Datasheet

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February 2008 Rev 5 1/17

ST490AB

Low power high speed

RS-485/RS-422 transceiver

Features

■ Low supply current: 5 mA max

■ -7 V to 12 V common mode input voltage range

■ 70 mV typical input hysteresis

■ Designed for 25 Mbps operation

■ Operate from a single 5 V supply

■ ±4 kV ESD protection

■ Current limiting and thermal shutdown for

driver overload protection

Description

The ST490A is a low power transceiver for RS-

485 and RS-422 communications. The device

contains one driver and one receiver in full duplex

configuration. The ST490A draws 5 mA (typ.) of

supply current when unloaded or fully loaded with

disabled drivers. It operates from a single 5 V

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.

DIP-8 SO-8

Table 1. Device summary

Order code Temperature range Package Packaging

ST490ABN -40 to 85 °C DIP-8 50 parts per tube / 40 tube per box

ST490ABDR -40 to 85 °C SO-8 (tape and reel) 2500 parts per reel

www.st.com

Summary of content (17 pages)

PAGE 1
ST490AB Low power high speed RS-485/RS-422 transceiver Features ■ Low supply current: 5 mA max ■ -7 V to 12 V common mode input voltage range ■ 70 mV typical input hysteresis ■ Designed for 25 Mbps operation ■ Operate from a single 5 V supply ■ ±4 kV ESD protection ■ Current limiting and thermal shutdown for driver overload protection DIP-8 SO-8 Description The ST490A is a low power transceiver for RS485 and RS-422 communications.
PAGE 2
Contents ST490AB Contents 1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ST490AB Pin configuration 1 Pin configuration Figure 1. Pin connections Table 2.
PAGE 4
Truth tables ST490AB 2 Truth tables Table 3. Truth table (driver) Inputs DI Y Z L L H H H L Note: X = Don’t care; Z = High impedance Table 4. Truth table (receiver) Note: 4/17 Outputs Differential inputs Outputs A-B RO ≥ -0.2V H between -0.2V to 0.2V ? ≤-0.
PAGE 5
ST490AB Maximum ratings 3 Maximum ratings Table 5. Absolute maximum ratings Symbol Parameter VCC Supply voltage VDI Driver input voltage Value Unit 7 V -0.5 to 7 V VY, VZ Driver output voltage -7.5 to 12.5 V VA, VB Receiver input voltage -7.5 to 12.5 V -0.3 to (VCC + 0.3) V 3.5 kV VRO Receiver output voltage ESD Human body model Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
PAGE 6
Electrical characteristics ST490AB 4 Electrical characteristics Table 6. Electrical characteristics (VCC = 4.5 V to 5.5 V, TA = -40 to 85 °C, unless otherwise specified. Typical values are referred to TA = 25 °C) Symbol ISUPPLY Parameter Min. No load supply current Typ. Max. Unit 2 5 mA CIN Input capacitance 1.8 pF CYZ Driver output capacitance 1.2 pF Output capacitance 2.3 pF COUT Table 7. Transmitter electrical characteristics (VCC = 4.5 V to 5.
PAGE 7
ST490AB Table 8. Symbol Electrical characteristics Receiver electrical characteristics (VCC = 4.5 V to 5.5 V, TA = -40 to 85 °C, unless otherwise specified. Typical values are referred to TA = 25 °C) Parameter Test conditions Min.
PAGE 8
Test circuit and typical characteristics 5 Test circuit and typical characteristics Figure 2. Driver DC test load Figure 3.
PAGE 9
ST490AB Test circuit and typical characteristics Figure 4. Driver propagation delay Figure 5.
PAGE 10
Test circuit and typical characteristics ST490AB Figure 6. Receiver output current vs. output low voltage (output low) Figure 8. Driver diff. output voltage vs Figure 9. common mode voltage (diff. output low) Figure 10. driver short circuit current vs line voltage (output high) 10/17 Figure 7. Receiver output current vs. output high voltage (output high) Driver diff. output voltage vs common mode voltage (diff. output high) Figure 11. Receiver high level output voltage vs.
PAGE 11
ST490AB Test circuit and typical characteristics Figure 12.
PAGE 12
Package mechanical data 6 ST490AB Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark.
PAGE 13
ST490AB Package mechanical data 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.
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Package mechanical data ST490AB SO-8 mechanical data Dim. mm. Min. Typ. inch. Max. Min. Typ. Max. A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.04 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D 4.80 5.00 0.189 0.197 E 3.80 4.00 0.150 0.157 e 1.27 0.050 H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k ddd 8° (max.) 0.1 0.
PAGE 15
ST490AB Package mechanical data Tape & reel SO-8 mechanical data mm. inch. Dim. Min. A Typ. Max. Min. 330 Max. 12.992 C 12.8 D 20.2 0.795 N 60 2.362 T 13.2 Typ. 0.504 22.4 0.519 0.882 Ao 8.1 8.5 0.319 0.335 Bo 5.5 5.9 0.216 0.232 Ko 2.1 2.3 0.082 0.090 Po 3.9 4.1 0.153 0.161 P 7.9 8.1 0.311 0.
PAGE 16
Revision history ST490AB 7 Revision history Table 11. Document revision history Date Revision 06-Jul-2005 2 Typing error on table 2 - pin 5 non-inverting, pin 6 inverting. 04-May-2006 3 Order codes updated. 08-Nov-2007 4 Added: Table 1. 07-Feb-2008 5 Modified: Table 1 on page 1.
PAGE 17
ST490AB Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale.