MAX3485ESA+T

MAX3485ESA+T FEATURES ➢ 3.0V~5.5V Wide Power Range, Half-Duplex ➢ ESD Protection for RS-485 I/O Pins ±15kV, Human Body Model ➢ Bus Fault Tolerance and Withstand Voltage Reach ±15V ➢ 1/8 Unit Load，Allow Up to 256 Transceivers on the Bus ➢ Driver Short-Circuit Output Protection ➢ Low Power Off Function ➢ Receiver Open-Circuit Failure Protection ➢ Strong Anti-Noise Ability ➢ Integrated Transient Voltage Suppression Function ➢ Data transmission up to 12Mbps in an electric noise SOP-8 SOP-8 environment DESCRIPTION MAX3485 is a RS-485 transceiver with 3.0V~5.5V wide power supply, bus port ESD protection capacity of over 15kV HBM, bus withstand voltage range of ±15V, half duplex, low power consumption, and fully meet the requirements of TIA / EIA-485 standard. MAX3485 includes a driver and a receiver, both of which can be enabled and closed independently. When both are disabled, both the driver and the receiver output are high resistance state. MAX3485 has 1/8 load, which allows 256 MAX3485 transceivers to be connected to the same communication bus. It can realize error-free data transmission up to 12Mbps. MAX3485 has a working voltage range of 3.0~5.5V, and has the functions of fail safe, over temperature protection, current-limiting protection, over-voltage protection, etc. PIN CONFIGURATION RO R VCC RE B DE A DI Figure 1 D GND MAX3485 Configuration E PinPin Configuration www.tokmas.com MAX3485ESA+T LIMITING VALUES PARAMETER SYMBOL VALUE UNIT Supply voltage VCC +7 V Control Input Voltage /RE，DE，DI -0.3~VCC+0.5 V Receiver Input Voltage A，B -15~+15 V Receiver Output Voltage RO -0.3~VCC+0.5 V Operating Temperature Ranges -40~125 ℃ Storage Temperature Range -60~150 ℃ Lead Temperature 300 ℃ SOP8 470 mW MSOP8 830 mW DIP8 700 mW Continuous Power Dissipation The maximum limit parameters means that exceeding these values may cause irreversible damage to the device. Under these conditions, it is not conducive to the normal opration of the device. The continuous operation of the device at the maximum allowable rating may affect the reliability of the device. The reference point for all voltages is ground. PINNING PIN SYMBOL DESCRIPTION 1 RO Receiver Output. When /RE is low and if A - B≥-10mV, RO will be high; if A - B≤-200mV, RO will be low. /RE Receiver Output Enable. Drive /RE low to enable RO; RO is high impedance when /RE is high. Drive /RE high and DE low to enter low-power shutdown mode. DE Driver Output Enable. Drive DE high to enable driver outputs. These outputs are high impedance when DE is low. Drive /RE high and DE low to enter low-power shutdown mode. 4 DI Driver Input. With DE high, a low on DI forces non-inverting output low and inverting output high. Similarly, a high on DI forces non-inverting output high and inverting output low. 5 GND 6 A non-inverting Receiver Input and non-inverting Driver Output 7 B Inverting Receiver Input and Inverting Driver Output 8 VCC 2 3 Ground Positive Supply www.tokmas.com MAX3485ESA+T DRIVER DC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL Differential Driver Output（No load） CONDITION MIN. MAX. UNIT 3 5.5 V Figure 2，RL = 54 Ω， VCC=3.3V 1.5 VCC Figure 2，RL = 54 Ω， VCC=5V 1.5 VOD1 TYP. Differential Driver Output VOD2 Change in Magnitude of Driver Differential Output Voltag（NOTE1） ∆VOD Figure 2，RL = 54 Ω 0.2 V Driver Common-Mode Output Voltage VOC Figure 2，RL = 54 Ω 3 V Change in Magnitude of Common-Mode Output Voltage（NOTE1） ∆VOC Figure 2，RL = 54 Ω 0.2 V Input High Voltage VIH DE，DI，/RE Input Low Voltage VIL DE，DI，/RE Logic Input Current IIN1 DE，DI，/RE Output short-circuit current, short-circuit to high IOSD1 short-circuit to 0V~12V Output short-circuit current, short-circuit to low IOSD2 short-circuit to -7V~0V V VCC 2.0 V -2 0.8 V 2 μA 250 mA mA -250 （Unless otherwise noted，Temp=TMIN~TMAX， Temp＝25℃） NOTE1：∆VOD and ∆VOC are the changes in VOD and VOC, respectively, when the DI input changes state. RECEIVER DC ELECTRICAL CHARACTERISTICS PARAMETER Input current（A，B） SYMBOL IIN2 CONDITION MIN. DE = 0 V， VCC=0 或 3.3/5V VIN = 12 V DE = 0 V， VCC=0 或 3.3/5V VIN = -7 V -100 www.tokmas.com TYP. MAX. UNIT 125 μA μA MAX3485ESA+T Positive input threshold voltage VIT+ -7V≦VCM≦12V Reverse input threshold voltage VIT- -7V≦VCM≦12V -200 Input hysteresis voltage Vhys -7V≦VCM≦12V 10 Receiver Output High Voltage VOH IOUT = −2.5mA， VID = +200 mV VCC-1.5 Receiver Output Low Voltage VOL IOUT = +2.5mA， VID = -200 mV 0.4 V Three-State Output Current at Receiver IOZR 0.4 V < VO < 2.4 V ±1 μA Receiver Input Resistance RIN -7V≦VCM≦12V 96 Receiver Short-Circuit Output Current IOSR 0 V≤VO≤VCC ±8 -10 mV mV 30 mV V kΩ ±90 mA TYP. MAX. UNIT /RE=0V， DE = 0 V， VCC=3.3V 240 650 μA /RE=0V， DE = 0 V VCC=5V 270 750 μA /RE=VCC， DE=VCC， VCC=3.3V 250 650 μA /RE=VCC， DE=VCC， VCC=5V 280 750 μA /RE=VCC， DE=0V， VCC=3.3V 0.2 10 μA /RE=VCC， DE=0V， VCC=5V 0.2 10 μA （Unless otherwise noted， Temp=TMIN~TMAX，Temp＝25℃） SUPPLY CURRENT PARAMETER SYMBOL ICC1 Supply Current ICC2 Shutdown current ISHDN CONDITION MIN. www.tokmas.com MAX3485ESA+T DRIVER SWITCHING CHARACTERISTICS PARAMETER SYMBOL Driver differential Output delay tDD Driver differential output Transition time tTD Drive propagation delay From low to high tPLH CONDITION MIN. RL = 60 Ω, CL1=CL2=100pF (figure3、4) RL = 27 Ω, (figure3、4) TYP. MAX. UNIT 20 40 ns 12 28 ns 20 40 ns 20 40 ns 1 8 ns 55 ns 55 ns 85 ns 85 ns Drive propagation delay From high to low tPHL |tPLH-tPHL| tPDS Driver Enable to Output High tPZH Driver Enable to Output low tPZL Driver Disable Time from Low tPLZ Driver Disable Time from high tPHZ In Shutdown mode， Enable to Output High tDSH RL = 110Ω， （figure 5、6） 20 100 ns In Shutdown mode， Enable to Output low tDSL RL = 110Ω， （figure 5、6） 20 100 ns RL = 110Ω， （figure5、6） RL = 110Ω， （figure 5、6） RECEIVER SWITCHING CHARACTERISTICS PARAMETER SYMBOL Receiver Input to output from low to high tRPLH Receiver Input to output from high to low tRPHL CONDITION MIN. TYP. MAX. UNIT 60 ns 60 ns CL=15pF Figure7 & Figure8 www.tokmas.com MAX3485ESA+T |tRPLH − tRPHL| tRPDS 3 10 ns Receiver Enable to Output Low tRPZL CL=15pF Figure7& Figure 8 15 40 ns Receiver Enable to Output high tRPZH CL=15pF Figure7 & Figure8 15 40 ns Receiver Disable Time from Low tPRLZ CL=15pF Figure7 & Figure8 25 55 ns Receiver Disable Time from high tPRHZ CL=15pF Figure7 & Figure8 25 55 ns In Shutdown mode， Enable to Output High tRPSH CL=15pF Figure7 & Figure8 150 500 ns In Shutdown mode， Enable to Output low tRPSL CL=15pF Figure7 & Figure8 150 500 ns Time to Shutdown tSHDN NOTE2 300 ns 50 NOTE2： If the enable inputs are RE=high and DE=low for less than 50ns, the device is guaranteed not to enter shutdown. If the enable inputs are in this state for at least 300ns, the device is guaranteed to have entered shutdown. FUNCTION TABLE Driver Function CONTROL INPUT Receiver Function OUTPUT CONTROL INPUT OUTPUT /RE DE DI A B /RE DE A-B RO X 1 1 H L 0 X ≥-10mV H X 1 0 L H 0 X ≤-200mV L 0 0 X Z Z 0 X Open/short circuit H 1 0 X Z(shutdown) 1 X X Z X=irrelevant; Z=high impedance X=irrelevant; Z=high impedance www.tokmas.com MAX3485ESA+T TEST CIRCUIT Figure 2 Driver DC test load CL includes probe and stray capacitance (the same below) Figure 3 Differential delay and transit time of driver Figure 4 Drive propagation delay www.tokmas.com MAX3485ESA+T Figure 5 Drive enable and disable time Figure 6 Drive enable and disable time Figure 7 Receiver propagation delay test circuit www.tokmas.com MAX3485ESA+T Figure 8 Receiver enable and disable time www.tokmas.com MAX3485ESA+T ADDITIONAL DESCRIPTION 1 Sketch MAX3485E is a half-duplex high-speed transceiver with 3.0V~5.5V wide power supply, bus port ESD protection capacity of more than 15kV HBM, bus DC withstand voltage of more than ±15V, used for RS-485/RS-422 communication, including a driver and receiver. It has the functions of fail-safe, over-voltage protection, over-current protection and over temperature protection MAX3485E realizes error-free data transmission up to 12Mbps. 2 Allowing up to 256 Transceivers on the Bus The input impedance of the standard RS485 receiver is 12kΩ (1 unit load), and the standard driver can drive up to 32 unit loads. The receiver of MAX3485E transceiver has 1/8 unit load input impedance (96kΩ), which allows up to 256 transceivers to be connected on the same communication bus in parallel. These devices can be combined arbitrarily or with other RS485 transceivers.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. 3 Driver output protection Tow mechanisms prevent excessive output current and power dissipation caused by faults or by bus contention.First, over-current protection,fast short circuit protection in the mode voltage range (refer to typical operating characteristics). Second, when the temperature of the tube core exceeds 140℃, the output of the driver is forced into the high resistance state. 4 Typical Applications 4.1Bus Networking: MAX3485E RS485 transceiver is designed for bidirectional data communication on multi-point bus transmission line. Figure 9 shows a typical network application circuit. These devices can also be used as linear repeaters with cables longer than 4000 feet. In order to reduce reflection, terminal matching should be carried out at both ends of the transmission line with its characteristic impedance, and the length of branch lines outside the main line should be as short as possible. MAX3485E 120Ω RE VCC B DE A RO DI R VCC B VCC B A GND VCC B DE D Slave 2 RE RO DI DE RE RO DI DE Figure 9 Bus type RS485 half duplex communication network www.tokmas.com RO RE Slave N MAX3485E R D MAX3485E R D Slave 1 A GND Master R A GND GND D MAX3485E 120Ω DI MAX3485ESA+T 4.2 Hand in hand Networking: also known as daisy chain topology, is the standard and specification of RS485 bus wiring, and is the RS485 bus topology recommended by TIA and other organizations. The wiring mode is that the main control equipment and a plurality of slave control equipment form a hand-held connection mode, as shown in Figure 10, and the hand-held mode is no branches. This wiring mode has the advantages of small signal reflection and high communication success rate. DI MAX3485E A VCC B RO R RE A GND D MAX3485E 120Ω VCC B DE A GND RE R R D 120Ω VCC B RO RO RE DI DE MAX3485E R D MAX3485E VCC B A GND R D Slave1 MAX3485E Master VCC B A GND GND DE DI D Slave N Slave 2 RE RO DI DE RE RO DI DE Figure10 Hand in hand RS485 half duplex communication network 4.3 Bus port protection: in severe environment, RS485 communication port is usually provided with electrostatic protection, lightning surge protection and other additional protection, and even the plan to prevent 380V market electricity access is needed to avoid the damage of intelligent instrument and industrial control host. Figure 11 shows three common RS485 bus port protection schemes. The first is the scheme of three-level protection by connecting TVS devices in parallel with A,B port to the protective ground, TVS devices in parallel with A,B port, thermistor in series with A,B port, gas discharge tube in parallel to the protective ground; the second is the scheme of three-level protection by connecting TVS in parallel with A,B port to the ground, thermistor in series with A,B port, and varistor in parallel with A,B port; the third is the scheme of three-level protection by connecting AB with pull-up or pull-down resistor to power and ground respectively, connecting TVS between A & B, A or B port connecting thermistor. MAX3485E PTC1 RE VCC B DE A RO DI R TVS1 GDT TVS3 GND D TVS2 Master or Slave PTC2 PE MAX3485E MAX3485E TVS1 VCC B DE A DI R D Master or Slave RO PTC1 R RE CK RE RO GND PTC1 TVS2 VCC B A DE DI D GND Master or Slave Figure 11 Port protection scheme www.tokmas.com PTC1 TVS1 MAX3485ESA+T SOP8 DIMENSIONS PACKAGE SIZE SYMBOL MIN./mm TYP./mm MAX./mm A 1.40 - 1.80 A1 0.10 - 0.25 A2 1.30 1.40 1.50 b 0.38 - 0.51 D 4.80 4.90 5.00 E 3.80 3.90 4.00 E1 5.80 6.00 6.20 e 1.27BSC L 0.40 0.60 0.80 c 0.20 - 0.25 θ 0° - 8° www.tokmas.com MAX3485ESA+T MSOP8 /8μMAX / VSSOP8 DIMENSIONS PACKAGE SIZE SYMBOL MIN./mm TYP./mm MAX./mm A 2.90 3.0 3.10 A1 0.28 0.35 A2 0.65TYP A3 0.375TYP B 2.90 3.0 B1 4.70 5.10 B2 0.45 0.75 C 0.75 0.95 C1 3.10 1.10 C2 0.328 TYP C3 0.152 C4 0.15 0.23 H 0.00 0.09 θ 12°TYP www.tokmas.com MAX3485ESA+T DIP8 DIMENSIONS Package size SYMBOL MIN./mm TYP./mm MAX./mm A 9.00 9.20 9.40 A1 0.33 0.45 0.51 A2 2.54TYP A3 1.525TYP B 8.40 8.70 9.10 B1 6.20 6.40 6.60 B2 7.32 7.62 7.92 C 3.20 3.40 3.60 C1 0.50 0.60 0.80 C2 3.71 4.00 4.31 D 0.20 0.28 0.36 L 3.00 3.30 3.60 ORDERING INFORMATION TYPE NUMBER TEMPERATURE PACKAGE MAX3485ESA+T -40℃~125℃ SOP8 MAX3485EEUA -40℃~125℃ MSOP8/VSSOP8/8μMAX MAX3485EEPA -40℃~125℃ DIP8 Tapered package is 2500 pcs/reel. The HVSON8/DFN3*3-8 package is 5000 pcs/reel. www.tokmas.com