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STMicroelectronics ST485ECDR
- Part No.:
- ST485ECDR
- Manufacturer:
- STMicroelectronics
- Category:
- Drivers, Receivers, Transceivers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ST485ECDR.pdf
- Description:
- IC TRANSCEIVER HALF 1/1 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:7,974
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Product details
Overview
ST485ECDR from STMicroelectronics is a half-duplex RS-485/RS-422 transceiver in SO-8 package, operating from a single 5 V supply with 300 µA quiescent current, ±15 kV HBM ESD protection, and 5 Mbps maximum data rate. It integrates one driver and one receiver for bidirectional multipoint bus communication in industrial automation networks.
For engineers reviewing the ST485ECDR datasheet, ST485ECDR pinout, ST485ECDR application, or ST485ECDR equivalent, key selection criteria include common-mode input range (–7 V to +12 V), 70 mV receiver hysteresis for noise immunity, 30 ns driver propagation delay, and thermal shutdown protection during driver overload.
Technical Context
The ST485ECDR implements a half-duplex transceiver architecture with independent enable controls: RE (receiver enable) and DE (driver enable). Its driver features short-circuit current limiting and thermal shutdown, forcing outputs into high-impedance state under fault conditions.
Receiver inputs accept –7 V to +12 V common-mode voltage and exhibit 70 mV typical hysteresis; driver outputs deliver ≥1.5 V differential voltage into 27 Ω (RS-485) or 50 Ω (RS-422) loads, supporting robust noise margin in electrically noisy environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 5 V ±5 % - fixed single-supply operation compatible with standard logic rails |
| Quiescent Current | 300 µA typ. - enables low-power remote nodes and battery-backed systems |
| ESD Protection | ±15 kV HBM, ±8 kV IEC-1000-4-2 contact - eliminates need for external TVS on A/B lines |
| Common-Mode Range | –7 V to +12 V - supports long cable runs with ground potential differences |
| Max Data Rate | 5 Mbps - suitable for high-speed factory floor control and PLC backplane links |
| Propagation Delay | 30 ns typ. (driver), 130 ns typ. (receiver) - ensures timing predictability in synchronous multi-drop protocols |
| Input Hysteresis | 70 mV typ. - rejects high-frequency noise on differential bus without external filtering |
Pinout & Package
ST485ECDR is housed in an SO-8 surface-mount package (5.00 mm × 4.00 mm, 1.27 mm pitch), RoHS-compliant and ECOPACK® certified.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 RO | Receiver output | CMOS-compatible logic-level output driving MCU UART RX line |
| 2 RE | Receiver enable (active low) | Controls receiver activation; high-Z when disabled to prevent bus contention |
| 3 DE | Driver enable (active high) | Enables driver output only when asserted; prevents simultaneous TX/RX conflict |
| 4 DI | Driver input | Accepts TTL/CMOS logic from MCU UART TX, level-shifted internally |
| 5 GND | Ground reference | Signal return for all internal circuitry and biasing networks |
| 6 A | Non-inverting bus terminal | Connects to RS-485 bus A line; outputs high during logic '1' transmission |
| 7 B | Inverting bus terminal | Connects to RS-485 bus B line; outputs low during logic '1' transmission |
| 8 VCC | Positive supply | 5 V power input; powers both driver and receiver sections |
Key Features
| Feature | Design Value |
|---|---|
| Thermal shutdown protection | Automatically disables driver outputs during sustained short-circuit, preventing latch-up or permanent damage |
| High-impedance driver disable | Driver outputs enter true high-Z state when DE = low or VCC = 0, enabling safe bus sharing |
| Wide common-mode input range | –7 V to +12 V allows interoperability across disparate ground domains in distributed systems |
| Low propagation skew | 5 ns max driver output skew ensures clean differential edge alignment for timing-critical receivers |
| 3-state receiver output | RO enters high-Z when RE = high, permitting shared MCU RX line with other peripherals |
Applications
| Industrial PLC Networks | Building Automation Systems |
|---|---|
Use Scenario: Multi-node Modbus RTU network connecting temperature controllers, I/O modules, and HMIs over 1200 m twisted-pair cable. IC Role / Device Role / Timing Role: Half-duplex transceiver managing bidirectional serial data exchange between master and slave nodes. Use Value: ±15 kV ESD protection prevents field failures from handling-induced discharges; 300 µA quiescent current extends uptime in unpowered standby states. | Use Scenario: Central HVAC controller communicating with zone dampers, CO₂ sensors, and VAV boxes via daisy-chained RS-485 bus. IC Role / Device Role / Timing Role: Bus interface IC translating UART signals to differential RS-485 for noise-immune long-distance signaling. Use Value: –7 V to +12 V common-mode range accommodates ground offsets across large buildings; 5 Mbps capability supports fast configuration updates. |
| Energy Metering Gateways | Factory Floor Test Equipment |
Use Scenario: Smart meter concentrator aggregating consumption data from 256+ submeters using RS-485 multidrop topology. IC Role / Device Role / Timing Role: Low-power transceiver enabling high node density on shared bus without signal degradation. Use Value: Supports up to 256 unit loads per bus segment; 70 mV hysteresis suppresses false triggering from electromagnetic interference near switchgear. | Use Scenario: Automated test fixture communicating with DUTs (devices under test) via RS-485 for firmware upload and calibration verification. IC Role / Device Role / Timing Role: Robust physical layer interface ensuring reliable command/response cycles in EMI-heavy production environments. Use Value: Thermal shutdown protects against accidental bus shorts during probe contact; 30 ns driver delay enables precise timing synchronization across test sequences. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar RS-485 transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX485ESA+ | Same SO-8 package, 350 µA quiescent current, ±15 kV HBM, but no IEC-1000-4-2 contact discharge rating | Lacks certified 8 kV contact ESD - requires external protection in high-handling-volume deployments | Select when cost sensitivity outweighs certified contact ESD requirements and thermal shutdown is not critical |
| SN65HVD72DR | 3.3 V supply only, 1/8 unit load, ±16 kV HBM, integrated 120 Ω termination resistor | Not 5 V compatible; built-in termination reduces board space but limits flexibility in bus topology design | Select for 3.3 V systems needing simplified layout and higher ESD margin, accepting fixed termination |
Compared with MAX485ESA+ and SN65HVD72DR, ST485ECDR uniquely combines 5 V operation, certified IEC-1000-4-2 contact ESD, thermal shutdown, and full 1-unit-load drive strength - making it optimal for industrial RS-485 nodes requiring robustness, compatibility, and bus scalability.
Availability
ST485ECDR is available at Aetrix Electronics and suitable for industrial PLC networks, building automation systems, energy metering gateways, and factory floor test equipment requiring stable component supply across extended product lifecycles.
Supply support for ST485ECDR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, analog ICs, power devices, and sensors for industrial, automotive, and consumer markets.
The ST485E series belongs to ST's industrial interface portfolio, engineered specifically for ruggedized RS-485/RS-422 communication in harsh electrical environments where reliability, ESD resilience, and thermal safety are non-negotiable.
FAQ
What is the operating temperature range for ST485ECDR?
The ST485ECDR is rated for 0 °C to +70 °C ambient operation, matching commercial-grade industrial control applications. This range is validated per the device summary table and supported by electrical characteristics tested across TMIN to TMAX. It is distinct from the ST485EBD (–40 °C to +85 °C) and ST485EXDR (–55 °C to +125 °C) variants.
Does ST485ECDR support full-duplex RS-422 operation?
No. ST485ECDR is a half-duplex transceiver with shared A/B bus terminals and separate RE/DE controls. It lacks independent transmit and receive differential pairs required for full-duplex RS-422. For full-duplex, ST offers the ST3485 or ST75176 families with dedicated TX+/TX− and RX+/RX− pins.
Can ST485ECDR be used with 3.3 V logic interfaces?
Yes - its DI, RE, and DE inputs are 5 V tolerant and accept 3.3 V logic levels (VIH = 2.0 V min, VIL = 0.8 V max), allowing direct connection to 3.3 V MCUs. However, it requires a 5 V VCC supply; no internal LDO or dual-supply support is provided.
How many ST485ECDR units can connect to a single RS-485 bus?
Up to 256 ST485ECDR transceivers may share one RS-485 bus segment, as confirmed in the device description and supported by its 1/8 unit load input resistance (RIN = 96 kΩ, equivalent to 0.125 unit load). This enables high-density node deployment without repeaters in Modbus or custom protocol networks.
ST485ECDR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Transceiver
- Protocol:
- RS422, RS485
- Number of Drivers/Receivers:
- 1/1
- Duplex:
- Half
- Receiver Hysteresis:
- 70 mV
- Data Rate:
- 5Mbps
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
ST485ECDR FAQ
1.How can I place an order for ST485ECDR through Aetrix?
Please submit a Request for Quotation (RFQ) for ST485ECDR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ST485ECDR reliable?
The price and inventory of ST485ECDR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST485ECDR is usually 5 days.
3.What payment methods are accepted for ST485ECDR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST485ECDR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ST485ECDR?
ST485ECDR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ST485ECDR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ST485ECDR?
For technical support, including ST485ECDR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST485ECDR requirements.
6.How does Aetrix verify that ST485ECDR is sourced from the original manufacturer or authorized distributors?
All ST485ECDR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ST485ECDR meets industry standards.
7.What is the process for return or replacement of ST485ECDR?
All ST485ECDR units undergo pre-shipment inspection (PSI). If there is an issue with ST485ECDR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ST485ECDR part is unused and in its original packaging.
Return procedure for ST485ECDR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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