Datasheet

ManualsBrandsST ManualsDriversTransceiver, RS-485/RS-422, 7V, 900uA, SO-8

February 2009 Rev 16 1/19

ST485B

ST485C

Low power RS-485/RS-422 transceiver

Features

■ Low quiescent current: 300 µA

■ Designed for RS-485 interface application

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

■ Driver maintains high impedance in 3-state or

with the power OFF

■ 70 mV typical input hysteresis

■ 30 ns propagation delay, 5 ns skew

■ Operate from a single 5 V supply

■ Current limiting and thermal shutdown for

driver overload protection

■ Allows up to 64 transceivers on the bus

Description

The ST485 is al low power transceiver for RS-485

and RS-422 communication. Each part contains

one driver and one receiver.

This transceiver draw 300 µA (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 placed the driver

outputs into a high-impedance state.

The ST485 is designed for bi-directional data

communications on multipoint bus transmission

line (half-duplex applications).

The ST485 is available in three temperature

range: commercial (0 °C to 70 °C), industrial (- 40

°C to 85 °C) and automotive (- 55 °C to 125 °C).

DIP-8 SO-8

Table 1. Device summary

Order code Temperature range Package Packaging

ST485CN 0 to 70 °C DIP-8 50 parts per tube / 40 tube per box

ST485BN - 40 to 85 °C DIP-8 50 parts per tube / 40 tube per box

ST485CDR 0 to 70 °C SO-8 (tape and reel) 2500 parts per reel

ST485BDR - 40 to 85 °C SO-8 (tape and reel) 2500 parts per reel

www.st.com

Summary of content (19 pages)

PAGE 1
ST485B ST485C Low power RS-485/RS-422 transceiver Features ■ Low quiescent current: 300 µA ■ Designed for RS-485 interface application ■ - 7 V to 12 V common mode input voltage range ■ Driver maintains high impedance in 3-state or with the power OFF ■ 70 mV typical input hysteresis ■ 30 ns propagation delay, 5 ns skew ■ Operate from a single 5 V supply ■ Current limiting and thermal shutdown for driver overload protection ■ Allows up to 64 transceivers on the bus DIP-8 SO-8 The ST485 is
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Contents ST485B - ST485C Contents 1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ST485B - ST485C Pin configuration 1 Pin configuration Figure 1. Pin connections Table 2.
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Truth tables ST485B - ST485C 2 Truth tables Table 3. Truth table (driver) Inputs Outputs RE DE DI B A X H H L H X H L H L X L X Z Z Note: X = Don’t care; Z = High impedance Table 4. Truth table (receiver) Inputs Note: 4/19 Outputs RE DE A-B L L ≥ +0.2V H L L ≤ -0.
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ST485B - ST485C Maximum ratings 3 Maximum ratings Table 5. Absolute maximum ratings Symbol VCC Parameter Supply voltage Value Unit 7 V VI Control input voltage (RE, DE) -0.5 to (VCC + 0.5) V VDI Driver input voltage (DI) -0.5 to (VCC + 0.5) V VDO Driver output voltage (A, B) ± 14 V VRI Receiver input voltage (A, B) ± 14 V VRO Receiver output voltage (RO) -0.5 to (VCC + 0.5) V Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
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Electrical characteristics 4 ST485B - ST485C Electrical characteristics VCC = 5 V ± 5 %, TA = TMIN to TMAX, unless otherwise specified. Typical values are referred to TA = 25 °C Table 6. DC electrical characteristics Value Symbol Parameter Test conditions (1) -40 to 85 °C Min.
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ST485B - ST485C Table 6. Electrical characteristics DC electrical characteristics (continued) Value Symbol Parameter Test conditions (1) -40 to 85 °C Min. Typ. -55 to 125 °C Max. Min. Max. Unit IOSD1 Driver short-circuit current, VO=High VO = -7 to 12V (3) 35 250 35 250 mA IOSD2 Driver short-circuit current, VO=Low VO = -7 to 12V (3) 35 250 35 250 mA IOSR Receiver short-circuit current VO = 0V to VCC 7 95 7 95 mA 1.
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Electrical characteristics ST485B - ST485C VCC = 5 V ± 5%, TA = TMIN to TMAX, unless otherwise specified. Typical values are referred to TA = 25 °C Table 8. Receiver switching characteristics Value Symbol Parameter Test conditions (1) -40 to 85 °C Min. Typ. Max. 20 130 210 -55 to 125°C Min. Unit Max.
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ST485B - ST485C Test circuit and typical characteristics 5 Test circuit and typical characteristics Figure 2. Driver DC test load Figure 3. Receiver timing test load Figure 4. Drive/receiver timing test circuit Figure 5.
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Test circuit and typical characteristics 10/19 Figure 6. Driver propagation delay Figure 7.
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ST485B - ST485C Test circuit and typical characteristics Figure 8. Receiver propagation delay Figure 9.
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Test circuit and typical characteristics Figure 10. Receiver output current vs. output low voltage ST485B - ST485C Figure 11. Receiver output current vs. output high voltage Figure 12. Driver output current vs. output low Figure 13. Driver output current vs. output voltage high voltage Figure 14. Supply current vs. temperature 12/19 Figure 15. Receiver high level output voltage vs.
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ST485B - ST485C Figure 16. Receiver low level output voltage vs. temperature Test circuit and typical characteristics Figure 17. Differential driver output voltage vs.
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Package mechanical data 6 ST485B - ST485C Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK is an ST trademark.
PAGE 15
ST485B - ST485C 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 ST485B - ST485C 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.
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ST485B - ST485C 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.
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Revision history ST485B - ST485C 7 Revision history Table 9. Document revision history Date Revision 21-Mar-2006 12 Order codes has been updated and new template. 02-Aug-2006 13 Mistake in cover page first row mA ==> µA. 08-Nov-2006 14 Added: Table 1. 07-Feb-2008 15 Modified: Table 1 on page 1. 16-Feb-2009 16 Modified Note: on page 5.
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ST485B - ST485C 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.