 6ns, the parts are guaranteed to enter shutdown. Enable times t ZH and t ZL (see the Switching Characteristics section) assume the part was not in a low-power shutdown state. Enable times t ZH(SHN) and t ZL(SHN) assume the parts were shut down. It takes drivers and receivers longer to become enabled from low-power shutdown mode (t ZH(SHN), t ZL(SHN) ) than from driver/receiver-disable mode (t ZH, t ZL ). E E I Z MX37E/MX371E/MX373E/ MX374E/MX376E/MX377E/ MX379E (FULL-UPLEX) 12Ω Y 12Ω T IN T OUT river 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 the Typical Operating Characteristics). The second, a thermal-shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature becomes excessive. Line Length The S-485/S-422 standard covers line lengths up to 4ft. For line lengths greater than 4ft, use the repeater application shown in Figure 11. Typical pplications The MX372E/MX375E/MX378E/MX379E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 12 and 13 show typical network applications circuits. To minimize reflections, terminate the line at both ends in its characteristic impedance, and keep stub lengths off the main line as short as possible. The slew-rate-limited MX372E/MX375E and the two modes of the MX379E are more tolerant of imperfect termination. Chip Information TNSISTO COUNT: 1228 PCESS: icmos Figure 11. Line epeater for MX37E/MX371E/MX373E/ MX374E/MX376E/MX377E/MX379E in Full-uplex Mode I E 12Ω 12Ω E I E E MX372E MX375E MX378E MX379E (HLF-UPLEX) I E E I E E Figure 12. Typical Half-uplex S-485 Network 18

19 +3.3V, ±15kV ES-Protected, Fail-Safe, 12Ω E E Z I 12Ω Y Y Z I E E Figure 13. Typical Full-uplex S-485 Network Y Z I E E Y 12Ω Z 12Ω MX37E MX373E MX376E MX379E (FULL-UPLEX) I E E Selector Guide PT HLF/FULL- UPLEX T TE (Mbps) SLEW-TE LIMITE LOW-POWE SHUTOWN ECEIVE/ IVE ENLE TNSCEIVES ON US MX37E Full.25 Yes Yes Yes MX371E Full.25 Yes No No MX372E Half.25 Yes Yes Yes MX373E Full.5 Yes Yes Yes MX374E Full.5 Yes No No MX375E Half.5 Yes Yes Yes MX376E Full 16 No Yes Yes MX377E Full 16 No No No MX378E Half 16 No Yes Yes MX379E Selectable Selectable Selectable Yes Yes PINS 19

20 +3.3V, ±15kV ES-Protected, Fail-Safe, N.C. E E I GN GN I GN IP/SO IP/SO N.C. Z Y N.C. Z Y Pin Configurations and Typical Operating Circuits I 5 2 1, 8, 13 N.C. I 3 2 E 4 E GN 3 6, 7 1 GN.1μF Y Z.1μF t MX37E MX373E MX376E TYPICL FULL-UPLEX OPETING CICUIT Y Z t MX371E MX374E MX377E t t E GN E I I 4 GN TYPICL FULL-UPLEX OPETING CICUIT E E I GN E E I GN.1μF t MX372E MX375E MX378E t E I IP/SO E TYPICL HLF-UPLEX OPETING CICUIT NOTE: PIN LELS Y N Z ON TIMING, TEST, N WVEFOMS IGMS. EFE TO PINS N WHEN E IS HIGH. 2

21 +3.3V, ±15kV ES-Protected, Fail-Safe, TOP VIEW H/F 1 2 E 3 E 4 I 5 SL 6 GN 7 Pin Configurations and Typical Operating Circuits (continued) E MX379E 14 XP XP MX379E 11 H/F 1 Z TXP Z 9 8 Y TXP Y IP/SO I NOTE: SWITCH POSITIONS INICTE FO H/F = GN. GN E SL 21

22 +3.3V, ±15kV ES-Protected, Fail-Safe, PT TEMP NGE PIN-PCKGE MX372EEP -4 C to +85 C 8 Plastic IP MX372EES -4 C to +85 C 8 SO MX372EP -4 C to +125 C 8 Plastic IP MX372ES -4 C to +125 C 8 SO MX373EEP -4 C to +85 C 14 Plastic IP MX373EES -4 C to +85 C 14 SO MX373EP -4 C to +125 C 14 Plastic IP MX373ES -4 C to +125 C 14 SO MX374EEP -4 C to +85 C 8 Plastic IP MX374EES -4 C to +85 C 8 SO MX374EP -4 C to +125 C 8 Plastic IP MX374ES -4 C to +125 C 8 SO MX375EEP -4 C to +85 C 8 Plastic IP MX375EES -4 C to +85 C 8 SO MX375EP -4 C to +125 C 8 Plastic IP MX375ES -4 C to +125 C 8 SO Ordering Information (continued) PT TEMP NGE PIN-PCKGE MX376EEP -4 C to +85 C 14 Plastic IP MX376EES -4 C to +85 C 14 SO MX376EP -4 C to +125 C 14 Plastic IP MX376ES -4 C to +125 C 14 SO MX377EEP -4 C to +85 C 8 Plastic IP MX377EES -4 C to +85 C 8 SO MX377EP -4 C to +125 C 8 Plastic IP MX377ES -4 C to +125 C 8 SO MX377EMS/P -55 C to +125 C 8 SO MX378EEP -4 C to +85 C 8 Plastic IP MX378EES -4 C to +85 C 8 SO MX378EP -4 C to +125 C 8 Plastic IP MX378ES -4 C to +125 C 8 SO MX379EEP -4 C to +85 C 14 Plastic IP MX379EES -4 C to +85 C 14 SO MX379EP -4 C to +125 C 14 Plastic IP MX379ES -4 C to +125 C 14 SO evices are available in both leaded (Pb) and lead(pb)-free packaging. Specify lead-free by adding a + after the part number. Package Information For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates ohs status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of ohs status. PCKGE TYPE PCKGE COE OCUMENT NO. 8 Plastic IP P Plastic IP P SO S SO S

23 +3.3V, ±15kV ES-Protected, Fail-Safe, Package Information (continued) For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates ohs status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of ohs status. N 1 TOP VIEW E H INCHES MILLIMETES IM MIN MX MIN MX C e.5 SC 1.27 SC E H L VITIONS: IM INCHES MILLIMETES MIN MX MIN MX N MS C SOICN.EPS C e 1 FNT VIEW L SIE VIEW -8 PPIETY INFOMTION TITLE: PCKGE OUTLINE,.15" SOIC PPVL OCUMENT CONTL NO. EV

24 +3.3V, ±15kV ES-Protected, Fail-Safe, EVISION NUME EVISION TE ESCIPTION evision History PGES CHNGE 1/2 Initial release. 2 4/9 dded /P information to reflect new characterization information for military temperature version. 2, 3, 7, 8, 12, 13, 19, 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. 24 Maxim Integrated Products, 12 San Gabriel rive, Sunnyvale, C Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.