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Technical content
Features
RS-422 Communications Level Translators Transceivers for EMI-Sensitive
Applications
Industrial-Control Local Area Networks ESD Protection for RS-422 I/O Pins ±15kV, Human Body Model True Fail-Safe Receiver While Maintaining EIA/TIA-422 Compatibility Enhanced Slew-Rate Limiting Facilitates Error-Free Data Transmission 1nA Low-Current Shutdown Mode (UM491) Allow Up to 256 Transceivers on the Bus Selector Guide Part Number Half/Full Duplex Data Rate (Mbps) Slew- Rate Limited Low- Power Shutdown Receiver/ Driver Enable Quiescent Current (µA) Transceivers On Bus Pin Count UM488 full 2.5 Yes No No 375 256 8 UM491 full 2.5 Yes Yes Yes 375 256 14
Ordering Information
Part Number Temperature Range P ackaging Type Shipping Qty UM488EESA -40°C to +85°C SOP8 2500pcs/13 Inch Tape & Reel UM488EEPA -40°C to +85°C DIP8 50pcs/Tube UM491EESE -40°C to +85°C SOP14 2500pcs/13 Inch Tape & Reel UM491EEPE -40°C to +85°C DIP14 50pcs/Tube
http://www.union-ic.com Rev.04 Aug.2013 2 / 1 7 UM488/UM491 P i n C o n f i g u r a t i o n s T o p V i e w XX: Week Code UM491EESE SOP14 XX: Week Code UM491EEPE DIP14 XX: Week Code UM488EESA SOP8 XX: Week Code UM488EEPA DIP8 Absolute Maximum Ratings Symbol Parameter Value Unit VCC Supply Voltage +7 V Control Input Voltage (RE , DE) -0.3V to (VCC + 0.3V) V Driver Input Voltage (DI) -0.3V to (VCC + 0.3V) V Driver Output Voltage (A, B, Y, Z) ±13 V Receiver Input Voltage (A, B) ±25 V Receiver Output Voltage (RO) -0.3V to (VCC + 0.3V) V PD 8-Pin SO (derate 9.09mW/°C above +70°C) 520 mW 8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) 727 14-Pin Plastic DIP (derate 10.0mW/°C above +70°C) 800 14-Pin SO (derate 8.33mW/°C above +70°C) 667 TA Ambient Temperature -40 to +85 °C TSTG Storage Temperature Range -65 to +150 °C TL Lead Temperature for Sold ering 10 seconds +300 °C 7 8 R D NC RO RE DE DI GND GND VCC NC A B Z Y NC
http://www.union-ic.com Rev.04 Aug.2013 3 / 1 7 UM488/UM491 (VCC = +5V ± 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1) Parameter Symbol Test Conditions Min Typ Max Unit DRIVER Differential Driver Output (No Load) VOD1 Figure 3 5 V Differential Driver Output VOD2 Figure 3, R = 50Ω 2.0 V Change-in-Magnitude of Differential Output Voltage (Note 2) ΔVOD Figure 3, R = 50Ω 0.2 V Driver Common-Mode Output Voltage VOC Figure 3, R = 50Ω 3.0 V Change-in-Magnitude of Common-Mode Voltage (Note 2) ΔVOC Figure 3, R = 50Ω 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 100 mV Input Current (A and B) IIN DE = GND, VCC = GND or 5.25V VIN = 12V 125 µA VIN = -7V -75 Output Leakage (Y and Z) I O DE = GND, VCC = GND or 5.25V VIN = 12V 125 µA VIN = -7V -100 Driver Short-Circuit Output Current (Note 3) VOD1 -7V≤VOUT≤VCC -250 mA0V≤VOUT≤12V 250 0V≤VOUT≤VCC ±25
http://www.union-ic.com Rev.04 Aug.2013 4 / 1 7 UM488/UM491 (VCC = +5V ± 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1) Parameter Symbol Test Conditions Min Typ Max Unit RECEIVER Receiver Differential Threshold Voltage VTH -7V≤VCM≤12V -200 -125 -50 mV Receiver Input Hysteresis Δ VTH 25 mV Receiver Output High Voltage VOH IO = -4mA, VID = -50mV VCC -1.5 V Receiver Output Low Voltage VOL IO = 4mA, VID = -200mV 0.4 V Three-State Output Current at Receiver IOZR 0.4V ≤ VO ≤ 2.4V ±1 µA Receiver Input Resistance RIN -7V≤VCM≤12V 96 K Ω Receiver Output Short Circuit Current IOSR 0V≤VRO ≤VCC ±7 ±95 mA SUPPLY CURRENT Supply Current ICC No load, RE = DI = GND or VCC DE = VCC 430 900 µA DE = GND 375 600 Supply Current in Shutdown Mode ISHDN DE = GND, V RE = VCC 0.001 10 µA ESD Protection for Y, Z, A, B Human Body Model ±15 kV 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: ΔVOD and ΔVOC are the changes in V OD and V OC, 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.
http://www.union-ic.com Rev.04 Aug.2013 5 / 1 7 UM488/UM491 Switching Characteristics (VCC = +5V ± 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) Parameter Symbol Test Conditions Min Typ Max Unit Driver Input-to-Output tDPLH Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF 10 30 60 ns tDPHL 10 30 60 Driver Output Skew | tDPLH - tDPHL | tDSKEW Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF 5 10 ns Driver Rise or Fall Time tDR, tDF Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF 5 15 25 ns Maximum Data Rate fMAX 2.5 Mbps Driver Enable to Output High tDZH Figures 6 and 8, CL = 100pF, S2 closed 40 70 ns Driver Enable to Output Low tDZL Figures 6 and 8, CL = 100pF, S1 closed 40 70 ns Driver Disable Time from Low tDLZ Figures 6 and 8, CL = 15pF, S1 closed 40 70 ns Driver Disable Time from High tDHZ Figures 6 and 8, CL = 15pF, S2 closed 40 70 ns Receiver Input to Output tRPLH, tRPHL Figures 9 and 11; | VID | ≥2.0V; rise and fall time of VID≤15ns 20 90 150 ns | tRPLH - tRPHL | Differential Receiver Skew tRSKD Figures 9 and 11; | VID | ≥2.0V; rise and fall time of VID≤15ns 13 ns Receiver Enable to Output Low tRZL Figures 4 and 10, CL = 100pF, S1 closed 20 50 ns Receiver Enable to Output High tRZH Figures 4 and 10, CL = 100pF, S2 closed 20 50 ns Receiver Disable Time from Low tRLZ Figures 4 and 10, CL = 100pF, S1 closed 20 50 ns Receiver Disable Time from High tRHZ Figures 4 and 10, 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 6 and 8, CL = 15pF, S2 closed 40 100 ns Driver Enable from Shutdown to Output Low tDZL(SHDN) Figures 6 and 8, CL = 15pF, S1 closed 40 100 ns Receiver Enable from Shutdown- to-Output High tRZH(SHDN) Figures 4 and 10, CL = 100pF, S2 closed 300 1000 ns Receiver Enable from Shutdown- to-Output Low tRZL(SHDN) Figures 4 and 10, CL = 100pF, S1 closed 300 1000 ns Note 4: The device is put into shutdown 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.
http://www.union-ic.com Rev.04 Aug.2013 6 / 1 7 UM488/UM491 Typical Operating Characteristics (VCC = +5V, TA = +25°C, unless otherwise noted.) Output Current vs. Receiver Output High Voltage 0123456 Output High Voltage (V) Output Current (μA) Output Current vs. Receiver Output Low Voltage 0123456 Output Low Voltage (V) Output Current (μA) Receiver Output High Voltage vs. Temperature 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 -60 -40 -20 0 20 40 60 80 100 Temperature( ℃) Receiver Output High Voltage(V) IRO=8mA No Load Supply Current vs. Temperature 200 225 250 275 300 325 350 375 400 -60 -40 -20 0 20 40 60 80 100 Temperature( ℃) No Load Supply Current(uA) RE=L,DE=H
http://www.union-ic.com Rev.04 Aug.2013 7 / 1 7 UM488/UM491 Typical Operating Characteristics (Continued) (VCC = +5V, TA = +25°C, unless otherwise noted.) Receiver Output Low Voltage vs. Temperature 0.1 0.15 0.2 0.25 0.3 0.35 0.4 -60 -40 -20 0 20 40 60 80 100 Temperature( ℃) Receiver Output Low Voltage(V) Driver Differential Output Voltage vs. Temperature 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 -60 -40 -20 0 20 40 60 80 100 Temperature( ℃) Output Voltage(V) Driver Output Current vs. Differential Output Voltage 0.1 100 0123456 Differential Output Voltage (V) Output Current (mA) IRO=8mA RT=54ohm
http://www.union-ic.com Rev.04 Aug.2013 8 / 1 7 UM488/UM491 Pin Description Symbol Pin Number Function UM488 UM491 NC - 1 Not Connected RO 2 2 Receiver Output. When R E is low and if A - B ≥-50mV, RO will be high; if A - B ≤ -200mV, RO will be low. RE - 3 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 - 4 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. DI 3 5 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. GND 4 6 Ground GND 4 7 Ground NC - 8 Not Connected Y 5 9 Non-inverting Driver Output Z 6 10 Inverting Driver Output B 7 11 Inverting Receiver Input A 8 12 Non-inverting Receiver Input NC - 13 Not Connected VCC 1 14 Positive Supply 4.75V ≤ VCC≤ 5.25V Functions Tables TRANSMITTING INPUTS OUTPUTS RE DE DI Z Y X 1 1 0 1 X 1 0 1 0 0 0 X High-Z High-Z 1 0 X Shutdown RECEIVING INPUTS OUTPUT RE DE A-B RO 0 X ≥-0.05V 1 0 X ≤-0.2V 0
0 X Open/Short 1
http://www.union-ic.com Rev.04 Aug.2013 1 0 / 1 7 UM488/UM491 Detailed Description The UM488/UM491 high-speed transceivers for RS -422 communication contain one driver and one receiver. The device features 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. The UM488/UM491 offer higher driver output slew-ra te limits, allowing transmit speeds up to 2.5Mbps. The UM488/UM491 is full-duplex transceiver. It operates from a single +5V supply. Drivers are output short-circuit current limited. Thermal shut down circuitry protects drivers against excessive power dissipation. When activated, the thermal s hutdown circuitry places the driver outputs into a high- impedance state. Receiver Input Filtering The receivers of the UM488/UM491 incorporate input filtering in addition to input hysteresis. This filtering enhances noise immunity with differe ntial signals that have very slow rise and fall times. Receiver propagation delay increases by 20% due to this filtering. Fail-Safe The UM488/UM491 guarantees a logic-high receiver output when the receiver inputs are shorted or open, or when they are connected to a termin ated transmission line with all drivers disabled. This is done by setting the receiver threshold between -50mV and -200mV. If the differential receiver input voltage (A-B) is greater than or e qual 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 UM488/UM491, 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 ±200mV EIA/TIA-422 standard. ±15kV ESD Protection As with all Union devices, ESD-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 UM488/UM491 have extra protection against static electricity. Union’s engineers have developed state-of-the-art struct ures to protect these pins against ESD of ±15kV without damage. The ESD-protected pins are test ed with reference to the ground pin in a powered-down condition. They are tested to ±15kV using the Human Body Model.
http://www.union-ic.com Rev.04 Aug.2013 1 2 / 1 7 UM488/UM491 Applications Information
256 Transceivers on the Bus
The standard RS-422 receiver input impedance is 12k Ω (one-unit load), and the standard driver can drive up to 32 unit loads. The UM491 has a 1/8-unit-load receiver input impedance (96k Ω), allowing up to 256 transceivers to be connect ed in parallel on one communication line. Any combination of these devices and/or other RS-422 tr ansceivers with a total of 32 unit loads or less can be connected to the line. Reduced EMI and Reflections The UM488/UM491 is slew-rate limited, minimi zing EMI and reducing reflections caused by improperly terminated cables. It’s high-freque ncy harmonic components are much lower in amplitude, and the potential for EMI is significantly reduced. In general, a transmitter’s rise time relates direc tly to the length of an unterminated stub, which can be driven with only minor waveform reflections. The following equation expresses this relationship conservatively: Length = t RISE / (10 × 1.5ns/ft) where tRISE is the transmitter’s rise time. Low-Power Shutdown Mode (UM491) Low-power shutdown mode is initiated by bringing both RE high and DE low. In shutdown, the devices typically draw only 1nA 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 guaranteed to enter shutdown. Enable times t ZH and t ZL in the Switching Characteristics tables assume the part was not in a low-power shutdown state. Enable times t ZH(SHDN) and t ZL(SHDN) assume the parts were shut down. It takes drivers and receivers longer to become enabled from low-power shutdown mode (t ZH(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 whol e common-mode voltage range. The second, a ther- mal shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature becomes excessive. Line Length vs. Data Rate The RS-422 standard covers line lengths up to 400 0 feet. For line lengths greater than 4000 feet, use the repeater application shown in Figure 12.
http://www.union-ic.com Rev.04 Aug.2013 1 3 / 1 7 UM488/UM491
Package Information
A 1.350 1.750 0.053 0.069 A1 0.100 0.250 0.004 0.010 A2 1.350 1.550 0.053 0.061 b 0.33 0.51 0.013 0.020 c 0.170 0.250 0.006 0.010 D 4.700 5.100 0.185 0.200 E 3.800 4.000 0.150 0.157 E1 5.800 6.200 0.228 0.244 e 1.270 (BSC) 0.050 (BSC) L 0.400 1.270 0.016 0.050 θ 0° 8° 0° 8° Land Pattern NOTES: 1. Compound dimension: 4.90×3.90； 2. Unit: mm; 3. General tolerance ±0.05mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation
http://www.union-ic.com Rev.04 Aug.2013 1 4 / 1 7 UM488/UM491 UM488EEPA DIP8 Outline Drawing DIMENSIONS Symbol MILLIMETERS INCHES Min Max Min Max A - 5.08 - 0.200 A1 0.38 - 0.015 - A2 3.18 4.45 0.125 0.175 A3 1.40 2.03 0.055 0.080 b 0.41 0.56 0.016 0.022 b1 1.14 1.65 0.045 0.065 C 0.20 0.30 0.008 0.012 D (8 PIN) 8.84 9.91 0.348 0.390 D1 0.13 2.03 0.005 0.080 E 7.62 8.26 0.300 0.325 E1 6.10 7.87 0.240 0.310 e 2.54 - 0.100 - eA 7.62 - 0.300 - eB - 10.16 - 0.400 L 2.92 3.81 0.115 0.150
http://www.union-ic.com Rev.04 Aug.2013 1 5 / 1 7 UM488/UM491 UM491EESE SOP14 Outline Drawing DIMENSIONS Symbol MILLIMETERS INCHES Min Max Min Max A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.004 0.010 b 0.35 0.49 0.014 0.019 C 0.19 0.25 0.007 0.010 E 3.80 4.00 0.150 0.157 D 8.55 8.75 0.337 0.344 e 1.27 0.050 H 5.80 6.20 0.228 0.244 L 0.40 1.27 0.016 0.050 Land Pattern NOTES: 1. Compound dimension: 8.65×3.90； 2. Unit: mm; 3. General tolerance ±0.05mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation
http://www.union-ic.com Rev.04 Aug.2013 1 6 / 1 7 UM488/UM491 UM491EEPE DIP14 Outline Drawing DIMENSIONS Symbol MILLIMETERS INCHES Min Max Min Max A - 5.08 - 0.200 A1 0.38 - 0.015 - A2 3.18 4.45 0.125 0.175 A3 1.40 2.03 0.055 0.080 b 0.41 0.56 0.016 0.022 b1 1.14 1.65 0.045 0.065 C 0.20 0.30 0.008 0.012 D 18.67 19.43 0.735 0.765 D1 0.13 2.03 0.005 0.080 E 7.62 8.26 0.300 0.325 E1 6.10 7.87 0.240 0.310 e 2.54 - 0.100 - eA 7.62 - 0.300 - eB - 10.16 - 0.400 L 2.92 3.81 0.115 0.150
http://www.union-ic.com Rev.04 Aug.2013 1 7 / 1 7 UM488/UM491 IMPORTANT NOTICE The information in this document has been ca refully reviewed and is believed to be accurate. Nonetheless, this document is subjec t to change without notice. Union assumes no responsibility for any inaccuracies that may be contained in this document, and makes no commitment to update or to keep current the contained information, or to notify a person or organization of any update. Union rese rves the right to make changes, at any time, in order to improve reliability, function or design and to attempt to supply the best product possible. Union Semiconductor, Inc Add: 7F, No. 5, Bibo Road, Shanghai 201203 Tel: 021-51097928 Fax: 021-51026018 Website: www.union-ic.com