19-2218; Rev 1; 5/02 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package Features ♦ Space-Saving 8-Pin SOT Package ♦ Guaranteed 20Mbps Data Rate ♦ Operates from a Single +3.3V Supply ♦ 6ns (max) Transmitter and Receiver Skew ♦ Hot-Swap Feature ♦ Interoperable with +5V Logic ♦ Allows up to 256 Transceivers on the Bus ♦ 1µA Low-Power Shutdown Mode ♦ 1.7mA Operating Supply Current ♦ -7V to +12V Common-Mode Range ♦ Current Limiting and Thermal Shutdown ♦ Half-Duplex Operation ♦ Automotive Temperature Range Variants Ordering Information TEMP RANGE MAX3362EKA -40°C to +85°C 8 SOT23 AAJL MAX3362AKA -40°C to +125°C 8 SOT23 AALL Applications Clock/Data Distribution Telecom Equipment Security Equipment Point-of-Sale Equipment Industrial Controls Pin Configuration and Functional Diagram appear at end of data sheet. Typical Operating Circuit 120Ω 120Ω B DI PINTOP MARK PACKAGE PART B DE D D DE RO A B A B A DI A R R RE RO RE R R D D MAX3362 DI DE RO RE DI DE RO RE ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX3362 General Description The MAX3362 low-power, high-speed transceiver for RS-485/RS-422 communication operates from a single +3.3V power supply. The device contains one differential transceiver consisting of a line driver and receiver. The transceiver operates at data rates up to 20Mbps, with an output skew of less than 6ns. Driver and receiver propagation delays are guaranteed below 50ns. This fast switching and low skew make the MAX3362 ideal for multidrop clock/data distribution applications. The output level is guaranteed at +1.5V with a standard 54Ω load, compliant with RS-485 specifications. The transceiver draws 1.7mA supply current when unloaded or fully loaded with the drivers disabled. Additionally, the MAX3362 has a low-power shutdown mode, reducing the supply current to 1µA. The MAX3362 has a 1/8-unit-load receiver input impedance, allowing up to 256 transceivers on the bus. The MAX3362 is designed for half-duplex communication. The device has a hot-swap feature that eliminates false transitions on the data cable during circuit initialization. The drivers are short-circuit current limited, and a thermal shutdown circuit protects against excessive power dissipation. The MAX3362 is available in an 8-pin SOT package and specified over industrial and automotive temperature ranges. MAX3362 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package ABSOLUTE MAXIMUM RATINGS All voltages with respect to GND. VCC, RE, DE, DI ......................................................-0.3V to +6V Receiver Input Voltages, Driver Output Voltages (A, B) .......................................................-8V to +13V Receiver Input Current, Driver Output Current (A, B) .................................................................250mA |VA - VB|..................................................................................+8V Receiver Output Voltage (RO)....................-0.3V to (VCC + 0.3V) Continuous Power Dissipation (TA = +70°C) 8-Pin SOT (derate 9.7mW/°C above +70°C) ............... 777mW Operating Temperature Range MAX3362E__ .................................................. -40°C to +85°C MAX3362A__ ................................................ -40°C to +125°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10s) .................................+300°C 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. DC ELECTRICAL CHARACTERISTICS (VCC = +3.3V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DRIVER Differential Driver Output Change in Magnitude of Differential Output Voltage Driver Common-Mode Output Voltage Change In Magnitude of Common-Mode Voltage Input High Voltage Input Low Voltage Input Hysteresis VOD 2.0 Figure 1, RL = 100Ω (automotive temperature range) 1.5 Figure 1, RL = 54Ω (RS-485) (extended temperature range) 1.5 V ∆VOD Figure 1, RL = 54Ω or 100Ω (Note 3) 0.2 V VOC Figure 1, RL = 54Ω or 100Ω 3 V ∆VOC Figure 1, RL = 54Ω or 100Ω (Note 3) 0.2 V VIH DE, DI, RE VIL DE, DI, RE VHYS DE, DI, RE Input Current (DE, DI, RE) IIN Driver Short-Circuit Output Current IOSD Driver Short-Circuit Foldback Output Current IOSDF 2 Figure 1, RL = 100Ω (RS-422) (extended temperature range) 2.0 V 0.8 50 ±1 0 < VIN < 5V 0 < VOUT < 12V (Note 4) +250 -7V < VOUT < VCC (Note 4) -250 (VCC - 1V) < VOUT < 12V (Note 4) +25 -7V < VOUT < 1V (Note 4) _______________________________________________________________________________________ V mV -25 µA mA mA 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package (VCC = +3.3V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Thermal Shutdown Threshold VTS 150 °C Thermal Shutdown Hysteresis VTSH 10 °C RECEIVER Receiver Differential Threshold Voltage VTH -7V < VCM < 12V -200 0 +200 mV Receiver Input Hysteresis ∆VTH V A + VB = 0 Receiver Output High Voltage VOH IO = -1mA, VA - VB = VTH Receiver Output Low Voltage VOL IO = 1mA, VA - VB = -VTH 0.4 V Three-State Output Current at Receiver IOZR 0 < VO < VCC ±1 µA Receiver Input Resistance RIN VCM = 12V Receiver Input Current Receiver Output Short-Circuit Current IIN IOSR 25 mV VCC - 0.4 V 96 DE = GND, VCC = GND or 3.465V kΩ VIN = +12V VIN = -7V 125 -100 µA ±150 mA 3.300 3.465 V 1.7 3 mA 1 10 µA 0 < VRO < VCC POWER SUPPLY Supply Voltage VCC Supply Current in Normal Operation (Static Condition) IQ Supply Current in Shutdown Mode ISHDN 3.135 No load, DI = VCC or GND DE = GND, RE = VCC SWITCHING CHARACTERISTICS (MAX3362E_ _ only) (VCC = +3.3V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 1) PARAMETER Driver Propagation Delay Driver Differential Output Rise or Fall Time SYMBOL tPDLH tPDHL tDR tDF CONDITIONS MIN TYP MAX 50 Figures 2 and 3, RL = 54Ω, CL = 50pF 50 12.5 Figures 2 and 3, RL = 54Ω, CL = 50pF 12.5 Figures 2 and 3, RL = 54Ω, CL = 50pF tDSKEW = |tPDLH - tPDHL| 6 UNITS ns ns ns Driver Output Skew tDSKEW Maximum Data Rate fMAX Driver Enable to Output Low tPDZL Figure 4, RL = 500Ω, CL = 50pF 100 ns Driver Disable Time from Low tPDLZ Figure 4, RL = 500Ω, CL = 50pF 100 ns Driver Disable Time from High tPDHZ Figure 5, RL = 500Ω, CL = 50pF 100 ns 20 Mbps _______________________________________________________________________________________ 3 MAX3362 DC ELECTRICAL CHARACTERISTICS (continued) MAX3362 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package SWITCHING CHARACTERISTICS (MAX3362E_ _ only) (continued) (VCC = +3.3V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 1) PARAMETER Driver Enable to Output High Receiver Propagation Delay Receiver Output Skew SYMBOL tPDZH tPRLH tPRHL tRSKEW CONDITIONS MIN TYP Figure 5, RL = 500Ω, CL = 50pF MAX UNITS 100 ns 50 Figure 6, CL = 15pF 50 Figure 6, CL = 15pF tRSKEW = |tPRLH - tPRHL| ns 6 ns Receiver Enable to Output Low tPRZL Figure 7, RL = 1kΩ, CL = 15pF 100 ns Receiver Enable to Output High tPRZH Figure 7, RL = 1kΩ, CL = 15pF 100 ns Receiver Disable Time from Low tPRLZ Figure 7, RL = 1kΩ, CL = 15pF 100 ns Receiver Disable Time from High tPRHZ Figure 7, RL = 1kΩ, CL = 15pF 100 ns 50 600 ns Time to Shutdown tSD (Note 5) Driver Enable from Output High to Shutdown tPDHS 50 600 ns Driver Enable from Output Low to Shutdown tPDLS 50 600 ns Receiver Enable from Output High to Shutdown tPRHS 50 600 ns Receiver Enable from Output Low to Shutdown tPRLS 50 600 ns Time to Normal Operation tNO (Note 6) 1500 3000 ns Driver Enable from Shutdown to Output High tPDSH Figure 5 RL = 500Ω, CL = 50pF 1500 3000 ns Driver Enable from Shutdown to Output Low tPDSL Figure 4 RL = 500Ω, CL = 50pF 1500 3000 ns Receiver Enable from Shutdown to Output High tPRSH Figure 7 RL = 1kΩ, CL = 15pF 1500 3000 ns Receiver Enable from Shutdown to Output Low tPRSL Figure 7 RL = 1kΩ, CL = 15pF 1500 3000 ns Note 1: Devices production tested at +25°C. Over-temperature limits are guaranteed by design. Note 2: All currents into the device are positive; all currents out of the device are negative. All voltages are referenced to device ground, unless otherwise noted. Note 3: ∆VOD and ∆VOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 4: 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. Note 5: Shutdown is enabled by bringing RE high and DE low. If the enable inputs are in this state for less than 50ns, the device is guaranteed not to enter shutdown. If the enable inputs are in this state for at least 600ns, the device is guaranteed to have entered shutdown. Note 6: Transition time from shutdown mode to normal operation. 4 _______________________________________________________________________________________ 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package 25 20 15 10 -15 -20 -25 5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 3.24 3.23 3.22 0 0.5 1.0 1.5 2.0 2.5 3.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 3.5 TEMPERATURE (°C) RECEIVER OUTPUT LOW VOLTAGE vs. TEMPERATURE DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE 0.01 0 45 30 15 2.2 2.4 2.6 2.8 3.0 DRIVER OUTPUT CURRENT vs. DRIVER OUTPUT HIGH VOLTAGE 4 5 6 7 8 9 10 11 12 DRIVER OUTPUT LOW VOLTAGE (V) 1.0 0.5 RL = 54Ω -40 -25 -10 5 20 35 50 65 80 95 110 125 SUPPLY CURRENT vs. TEMPERATURE 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 1.76 MAX3362 toc08 1.75 1.74 ICC (mA) MAX3362 toc07 3 DRIVER OUTPUT CURRENT (mA) DRIVER OUTPUT CURRENT vs. DRIVER OUTPUT LOW VOLTAGE 2 1.5 TEMPERATURE (°C) DIFFERENTIAL OUTPUT VOLTAGE (V) 1 2.0 3.4 3.2 TEMPERATURE (°C) 130 120 110 100 90 80 70 60 50 40 30 20 10 0 2.5 0 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 MAX3362 toc06 MAX3362 toc05 60 3.0 MAX3362 toc09 0.02 DRIVER OUTPUT CURRENT (mA) MAX3362 toc04 0.03 75 DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V) RECEIVER OUTPUT HIGH VOLTAGE (V) 0.04 0 3.25 RECEIVER OUTPUT LOW VOLTAGE (V) 0.05 DRIVER OUTPUT CURRENT (mA) 3.26 -30 0 RECEIVER OUTPUT LOW VOLTAGE (V) -10 RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE RECEIVER OUTPUT HIGH VOLTAGE (V) -5 OUTPUT CURRENT (mA) 30 MAX3362 toc02 35 OUTPUT CURRENT (mA) 0 MAX3362 toc01 40 OUTPUT CURRENT vs. RECEIVER OUTPUT HIGH VOLTAGE MAX3362 toc03 OUTPUT CURRENT vs. RECEIVER OUTPUT LOW VOLTAGE 1.73 1.72 1.71 1.70 1.69 1.68 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 DRIVER OUTPUT HIGH VOLTAGE (V) 4 5 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) _______________________________________________________________________________________ 5 MAX3362 Typical Operating Characteristics (VCC = +3.3V, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = +3.3V, TA = +25°C, unless otherwise noted.) 0.8 0.6 0.4 0.2 0 35 RECEIVER PROPAGATION DELAY (ns) 1.0 0.26 0.24 0.22 0.20 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0 MAX3362 toc11 1.2 DRIVER OUTPUT SKEW (ns) MAX3362 toc10 1.4 RECEIVER PROPAGATION DELAY vs. TEMPERATURE DRIVER OUTPUT SKEW vs. TEMPERATURE MAX3362 toc12 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE ISHDN (µA) 33 31 29 27 25 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) LOADED DRIVER OUTPUT WAVEFORM MAX3362 toc14 UNLOADED DRIVER OUTPUT WAVEFORM MAX3362 toc13 MAX3362 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package A 3.3V B 0 fDIN = 16Mbps A 2V B 0 20ns/div fDIN = 16Mbps RL = 54Ω 20ns/div RECEIVER PROPAGATION DELAY DRIVER PROPAGATION DELAY MAX3362 toc16 MAX3362 toc15 3.3V A 2V/div DIN 0 B RO A 2V/div 2V/div B fDIN = 16Mbps 6 20ns/div fDIN = 16Mbps 20ns/div _______________________________________________________________________________________ 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package PIN NAME DESCRIPTION 1 RO Receiver Output. RO is high if the receiver input differential (A-B) ≥ 200mV and the receiver is enabled (RE is low). RO is low if the receiver input differential (A-B) ≤ -200mV and the receiver is enabled. 2 RE Receiver Output Enable. Driving RE low enables RO. RO is high impedance when RE is high. Drive RE high and DE low (disable both receiver and driver outputs) to enter low-power shutdown mode. 3 DE Driver Output Enable. Driving DE high enables driver outputs. These outputs are high impedance when DE is low. Drive RE high and DE low (disable both receiver and driver outputs) to enter lowpower shutdown mode. 4 DI Driver Input. Driving DI low forces the noninverting output low and inverting output high, when the driver is enabled (DE is high). Driving DI high forces the noninverting output high and inverting output low. 5 GND 6 A Noninverting Receiver Input and Noninverting Driver Output 7 B Inverting Receiver Input and Inverting Driver Output 8 VCC Ground Supply Voltage. VCC = 3.3V ±5%. Bypass VCC to GND with a 0.1µF capacitor. RL/2 D D VOD RL/2 CL RL OUT VOC VCC VCC Figure 1. Driver DC Test Load CL = 50pF RL = 54Ω Figure 2. Driver Timing Test Circuit VCC VCC DI tfi tri tri = 5ns tfi = 5ns VCC /2 RL = 500Ω S1 0 0 or 3V tPDLH OUT D tPDHL CL = 50pF B (A+B)/2 A GENERATOR 50Ω 90% A-B 10% tDR VCC VCC/2 tDF IN 0 tPDSL, tPDZL Figure 3. Driver Propagation Delay tPDLZ OUT VCC VOM = (VOL + VCC) /2 VOL 0.25V Figure 4. Driver Enable and Disable Times (tPDSL, tPDZL, tPDLS, tPDLZ) _______________________________________________________________________________________ 7 MAX3362 Pin Description MAX3362 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package S1 0 or 3V OUT D RL = 500Ω CL = 50pF GENERATOR 50Ω VCC VCC/2 IN 0 tPDSH, tPDZH 0.25V VOM = (VOH) /2 VCC tPDHZ OUT VOL Figure 5. Driver Enable and Disable Times (tPDSH, tPDZH, tPDHS, tPDHZ) VID GENERATOR OUT R 50Ω CL = 15pF VOM = 1.5V VCC 2 0 3.0V IN OUT VOL 1.5V 1.5V tPRLH tPRHL VOM 0 VCC VOM 0 Figure 6. Receiver Propagation Delays 8 _______________________________________________________________________________________ 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package S3 S1 RL = 1kΩ VID -1.5V MAX3362 1.5V VCC R CL GENERATOR S2 50Ω 3V 3V 1.5V 1.5V IN 0 tPRZH tPRSH OUT IN 0 tPRZL tPRSL VOH VOC 1.5V OUT 0 S1 OPEN S2 CLOSED S3 = 1.5V VOL S1 CLOSED S2 OPEN S3 = -1.5V 3V 3V 1.5V 1.5V IN 0 tPRHZ IN 0 tPRLZ VOH 0.25V VOH OUT OUT 0 S1 OPEN S2 CLOSED S3 = 1.5V 0.25V 0 S1 CLOSED S2 OPEN S3 = -1.5V Figure 7. Receiver Enable and Disable Times Detailed Description The MAX3362 low-power, high-speed transceiver for RS-485/RS-422 communication operates from a single +3.3V power supply. The device contains one differential line driver and one differential line receiver. The driver and receiver may be independently enabled. When disabled, outputs enter a high-impedance state. The transceiver guarantees data rates up to 20Mbps, with an output skew of less than 6ns. This low skew time makes the MAX3362 ideal for multidrop clock/data distribution applications, such as cellular base stations. Driver and receiver propagation delays are below 50ns. The output level is guaranteed at 1.5V on a standard 54Ω load. The device has a hot-swap feature that eliminates false transitions on the data cable during circuit initialization. Also, drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry. _______________________________________________________________________________________ 9 MAX3362 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package Table 1. Transmitter Functional Table Drive RE high and DE low (disable both receiver and driver outputs) to enter low-power shutdown mode. TRANSMITTING INPUTS Hot-Swap Capability OUTPUTS RE DE DI A B X 1 1 1 0 X 1 0 0 1 0 0 X High Z 1 0 X High Z Shutdown Table 2. Receiver Functional Table RECEIVING INPUTS OUTPUT RE DE A–B RO 0 X ≥ 200mV 1 0 X ≤ -200mV 0 1 1 X High-Z 1 0 X Shutdown The MAX3362 has a 1/8-unit-load receiver input impedance, allowing up to 256 transceivers to be connected simultaneously on a bus. The MAX3362 is designed for half-duplex communication. Driver The driver transfers single-ended input (DI) to differential outputs (A, B). The driver enable (DE) input controls the driver. When DE is high, driver outputs are enabled. These outputs are high impedance when DE is low. When the driver is enabled, setting DI low forces the noninverting output (A) low and inverting output (B) high. Conversely, drive DI high to force noninverting output high and inverting output low (Table 1). Drive RE high and DE low (disable both receiver and driver outputs) to enter low-power shutdown mode. Receiver The receiver reads differential inputs from the bus lines (A, B) and transfers this data as a single-ended output (RO). The receiver enable (RE) input controls the receiver. Drive RE low to enable the receiver. Driving RE high places RO into a high-impedance state. When the receiver is enabled, RO is high if (A-B) ≥ 200mV. RO is low if (A-B) ≤ -200mV. 10 Hot-Swap Input When circuit boards are inserted into a hot or powered backplane, disturbances to the enable and differential receiver inputs can lead to data errors. Upon initial circuit board insertion, the processor undergoes its power-up sequence. During this period, the output drivers are high impedance and are unable to drive the DE input of the MAX3362 to a defined logic level. Leakage currents up to 10µA from the high-impedance output could cause DE to drift to an incorrect logic state. Additionally, parasitic circuit board capacitance could cause coupling of VCC or GND to DE. These factors could improperly enable the driver. When VCC rises, an internal pulldown circuit holds DE low for at least 10µs and until the current into DE exceeds 200µA. After the initial power-up sequence, the pulldown circuit becomes transparent, resetting the hot-swap tolerable input. Hot-Swap Input Circuitry The MAX3362 enable inputs feature hot-swap capability. At the input there are two NMOS devices, M1 and M2 (Figure 8). When VCC ramps from 0, an internal 10µs timer turns on M2 and sets the SR latch, which also turns on M1. Transistors M2, a 300µA current sink, and M1, a 30µA current sink, pull DE to GND through an 8kΩ resistor. M2 is designed to pull DE to the disabled state against an external parasitic capacitance up to 100pF that may drive DE high. After 10µs, the timer deactivates M2 while M1 remains on, holding DE low against threestate leakages that may drive DE high. M1 remains on until an external source overcomes the required input current. At this time, the SR latch resets and M1 turns off. When M1 turns off, DE reverts to a standard, highimpedance CMOS input. Whenever VCC drops below 1V, the hot-swap input is reset. For RE there is a complimentary circuit employing two PMOS devices pulling RE to VCC. Hot-Swap Line Transient The circuit of Figure 9 shows a typical offset termination used to guarantee a greater than 200mV offset when a line is not driven (the 50pF represents the minimum parasitic capacitance that would exist in a typical application). During a hot-swap event when the driver is ______________________________________________________________________________________ 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package MAX3362 VCC 10µs TIMER TIMER 8kΩ DE (HOT SWAP) DE 30µA M1 300µA M2 Figure 8. Simplified Structure of the Driver Enable Input (DE) 3.3V 3.3V 1kΩ VCC VCC 0 Y A TIN VCC OR GND 0.1kΩ 10mV/div AC-COUPLED 50pF B Z 1kΩ 10mV/div AC-COUPLED 10mV/div A-B 10µs/div Figure 9. Differential Power-Up Glitch (Hot Swap) Figure 10. Differential Power-Up Glitch (0.1V/µs) ______________________________________________________________________________________ 11 MAX3362 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package 3.3V 3.3V VCC 0 A 10mV/div AC-COUPLED B 10mV/div AC-COUPLED 10mV/div A-B 0 A 50mV/div AC-COUPLED B 50mV/div AC-COUPLED 10mV/div A-B 200ns/div 1µs/div Figure 11. Differential Power-Up Glitch (1V/µs) connected to the line and is powered up the driver must not cause the differential signal to drop below 200mV. Figures 10, 11, and 12 show the results of the MAX3362 during power-up for three different VCC ramp rates (0.1V/µs, 1V/µs, and 10V/µs). The photos show the VCC ramp, the single-ended signal on each side of the 100Ω termination, as well as the differential signal across the termination. Low-Power Shutdown Mode Low-power shutdown mode is initiated by bringing both RE high and DE low. In shutdown, the MAX3362 typically draws only 1µA supply current. RE and DE may be driven simultaneously; the device is guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the device will enter shutdown. Enable times t PDZH, t PDZL, t PRZH and t PRZL in the Switching Characteristics table assume the device was not in a low-power shutdown state. Enable times tPDSH, tPDSL, tPRSH, and tPRSL assume the device was shut down. Drivers and receivers take longer to become enabled from low-power shutdown mode than from driver/receiver disable mode. Applications Information Propagation Delays Figures 5 and 6 show the typical propagation delays. Skew time is simply the difference between the low-tohigh and high-to-low propagation delay. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle). Both the receiver skew time and driver skew time are under 6ns. 12 VCC Figure 12. Differential Power-Up Glitch (10V/µs) 256 Transceivers on the Bus The standard RS-485 receiver input impedance is 12kΩ (one-unit load), and a standard driver can drive up to 32 unit loads. The MAX3362 transceiver has a 1/8-unitload receiver input impedance (96kΩ), allowing up to 256 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 32 unit loads or less can be connected to the line. 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. Typical Applications The MAX3362 transceiver is designed for bidirectional data communications on multipoint bus transmission lines. The Typical Operating Circuit shows a typical network applications circuit. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. ______________________________________________________________________________________ 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package Functional Diagram VCC TOP VIEW DE RO 1 8 DI RE 2 DE MAX3362 VCC 7 B 3 6 A DI 4 5 GND D A MAX3362 B RD R RE SOT23 GND Chip Information TRANSISTOR COUNT: 708 PROCESS: BiCMOS ______________________________________________________________________________________ 13 MAX3362 Pin Configuration 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 www.maxim-ic.com/packages.) SOT23, 8L.EPS MAX3362 3.3V, High-Speed, RS-485/RS-422 Transceiver in SOT Package 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. 14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.