Datasheet

ManualsBrandsSTMICROELECTRONICS ManualsInterface ICsInterface IC - transceivers RS422, RS485 1/1 SO 8

This is information on a product in full production.

December 2013 DocID9102 Rev 6 1/21

ST3485EB, ST3485EC

3.3 V powered, 15 kV ESD protected, up to 12 Mbps RS-485/

RS-422 transceiver

Datasheet - production data

Features

 ESD protection

– ±15 kV IEC 61000-4-2 air discharge

– ±8 kV IEC 61000-4-2 contact discharge

 Operate from a single 3.3 V supply - no charge

pump required

 Interoperable with 5 V logic

 1 µA low current shutdown mode max.

 Guaranteed 12 Mbps data rate

 -7 to 12 V common mode input voltage range

 Half duplex versions available

 Industry standard 75176 pinout

 Current limiting and thermal shutdown for

driver overload protection

 Guaranteed high receiver output state for

floating inputs with no signal present

 Allow up to 64 transceivers on the bus

 Available in

SO-8 package

Description

The ST3485EB/EC device is ±15 kV ESD

protected, 3.3 V low power transceiver for RS-485

and RS-422 communications. The device

contains one driver and one receiver in half

duplex configuration.

The ST3485E device transmits and receives at a

guaranteed data rate of at least 12 Mbps.

All transmitter outputs and receiver inputs are

protected to ±15 kV IEC 61000-4-2 air discharge.

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.

SO-8

Table 1. Device summary

Order code Temperature range Package Packaging

ST3485ECDR 0 to 70 °C SO-8 (tape and reel) 2500 parts per reel

ST3485EBDR -40 to 85 °C SO-8 (tape and reel) 2500 parts per reel

www.st.com

Summary of content (21 pages)

PAGE 1
ST3485EB, ST3485EC 3.3 V powered, 15 kV ESD protected, up to 12 Mbps RS-485/ RS-422 transceiver Datasheet - production data  Industry standard 75176 pinout  Current limiting and thermal shutdown for driver overload protection  Guaranteed high receiver output state for floating inputs with no signal present  Allow up to 64 transceivers on the bus  Available in SO-8 package SO-8 Description The ST3485EB/EC device is ±15 kV ESD protected, 3.3 V low power transceiver for RS-485 and RS-422 communications.
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Contents ST3485EB, ST3485EC Contents 1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ST3485EB, ST3485EC 1 Pin configuration Pin configuration Figure 1. Pin connections Table 2. Pin description Pin n° Symbol Name and function 1 RO Receiver output. If A > B by 200 mV, RO will be high; if A < B by 200 mV, RO will be low. 2 RE 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. 3 DE Driver output enable. The driver outputs are enabled by bringing DE high.
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Truth tables 2 ST3485EB, ST3485EC Truth tables Table 3. Truth table (driver) Inputs Outputs Mode RE DE DI B A X H H L H Normal X H L H L Normal L L X Z Z Normal H L X Z Z Shutdown Note: X = “don’t care”; Z = high impedance. Table 4. Truth table (receiver) Inputs Output Mode Note: 4/21 RE DE A-B RO L L ≥ 0.2 V H Normal L L ≤ -0.2 V L Normal L L Inputs open H Normal H L X Z Shutdown X = “don’t care”; Z = high impedance.
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ST3485EB, ST3485EC 3 Maximum ratings Maximum ratings Table 5. Absolute maximum ratings Symbol VCC Parameter Supply voltage Value Unit 7 V VI Control input voltage (RE, DE) -0.3 to 7 V VDI Driver input voltage (DI) -0.3 to 7 V VDO Driver output voltage (A, B) ±14 V VRI Receiver input voltage (A, B) ±14 V VRO Receiver output voltage (RO) -0.3 to (VCC + 0.3) V Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
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Electrical characteristics 4 ST3485EB, ST3485EC Electrical characteristics Table 7. Electrical characteristics (VCC = 3 V to 3.6 V, TA = -40 to 85 °C, unless otherwise specified. Typical values are referred to TA = 25 °C) Symbol ISUPPLY ISHDN Parameter Test conditions VCC Power supply current No load, DI = 0 V or VCC Shutdown supply current Min. Typ. Max. Unit DE = VCC, RE = 0 V or VCC 1.3 2.2 mA DE = 0 V, RE = 0 V 1.2 1.9 mA 0.002 1 µA DE = 0 V, RE = VCC, DI = 0 V or VCC Table 8.
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ST3485EB, ST3485EC Electrical characteristics Table 10. Receiver electrical characteristics (VCC = 3 V to 3.6 V, TA = -40 to 85 °C, unless otherwise specified. Typical values are referred to TA = 25 °C) Symbol Parameter Test conditions Min. Typ. Max. Unit 0.
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Electrical characteristics ST3485EB, ST3485EC Table 12. Receiver switching characteristics (VCC = 3 V to 3.6 V, TA = -40 to 85 °C, unless otherwise specified. Typical values are referred to TA = 25 °C) Symbol Parameter Test conditions tRPLH tRPHL Propagation delay tRPDS Typ. Max.
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ST3485EB, ST3485EC 5 Test circuits and typical characteristics Test circuits and typical characteristics Figure 2. Driver and VOC test load Figure 3. Driver VOD with varying common mode voltage test load Figure 4.
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Test circuits and typical characteristics ST3485EB, ST3485EC Figure 5. Drive differential output delay transition time test circuit ,1 &6 9 1. The input pulse is supplied by a generator with the following characteristics: PRR = 250 kHz, 50% duty cycle, tr ≤ 6.0 ns, ZO = 50 . 2. CL includes probe and stray capacitance. Figure 6. Drive differential output delay transition time waveform W'2 W'' &6 9 Figure 7.
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ST3485EB, ST3485EC Test circuits and typical characteristics Figure 8. Drive enable and disable times waveforms W3=+ RU W36+ &6 9 1. tPZH is valid if the driver is initially disabled (RE is high), tPSH is valid if the driver is initially in shutdown mode (RE is low). Figure 9. Drive propagation time test circuit ,1 &6 9 1. The input pulse is supplied by a generator with the following characteristics: PRR = 250 kHz, 50% duty cycle, tr ≤ 6.0 ns. 2.
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Test circuits and typical characteristics ST3485EB, ST3485EC Figure 10. Drive propagation time waveform $ 287 % 287 &6 9 Figure 11. Drive enable and disable times test circuit 9 RU 9 ,1 &6 9 1. The input pulse is supplied by a generator with the following characteristics: PRR = 250 kHz, 50% duty cycle, tr ≤ 6.0 ns. 2. CL includes probe and stray capacitance.
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ST3485EB, ST3485EC Test circuits and typical characteristics Figure 12. Drive enable and disable times waveforms W3=/ RU W36/ &6 9 1. tPZL is valid if the driver is initially disabled (RE is high), tPSL is valid if the driver is initially in shutdown mode (RE is low). Figure 13. Receiver propagation delay time test circuit ,1 &6 9 1. The input pulse is supplied by a generator with the following characteristics: PRR = 250 kHz, 50% duty cycle, tr ≤ 6.0 ns. 2.
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Test circuits and typical characteristics ST3485EB, ST3485EC Figure 15. Receiver enable and disable times test circuit 287 ,1 &6 9 1. The input pulse is supplied by a generator with the following characteristics: PRR = 250 kHz, 50% duty cycle, tr ≤ 6.0 ns. 2. CL includes probe and stray capacitance. Figure 16. Receiver enable and disable times waveform Figure 17.
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ST3485EB, ST3485EC Test circuits and typical characteristics Figure 18. Receiver enable and disable times waveform Figure 19. Receiver enable and disable times waveform Figure 20. Receiver output current vs. output low voltage Figure 21. Receiver output current vs.
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Test circuits and typical characteristics ST3485EB, ST3485EC Figure 22. Low level driver output capability Figure 23. High level driver output capability Figure 24. Receiver input characteristics Figure 25. Driver short-circuit current Figure 26.
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ST3485EB, ST3485EC 6 Package information Package information 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.
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Package information ST3485EB, ST3485EC Figure 27. SO-8 package outline & Table 13. SO-8 package mechanical data Dimensions Symbol mm Min. Typ. inch Max. Min. 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 18/21 Typ.
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ST3485EB, ST3485EC Package information Figure 28. Tape and reel SO-8 outline Table 14. Tape and reel SO-8 mechanical data Dimensions Symbol mm Min. A Typ. inch 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 7 ST3485EB, ST3485EC Revision history Table 15. Document revision history Date Revision 20-Jun-2005 2 Mistake on table 12 tZL(SHDN) ms ==> µs. 30-Aug-2005 3 Remove (TRUE) on title, description has been updated in cover page. The VTH and VTH values are changed in table 10. 07-Apr-2006 4 Order codes updated. 12-Nov-2007 5 Added Table 1.
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ST3485EB, ST3485EC 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.