Datasheet

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February 2009 Rev 7 1/19

ST485ERB

±15 kV ESD protected, 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

■ ESD protection:

– ± 15 kV (HBM)

– ± 8 kV (IEC-1000-4-2 contact discharge)

■ Allows up to 256 transceivers on the bus

Description

The ST485ERB is al low power transceiver for

RS-485 and RS-422 communication. Each driver

output and receiver input is protected against ±15

kV electrostatic discharge (HBM) ± 8 kV (IEC-

1000-4-2 contact discharge) shocks, without

latch-up. These parts contain one driver and one

receiver.

This transceiver draws 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 places the driver

outputs into a high-impedance state.

The ST485ERB is designed for bi-directional data

communications on multipoint bus transmission

line (half-duplex applications).

DIP-8 SO-8

Table 1. Device summary

Order code Temperature range Package Packaging

ST485ERBN - 40 to 85 °C DIP-8 50 parts per tube / 40 tube per box

ST485ERBDR - 40 to 85 °C SO-8 (tape and reel) 2500 parts per reel

www.st.com

Summary of content (19 pages)

PAGE 1
ST485ERB ±15 kV ESD protected, 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 ■ ESD protection: – ± 15 kV (HBM) – ± 8 kV (IEC-1000
PAGE 2
Contents ST485ERB Contents 1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PAGE 3
ST485ERB 1 Pin settings Pin settings Figure 1. Pin configuration Table 2.
PAGE 4
Truth tables 2 ST485ERB Truth tables Table 3. Truth table (driver) Inputs Note: Outputs RE DE DI B A X H H L H X H L H L X L X Z Z X = Don’t care; Z = High impedance Table 4. Truth table (receiver) Inputs Note: 4/19 Outputs RE DE L L ≥ +0.2V H L L ≤ -0.
PAGE 5
ST485ERB 3 Maximum ratings Maximum ratings Table 5. Absolute maximum ratings Symbol VCC Note: 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 Absolute maximum ratings are those values beyond which damage to the device may occur.
PAGE 6
Electrical characteristics 4 ST485ERB Electrical characteristics Table 6. Symbol ESD performance: transmitter outputs, receiver inputs Parameter Test conditions Min. Typ. Max. Unit ESD ESD protection voltage Human body model ±15 kV ESD ESD protection voltage IEC-1000-4-2 ±8 kV VCC = 5 V ± 5 %, TA = TMIN to TMAX, unless otherwise specified. Typical values are referred to TA = 25 °C Table 7.
PAGE 7
ST485ERB Electrical characteristics Table 7. Symbol DC electrical characteristics (continued) Parameter Test conditions (1) Min. Typ. Max. Unit 400 300 900 500 µA µA ICC No load supply current (2) VRE = 0V or VCC VDE = VCC VDE = 0V IOSD1 Driver short-circuit current, VO=High VO = -7 to 12V (3) 35 250 mA IOSD2 Driver short-circuit current, VO=Low VO = -7 to 12V (3) 35 250 mA IOSR Receiver short-circuit current VO = 0V to VCC 7 95 mA 1.
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Electrical characteristics ST485ERB (VCC = 5 V ± 5 %, TA = TMIN to TMAX, unless otherwise specified. Typical values are referred to TA = 25 °C) Table 9. Receiver switching characteristics Symbol Parameter Test conditions (1) Min. Typ. Max.
PAGE 9
ST485ERB 5 Test circuit and typical characteristics 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.
PAGE 10
Test circuit and typical characteristics 10/19 Figure 6. Driver propagation delay Figure 7.
PAGE 11
ST485ERB 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 ST485ERB 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.
PAGE 13
ST485ERB Figure 16. Receiver low level output voltage vs. temperature Test circuit and typical characteristics Figure 17. Differential driver output voltage vs.
PAGE 14
Package mechanical data 6 ST485ERB 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
ST485ERB 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.
PAGE 16
Package mechanical data ST485ERB 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 17
ST485ERB 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 18
Revision history ST485ERB 7 Revision history Table 10. Document revision history Date Revision 21-Mar-2006 3 Order codes has been updated and new template. 01-Aug-2006 4 Mistake in cover page description 300 mA ==> 300 µA. 25-Oct-2006 5 Order codes updated. 02-Dec-2008 6 Modified: device name Table 1 on page 1. 16-Feb-2008 7 Modified Note: on page 5.
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ST485ERB 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.