STC485E

STC485E ETC1 | Alldatasheet

Document overview

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Technical content

Features

ESD Protection for RS-485 I/O Pins ±15kV— Human Body Model ±15kV— IEC 1000-4-2, Air-Gap Discharge True Fail-Safe Receiver While Maintaining EIA/TIA-485 Compatibility Enhanced Slew-Rate Limiting Facilitates Error-Free Data Transmission 2nA Low-Current Shutdown Mode – 7V to +12V Common-Mode Input Voltage Range Allows up to 256 Transceivers on the Bus Thermal Shutdown Current-Limiting for Driver Overload Protection

Ordering Information

PART TEMP. RANGE PIN-PACKAGE STC485EESA -40°C to +85°C 8 SO STC485EEPA -40°C to +85°C 8 Plastic DIP PART NUMBER GUARANTEED DATA RATE (Mbps) Low- Power Shutdown SLEW-RATE LIMITED DRIVER/ RECEIVER ENABLE SHUTDOWN CURRENT (nA) Transceivers On Bus ±15kV ESD PROTECTION PIN COUNT STC485E 0.5 Yes Yes Yes 2 256 Yes 8

STC485E Datasheet Rev.0.1, Dec.2005 Page of 112 STC International Limited http://www.mcu-memory.com Absolute Maximum Ratings 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. (VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1) Note 1: All currents into the device are positive; all currents out of the device are negative. All voltages are referred to device ground unless otherwise noted. Note 2: VOD and VOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 3: Maximum current level applies to peak current just prior to foldback-current limiting; minimum current level applies during current limiting. PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DRIVER Differential Driver Output (No Load) VOD1 Figure 2 5 V Differential Driver Output VOD2 R= 50O, Figure 2 1.5 V Change in Magnitude of Driver Differential Output Voltage (Note 2) ? VOD R= 50O?, Figure 2 0.2 V Driver Common-Mode Output Voltage VOC R= 50O, Figure 2 3 V Change in Magnitude of Common -Mode Output Voltage (Note 2) ? VOC R= 50O, Figure 2 0.2 V Input High Voltage VIH DE, DI, /RE 2.0 V Input Low Voltage VIL DE, DI, /RE 0.8 V DI Input Hysteresis VHYS UM3085E 100 mV VIN = 12V 1.0 Input Current (A, B) IIN2 DE = 0V, VCC = 0V or 5V VIN = -7V -0.8 mA VOUT = -7V -250 Driver Short-Circuit Output Current (Note 3) IOSD VOUT = 12V 250 mA RECEIVER Receiver Differential Threshold Voltage VTH -7V=VCM=12V -0.2 -0.05 V Receiver Input Hysteresis ? VTH VCM = 0V 25 mV Receiver Output High Voltage VOH IOUT = -1.5mA, VID = 200mV VCC – 1.5 V Receiver Output Low Voltage VOL IOUT = 2.5mA, VID = 200mV 0.4 V Three-State (High Impedance) Output Current at Receiver IOZR VCC = 5V, 0V=VOUT\\=VCC ±1 µA Receiver Input Resistance RIN -7V=VCM=12V 96 kO? Receiver Short-Circuit Output Current IOSR 0V=VRO=VCC ±8 ±60 mA SUPPLY CURRENT DE = VCC, /RE = 0V or VCC 0.3 Supply Current ICC No load, DI = 0V or VCC DE = 0V, /RE = 0V 0.25 mA Supply Current in Shutdown Mode ISHDN DE = 0V, /RE = VCC, DI = VCC or 0V 0.002 10 µA Human Body Model ±15 ESD Protection for A, B IEC 1000-4-2 Air Discharge ±15 kV Control Input Voltage (/RE, DE) … … … … … … -0.3V to (V CC + 0.3V) Driver Input Voltage (DI) … … … … … … … … … -0.3V to (V CC + 0.3V) Driver Output Voltage (A, B) … … … … … … … … … … … -7.5V to 12.5V Receiver Input Voltage (A, B) … … … … … … … … … … … -7.5V to 12.5V Receiver Output Voltage (RO) … … … … … … … -0.3V to (V CC + 0.3V) Continuous Power Dissipation (TA = +70°C) 8-Pin Plastic DIP (derate 9.09mW/°C above +70°C… … … … 727mW 8-Pin SO (derate 5.88mW/°C above +70°… … … … … … … … 471mW Operating Temperature Ranges Storage Temperature Range … … … … … … … … … … -65°C to +160°C Lead Temperature (soldering, 10sec) … … … … … … … … … … +300°C

STC485E Datasheet Rev.0.1, Dec.2005 Page of 113 STC International Limited http://www.mcu-memory.com Switching Characteristics (VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS tDPLH 250 720 1000 Driver Input-to-Output tDPHL Figures 4 and 6, RDIFF = 54?, CL1 = CL2 = 100pF 250 720 1000 ns Driver Output Skew | tDPLH - tDPHL | tDSKEW Figures 4 and 6, RDIFF = 54?, CL1 = CL2 = 100pF -3 ±100 ns Driver Rise or Fall Time tDR, tDF Figures 4 and 6, RDIFF = 54?, CL1 = CL2 = 100pF 200 530 750 ns Maximum Data Rate fMAX 500 kbps Driver Enable to Output High tDZH Figures 5 and 7, CL = 100pF, S2 closed 2500 ns Driver Enable to Output Low tDZL Figures 5 and 7, CL = 100pF, S1 closed 2500 ns Driver Disable Time from Low tDLZ Figures 5 and 7, CL = 15pF, S1 closed 100 ns Driver Disable Time from High tDHZ Figures 5 and 7, CL = 15pF, S2 closed 100 ns Receiver Input to Output tRPLH, tRPHL Figures 11 and 13; | VID | =?2.0V; rise and fall time of VID =?15ns 127 200 ns | tRPLH - tRPHL | Differential Receiver Skew tRSKD Figures 8 and 10; | VID | =?2.0V; rise and fall time of VID =?15ns 3 3 ±30 ns Receiver Enable to Output Low tRZL Figures 3 and 9, CL = 100pF, S1 closed 20 50 ns Receiver Enable to Output High tRZH Figures 3 and 9, CL = 100pF, S2 closed 20 50 ns Receiver Disable Time from Low tRLZ Figures 3 and 9, CL = 100pF, S1 closed 20 50 ns Receiver Disable Time from High tRHZ Figures 3 and 9, CL = 100pF, S2 closed 20 50 ns Time to Shutdown tSHDN (Note 4) 50 200 600 ns Driver Enable from Shutdown-to-Output High tDZH(SHDN) Figures 5 and 7, CL = 15pF, S2 closed 4500 ns Driver Enable from Shutdown-to-Output Low tDZL(SHDN) Figures 5 and 7, CL = 15pF, S1 closed 4500 ns Receiver Enable from Shutdown-to-Output High tRZH(SHDN) Figures 3 and 9, CL = 100pF, S2 closed 3500 ns Receiver Enable from Shutdown-to-Output Low tRZL(SHDN) Figures 3 and 9, CL = 100pF, S1 closed 3500 ns

STC485E Datasheet Rev.0.1, Dec.2005 Page of 114 STC International Limited http://www.mcu-memory.com Typical Operating Characteristics (VCC = +5V, TA = +25°C, unless otherwise noted.) 525 500 475 450 425 400 375 350 325 300 -60-40-200 20 40 60 80 100 NO-LOAD SUPPLYCURRENT(uA) NO-LOAD SUPPLY CURRENT vs.TEMPERATURE OUTPUT CURRENT(mA) OUTPUT CURRENT vs.RECEIVER OUTPUT LOW VOLTAGE 0 1 2 3 4 5 OUTPUT LOW VOLTAGE（V） OUTPUT CURRENT(mA) OUTPUT CURRENT vs.RECEIVER OUTPUT HIGH VOLTAGE 0 1 2 3 4 5 OUTPUT HIGH VOLTAGE（V） TEMPERATURE（℃） SHUTDOWN CURRENT（nA） SHUTDOWN CURRENT vs.TEMPERATURE TEMPERATURE（℃） -60-40-200 20 40 60 80 100 OUTPUT LOW VOLTAGE（V） RECEIVER OUTPUT LOW VOLTAGE vs.TEMPERATURE 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 -60-40-200 20 40 60 80 100 TEMPERATURE（℃） OUTPUT VOLTAGE（V） RECEIVER OUTPUT HIGH VOLTAGE vs.TEMPERATURE 4.5 TEMPERATURE（℃） 4.4 4.3 4.2 4.1 4.0 3.9 3.8 -60-40-200 20 40 60 80 100 140 PROPAGATION DELAY（ns） RECEIVER PROPAGATION DELAY （500kbps MODE）vs.TEMPERATURE 135 130 125 120 115 TEMPERATURE（℃） -60-40-200 20 40 60 80 100 112 PROPAGATION DELAY（ns） RECEIVER PROPAGATION DELAY （10Mbps MODE）vs.TEMPERATURE TEMPERATURE（℃） 110 108 106 104 102 100 -60-40-200 20 40 60 80 100 -60-40-200 20 40 60 80 100 2.20 PROPAGATION DELAY（us） TEMPERATURE（℃） DRIVER PROPAGATION DELAY （115kbps MODE）vs.TEMPERATURE 2.15 2.10 2.05 2.00 1.95 1.90

STC485E Datasheet Rev.0.1, Dec.2005 Page of 115 STC International Limited http://www.mcu-memory.com Typical Operating Characteristics(continued) (VCC = +5V, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics(continued) (VCC = +5V, TA = +25°C, unless otherwise noted.) PROPAGATION DELAY（ns） DRIVER PROPAGATION DELAY （500kbps MODE）vs. TEMPERATURE TEMPERATURE（℃） 920 880 840 800 760 720 680 640 600 560 520 PROPAGATION DELAY（ns） DRIVER PROPAGATION DELAY （10Mbps MODE）vs.TEMPERATURE TEMPERATURE（℃） -60-40-200 20 40 60 80 100 -60-40-200 20 40 60 80 100 OUTPUT VOLTAGE（V） DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs.TEMPERATURE TEMPERATURE（℃） 1.90 1.89 1.88 1.87 1.86 1.85 1.84 1.83 -60-40-200 20 40 60 80 100 OUTPUT CURRENT（mA） DRIVER OUTPUT CURRENT vs.DIFFERENTIAL OUTPUT VOLTAGE 100 0.1 0.01 0 1 2 3 4 5 DIFFERENTIAL OUTPUT VOLTAGE（V） OUTPUT CURRENT（mA） OUTPUT CURRENT vs. DRIVER OUTPUT LOW VOLTAGE 140 OUTPUT LOW VOLTAGE（V） 120 100 0 2 4 6 8 10 12 OUTPUT CURRENT（mA） OUTPUT CURRENT vs. DRIVER OUTPUT HIGH VOLTAGE -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 -8 -6 -4 -2 0 2 4 6 OUTPUT HIGH VOLTAGE（V） RECEIVER PROPAGATION DELAY VA-VB RO 2V/div 5V/div 50ns/div VY-VZ DI 2.5V/div 5V/div 50ns/div DRIVER PROPAGATION DELAY

Table 1. Transmitting Table 2. Receiving Figure 1. STC485E / Pin Configuration and Typical Operating Circuit

0 X Inputs Open 1 Normal

1 RO Receiver Output. If A > B by -50mV, RO will be high; if A < B by 200mV, RO will be low. /RE is high and DE is low, the device will enter a low-power shutdown mode. function as line receivers if /RE is low.

5 GND Ground

6 A Noninverting Receiver Input and Noninverting Driver Output

7 B Inverting Receiver Input and Inverting Driver Output

8 VCC Positive Supply: VCC=5V±5%

STC485E Datasheet Rev.0.1, Dec.2005 Page of 117 STC International Limited http://www.mcu-memory.com Detailed Description The STC485E high-speed transceivers for RS-485 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 STC485E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 500kbps (see the Reduced EMI and Reflections section). All of these parts operate from a single +5V supply. Drivers 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. Fail-Safe The STC485E 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 threshold between – 50 mV and -200mV. If the differential receiver input voltage (A-B) is greater than or equal to -50mV, RO is logic high. If A-B is less than or equal to -200mV, RO is logic low. In the case of a terminated bus with all transmitters disabled, the receiver’s differential input voltage is pulled to 0V by the termination. With the receiver thresholds of the STC485E, , this results in a logic high with a 50mV minimum noise margin. Unlike previous fail-safe devices, the -50mV to -200mV threshold complies with the ±200 mV EIA/TIA-485 standard. ±15kV ESD Protection As with all STC devices, ESD-protection structures are incorporated on all pins to protect against electrostatic dis- charges encountered during handling and assembly. The driver outputs and receiver inputs of the STC485E have extra protection against static electricity. Union’s engineers have developed state-of-the-art structures to protect these pins against ESD of ±15kV without damage. The ESD-protected pins are tested with reference to the ground pin in a powered-down condition. They are tested to ±15kV using the Human Body Model. ESD Test Conditions ESD performance depends on a variety of conditions. Contact Union for a reliability report that documents test setup, test methodology, and test results. Human Body Model Machine Model The Machine Model for ESD tests all pins using a 200pF 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. All pins require this protecduring test and assembly. All pins require this protection, not just RS-485 inputs and outputs. Figure 11a shows the Human Body Model and Figure 11b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest which is then discharged into the test device through a 1.5k??resistor.

STC485E Datasheet Rev.0.1, Dec.2005 Page of 118 STC International Limited http://www.mcu-memory.com Applications Information

256 Transceivers on the Bus

Reduced EMI and Reflections The STC485E is slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 12 shows the same signal displayed for a STC485E, transmitting under the same conditions. In general, a transmitter’s rise time relates directly to the length of an unterminated stub, which can be driven with only minor waveform reflections. The following equation expresses this relationship conservatively: Length = tRISE / (10 x 1.5ns/ft) where tRISE is the transmitter’s rise time. A system can work well with longer unterminated stubs, even with severe reflections, if the waveform settles out before the UART samples them. Low-Power Shutdown Mode Low-power shutdown mode is initiated by bringing both /RE high and DE low. In shutdown, the devices typically draw only 2 nA of supply current. /RE and DE may be driven simultaneously; the parts are 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 parts are guaran -teed to enter shutdown. Enable times tZH and tZL in the Switching Characteristics tables assume the part was not in a low-power shutdown state. Enable times tZH(SHDN) and tZL(SHDN) assume the parts were shut down. It takes drivers and receivers longer to become enabled from low-power shutdown mode (tZH(SHDN), tZH(SHDN)) than from driver/receiver -disable mode (tZH, tZL). 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. Line Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, repeater is required. Typical Applications The STC485E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 14 show typical network applications circuits. 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. The standard RS-485 receiver input impedance is 12k O? (one-unit load), and the standard driver can drive up to 32 unit loads. The STC family of trans -ceivers have a 1/8-unit-load receiver input impe -dance (96kO), 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.

STC485E Datasheet Rev.0.1, Dec.2005 Page of 1111 STC International Limited http://www.mcu-memory.com

Package Information

A D e B E H C L 0°- 8° 0.101mm 0.004in. SO SMALL OUTLINE PACKAGE （0.150in.） DIM INCHES MILLIMETERS MIN MAX MIN MAX A 0.0530.069 1.35 1.75 A1 0.0040.010 0.10 0.25 B 0.0140.019 0.35 0.49 C 0.0070.010 0.19 0.25 E 0.1500.157 3.80 4.00 e 0.050 1.27 H 0.2280.244 5.80 6.20 L 0.0160.050 0.40 1.27 DIMPINS INCHES MILLIMETERS MIN MAX MIN MAX D 8 0.1890.1974.805.00 D 14 0.3370.3448.558.75 D 16 0.3860.3949.8010.00 21-0041A DIM INCHES MILLIMETERS MIN MAX MIN MAX A - 0.200 - 5.08 A1 0.015 - 0.38 - A2 0.1250.1753.18 4.45 A3 0.0550.0801.40 2.03 B 0.0160.0220.41 0.56 B1 0.0450.0651.14 1.65 C 0.0080.0120.20 0.30 D1 0.0050.0800.13 2.03 E 0.3000.3257.62 8.26 E1 0.2400.3106.10 7.87 e 0.100 - 2.54 - eA 0.300 - 7.62 - eB - 0.400 - 10.16 L 0.1150.1502.92 3.81 Plastic DIP PLASTIC DUAL-IN-LINE PACKAGE (0.300in.) DIM PIN INCHES MILLIMETERS MIN MAX MIN MAX D 8 0.3480.3908.849.91 D 14 0.7350.76518.6719.43 D 16 0.7450.76518.9219.43 D 18 0.8850.91522.4823.24 D 20 1.0151.04525.7826.54 D 24 1.141.26528.9632.13 D A L B e E eA eB C 0°- 15°