ST485A VERY HIGH SPEED LOW POWER RS-485/RS-422 TRANSCEIVER ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ LOW SUPPLY CURRENT: 5mA MAX HIGH DATA RATE > 30Mbps DESIGNED FOR RS 485 INTERFACE APPLICATIONS -7 TO 12 COMMON MODE INPUT VOLTAGE RANGE DRIVER MANTAINS HIGH IMPEDANCE IN 3-STATE OR WITH THE POWER OFF 70mV TYPICAL INPUT HYSTERESIS OPERATE FROM SINGLE 5 SUPPLY ±4kV ESD PROTECTION CURRENT LIMITING AND THERMAL SHUTDOWN FOR DRIVER OVERLOAD PROTECTION LATCH-UP FREE UP TO 500mA DESCRIPTION The ST485A is a low power, high speed transceiver for RS-485 and RS-422 communications. The device contains one driver and one receiver in half duplex configuration. The ST485A draws 3mA (typ.) of supply current when DIP SOP unloaded or fully loaded with disabled drivers. It operates from a single 5V supply. Driver is short-circuit current limited and is protected against excessive power dissipation by thermal shutdown circuitry that place the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic high output if both inputs are open circuit. The ST485A is designed for bi-directional data communications or multipoint bus transmission lines. ORDERING CODES Type Temperature Range Package Comments ST485ACN ST485ABN ST485ACD ST485ABD ST485ACDR ST485ABDR 0 to 70 °C -40 to 85 °C 0 to 70 °C -40 to 85 °C 0 to 70 °C -40 to 85 °C DIP-8 DIP-8 SO-8 (Tube) SO-8 (Tube) SO-8 (Tape & Reel) SO-8 (Tape & Reel) 50parts per tube / 40tube per box 50parts per tube / 40tube per box 100parts per tube / 20tube per box 100parts per tube / 20tube per box 2500 parts per reel 2500 parts per reel November 2002 1/13 ST485A PIN CONFIGURATION PIN DESCRIPTION PlN N° SYMBOL 1 RO 2 RE 3 DE 4 DI 5 6 7 GND A B VCC 8 NAME AND FUNCTION Receiver Output. If A>B by 200mV, RO will be high; if A<B by 200mV, RO will be low Receiver Output Enable. RO is enabled when RE is low; RO is high impedance when RE is high. If RE is high and DE is low, the device will enter a low power shutdown mode. Driver Output Enable. The driver outputs are enabled by bringing DE high. They are high impedance when DE is low. If RE is high DE is low, the device will enter a low-power shutdown mode. If the driver outputs are enabled, the part functions as line driver, while they are high impedance, it functions as line receivers if RE is low. Driver Input. A low on DI forces output A low and output B high. Similarly, a high on DI forces output A high and output B low Ground Non-inverting Receiver Input and Non-inverting Driver Output Inverting Receiver Input and Inverting Driver Output Supply Voltage: VCC= 4.75V to 5.25V TRUTH TABLE (RECEIVER) TRUTH TABLE (DRIVER) INPUTS OUTPUTS INPUTS OUTPUT MODE RE DE DI B A X X L H H L H L X L H Z H L Z X= Don’t Care; Z=High Impedance 2/13 MODE RE DE Normal Normal Normal L L L L L L A-B RO ≥ -0.2V ≤ -0.2V Inputs Open H L H X= Don’t Care; Z=High Impedance Normal Normal Normal ST485A ABSOLUTE MAXIMUM RATINGS Symbol VCC VI Parameter Value Supply Voltage Unit 7 V -0.3 to 7 V -0.3 to 7 V -7.5 to 12.5 V Control Input Voltage (RE, DE) VDI Driver Input Voltage (DI) VDO Driver Output Voltage (A, B) VRI Receiver Input Voltage (A, B) -7.5 to 12.5 V VRO Receiver Output Voltage (RO) -0.3 to (VCC + 0.3) V Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. ELECTRICAL CHARACTERISTICS VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred to TA = 25°C, VCC = 5V) (See Note 1) Symbol Parameter ISUPPLY VCC Power Supply Current Test Conditions No Load, VRE=0V or VCC Min. Typ. Max. Unit VDE=VCC 2.3 5 mA VDE=0V 2.6 5 mA CI/O Input/Output Capacitance 10 pF CAB Driver Output Capacity 10 pF LOGIC INPUT ELECTRICAL CHARACTERISTICS VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred to TA = 25°C, VCC = 5V) (See Note 1 Symbol Parameter Test Conditions VIL Input Logic Threshold Low DE, DI, RE VIH Input Logic Threshold High DE, DI, RE IIN1 Logic Input Current DE, DI, RE IIN2 Input Current (A, B) VDE=0V, VCC= 0 or 5.25V Min. Typ. Max. 0.8 2 Unit V V ± 2.0 µA VIN=12V 1 mA VIN=-7V -0.8 mA 3/13 ST485A TRANSMITTER ELECTRICAL CHARACTERISTICS VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred to Ta = 25°C, VCC = 5V) (See Note 1) Symbol Parameter VOD1 Differential Driver Output (No load) Differential Driver Output (With Load) Change in magnitude of Driver Differential Output Voltage for Complementary Output States (Note1) Driver Common Mode Output Voltage Change in magnitude of Driver Common Mode Output Voltage (Note1) Driver Short Circuit Output Current VOD2 ∆VOD VOC ∆VOC IOSD Test Conditions RL= 54Ω (RS-422) VCM=-7V to 12V Min. 1.5 RL= 27Ω or 50Ω RL= 27Ω or 50Ω Typ. Max. Unit 5 V 2.7 5 V 0 0.2 V 3 V 0.2 V ± 250 mA 1 RL= 54Ω or 100Ω 0 VO=-7V to 12V RECEIVER ELECTRICAL CHARACTERISTICS VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred to Ta = 25°C, VCC = 5V) (See Note 1) Symbol VTH ∆VTH VOH VOL IOZR RRIN IOSR 4/13 Parameter Test Conditions Min. Receiver Differential Threshold Voltage Receiver Input Hysteresis VCM = -7V to 12V Receiver Output High Voltage Receiver Output Low Voltage 3-State (High Impedance) Output Current at Receiver Receiver Input Resistance IOUT = -4mA, VID = 200mV VCM = -7V to 12V 12 Receiver Short-Circuit Current VO = 0V to VCC 7 Typ. -0.2 VCM = 0V 3.5 IOUT = 4mA, VID = -200mV Max. Unit 0.2 V 70 mV 4.7 V 0.2 VO = 0.4V to 2.4V 0.4 V ±1 µA 24 KΩ 95 mA ST485A DRIVER SWITCHING CHARACTERISTICS VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred to Ta = 25°C, VCC = 5V) (See Note 1, 3) Symbol Parameter Test Conditions Min. Max. DR Maximum Data Rate Jitter <5% Propagation Delay Input to Output RL= 54Ω CL1=CL2=50pF, (Figure 1) 18 30 ns RL= 54Ω CL1=CL2=50pF, (Figure 1) 0.5 2 ns tTLH tTHL Differential Output Delay Skew Rise or Fall Differential Time RL= 54Ω CL1=CL2=50pF, (Figure 1) 8 12 ns tPZL Output Enable Time CL= 50pF S1 Closed 30 ns tPZH Output Enable Time CL= 50pF S2 Closed 30 ns tPHZ Output Disable Time CL= 15pF S2 Closed 30 ns tPLZ Output Disable Time CL= 15pF S1 Closed 30 ns 2 ns 6 ns tSK(EN) tSK(DS) Synchronous Driver Operation A-B at Enable Synchronous Driver Operation A-B at Disable 50 Unit tPLH tPHL tSKEW 30 Typ. 4 Mbps RECEIVER SWITCHING CHARACTERISTICS VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred to Ta = 25°C, VCC = 5V) (See Note 1, 3) Symbol Parameter Test Conditions Min. Typ. Max. Unit Propagation Delay CL = 15pF 18 30 ns CL = 15pF 0.5 2 ns tPZL |tPLH - tPHL| Propagation Delay Skew Output Enable Time CRL = 15pF S1 Closed 7 12 ns tPZH Output Enable Time CRL = 15pF S2 Closed 7 12 ns tPHZ Output Disable Time CRL = 15pF S2 Closed 7 12 ns tPLZ Output Disable Time CRL = 15pF S1 Closed 7 12 ns tPLH tPHL tRPDS Note 1: All currents into device pins are positive; all cuttents out of device pins are negative; all voltages are referenced to device ground unless specified. Note 2: Applies to peak current. See typical Operating Characteristics. Note 3: tr=tf ≤ 6ms 5/13 ST485A TEST CIRCUITS AND TYPICAL CHARACTERISTICS Figure 1 : Driver DC Test Load Figure 2 : Receiver Timing Test Load Figure 3 : Drive/Receiver Timing Test Circuit 6/13 ST485A Figure 4 : Driver Timing Test Load Figure 5 : Driver Propagation Delay 7/13 ST485A Figure 6 : Driver Enable and Disable Time Figure 7 : Receiver Propagation Delay 8/13 ST485A Figure 8 : Receiver Enable and Disable Time Figure 9 : Receiver Output Current vs Output Voltage (Output Low) Figure 10 : Receiver Output Current vs Output Voltage (Output High) 9/13 ST485A Figure 11 : Driver Diff. Output Voltage vs Common Mode Voltage (Diff. Output Low) Figure 14 : Driver Short Circuit Current vs. Line Voltage (Output Low) Figure 12 : Driver Diff. Output Voltage vs Common Mode Voltage (Diff. Output Low) Figure 15 : Receiver Input Current vs Input Voltage Figure 13 : Driver Short Circuit Current vs Line Voltage (Output High) 10/13 ST485A Plastic DIP-8 MECHANICAL DATA mm. inch DIM. MIN. A TYP MAX. MIN. 3.3 TYP. MAX. 0.130 a1 0.7 B 1.39 1.65 0.055 0.065 B1 0.91 1.04 0.036 0.041 b b1 0.028 0.5 0.38 0.020 0.5 D 0.015 0.020 9.8 0.386 E 8.8 0.346 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 F 7.1 0.280 I 4.8 0.189 L Z 3.3 0.44 0.130 1.6 0.017 0.063 P001F 11/13 ST485A SO-8 MECHANICAL DATA DIM. mm. MIN. TYP A a1 inch MAX. MIN. TYP. 1.75 0.1 0.068 0.25 a2 MAX. 0.003 0.009 1.65 0.064 a3 0.65 0.85 0.025 0.033 b 0.35 0.48 0.013 0.018 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.019 c1 45˚ (typ.) D 4.8 5.0 0.189 0.196 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 F 3.8 4.0 0.149 0.157 L 0.4 1.27 0.015 0.050 M S 0.6 0.023 8˚ (max.) 0016023 12/13 ST485A Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. © The ST logo is a registered trademark of STMicroelectronics © 2002 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - United States. © http://www.st.com 13/13