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STMicroelectronics ST485ECN
- Part No.:
- ST485ECN
- Manufacturer:
- STMicroelectronics
- Category:
- Drivers, Receivers, Transceivers
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
ST485ECN.pdf
- Description:
- IC TRANSCEIVER HALF 1/1 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,792
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Product details
Overview
ST485ECN from STMicroelectronics is a half-duplex RS-485/RS-422 transceiver in SO-8 package, featuring ±15 kV HBM ESD protection, 300 µA quiescent current, and 5 Mbps data rate. It integrates one driver and one receiver, operates from a single 5 V supply, and supports up to 256 nodes on a multipoint bus for industrial automation communication.
For engineers reviewing the ST485ECN datasheet, ST485ECN pinout, ST485ECN application, or ST485ECN equivalent, key selection criteria include common-mode range (–7 V to +12 V), input hysteresis (70 mV typ.), propagation delay (30 ns typ.), thermal shutdown protection, and SO-8 footprint compatibility with legacy RS-485 designs.
Technical Context
The ST485ECN implements a fail-safe receiver with differential threshold of ±0.2 V and 70 mV hysteresis to reject noise in electrically noisy industrial environments. Its driver includes current limiting and thermal shutdown, forcing outputs into high-impedance during overload - critical for bus integrity in multi-drop networks.
Control logic uses independent RE (receiver enable) and DE (driver enable) pins to support precise half-duplex timing control. The device maintains high-impedance driver output when powered down or in 3-state mode, preventing bus contention during power sequencing or sleep states.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 5 V ±5% - fixed single-supply operation; no level-shifting required for 5 V controller interfaces |
| Quiescent Current | 300 µA typ. - enables low-power remote sensor nodes and battery-backed systems |
| Data Rate | 5 Mbps - supports high-speed fieldbus segments in PLC backplanes and motor drives |
| Common-Mode Range | –7 V to +12 V - accommodates ground potential differences across long cable runs (up to 1200 m) |
| ESD Protection | ±15 kV HBM - eliminates need for external TVS diodes in panel-mounted I/O modules |
| Differential Output | 1.5–5 V (no load/load) - ensures robust signal margin over 27 Ω RS-485 termination |
| Propagation Delay | 30 ns typ. - enables tight timing budgets in synchronous multi-node polling architectures |
Pinout & Package
ST485ECN is housed in an industry-standard SO-8 (Small Outline, 150 mil width) package with 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 microcontroller UART RX line |
| 2 RE | Receiver enable (active-low) | Asserting low enables receiver; high places RO in high-impedance state |
| 3 DE | Driver enable (active-high) | Asserting high enables driver; low forces A/B into high-Z for bus release |
| 4 DI | Driver input | TTL/CMOS-compatible input accepting UART TX signal directly |
| 5 GND | Ground reference | Signal return for both driver and receiver sections; must be star-connected in noisy environments |
| 6 A | Non-inverting bus terminal | Connects to RS-485 bus A line; outputs positive differential voltage when driving |
| 7 B | Inverting bus terminal | Connects to RS-485 bus B line; outputs negative differential voltage when driving |
| 8 VCC | Positive supply | 5 V power input; requires local 100 nF ceramic decoupling adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| Thermal shutdown protection | Automatically disables driver output during sustained short-circuit events, preserving device and bus integrity |
| 3-State driver control | Independent DE pin allows precise bus arbitration timing without relying on microcontroller GPIO sequencing delays |
| High node count support | 96 kΩ receiver input resistance enables connection of up to 256 transceivers on a single RS-485 segment |
| Fail-safe receiver | Guarantees logic-high RO output when bus is idle, open, or shorted - prevents spurious UART framing errors |
| Low EMI driver slew rate | Controlled edge rates (15–40 ns) reduce radiated emissions in EMC-sensitive industrial enclosures |
Applications
| Industrial PLC Backplane | Building Automation Controller |
|---|---|
Use Scenario: Interconnecting I/O modules and CPU units across a DIN-rail mounted PLC chassis using twisted-pair backplane wiring. IC Role / Device Role / Timing Role: Half-duplex transceiver managing time-sliced command/response traffic between master and up to 32 slave modules. Use Value: 30 ns propagation delay and 5 Mbps capability ensure deterministic cycle times under 100 µs per module poll in 16-slot configurations. | Use Scenario: Linking HVAC controllers, lighting panels, and occupancy sensors over 300 m RS-485 trunk lines in commercial buildings. IC Role / Device Role / Timing Role: Bus interface IC translating UART commands into differential signals resilient to 4 kV surge transients induced by elevator motors. Use Value: ±15 kV HBM ESD rating and –7 V to +12 V common-mode range eliminate external protection components, reducing BOM cost by $0.18/unit. |
| Smart Energy Meter Interface | Factory Floor Robotics Network |
Use Scenario: Enabling DLMS/COSEM protocol communication between utility meters and concentrators via outdoor-rated RS-485 links. IC Role / Device Role / Timing Role: Isolated bus transceiver (when paired with digital isolator) handling secure meter read requests and firmware updates. Use Value: 300 µA quiescent current extends battery life in solar-powered concentrators to >5 years between replacements. | Use Scenario: Synchronizing motion controllers and servo drives across a 50 m production line using daisy-chained RS-485 cabling. IC Role / Device Role / Timing Role: Robust physical layer interface maintaining signal integrity amid 60 A motor switching noise and welding EMI. Use Value: 70 mV input hysteresis rejects common-mode noise spikes exceeding 100 mVpp, eliminating false packet reception in real-time motion profiles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar RS-485 transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX485CPA+ | Higher quiescent current (300 µA vs. 230 µA typ.), no thermal shutdown, same SO-8 pinout | Lacks driver fault protection; unsuitable for unattended equipment with risk of bus shorts | Select when thermal protection is not required and legacy MAX design reuse is prioritized |
| SN65HVD72DR | Lower ESD rating (±12 kV HBM), higher supply current (650 µA), integrated 120 Ω termination | Includes bus termination resistors but consumes more power; not drop-in due to different enable logic polarity | Choose for space-constrained designs where board area savings outweigh ESD margin loss |
Compared with MAX485CPA+ and SN65HVD72DR, the ST485ECN provides superior fault resilience via thermal shutdown and highest ESD immunity, making it optimal for unmonitored industrial deployments where bus reliability is non-negotiable.
Availability
ST485ECN is available at Aetrix Electronics and suitable for industrial PLC backplanes, building automation controllers, smart energy meter interfaces, and factory floor robotics networks requiring stable component supply across extended product lifecycles.
Supply support for ST485ECN 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.
The ST485E series belongs to ST's industrial interface portfolio, engineered specifically for robust, low-power RS-485/RS-422 communication in harsh electromagnetic environments with wide temperature and ground-potential variation.
FAQ
What is the operating temperature range for ST485ECN?
The ST485ECN is rated for 0 °C to +70 °C ambient operation, matching the commercial-grade variant in the ST485E family. This range supports indoor industrial control cabinets, HVAC controllers, and metering equipment without active thermal management.
Does ST485ECN support full-duplex RS-422 operation?
No. ST485ECN is a half-duplex transceiver with shared A/B bus terminals and separate RE/DE control pins. It lacks independent transmit/receive differential pairs required for full-duplex RS-422; use ST3485 or ST75176 for full-duplex applications.
Can ST485ECN be used without external termination resistors?
Yes - termination is optional and depends on cable length and data rate. At 5 Mbps over ≤10 m, stub-free point-to-point links may operate reliably without termination. For longer runs or multi-drop topologies, a 120 Ω resistor between A and B at the farthest node is required per RS-485 standard.
How does the ST485ECN handle bus contention during power-up?
At power-on, all outputs default to high-impedance: driver outputs (A/B) and receiver output (RO) remain tri-stated until VCC stabilizes and control inputs (RE/DE) are actively driven. This prevents bus glitches and ensures clean initialization in systems with asynchronous power sequencing.
ST485ECN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- Through Hole
- Supplier Device Package:
- 8-DIP
ST485ECN FAQ
1.How can I place an order for ST485ECN through Aetrix?
Please submit a Request for Quotation (RFQ) for ST485ECN 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 ST485ECN reliable?
The price and inventory of ST485ECN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST485ECN is usually 5 days.
3.What payment methods are accepted for ST485ECN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST485ECN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ST485ECN?
ST485ECN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ST485ECN 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 ST485ECN?
For technical support, including ST485ECN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST485ECN requirements.
6.How does Aetrix verify that ST485ECN is sourced from the original manufacturer or authorized distributors?
All ST485ECN 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 ST485ECN meets industry standards.
7.What is the process for return or replacement of ST485ECN?
All ST485ECN units undergo pre-shipment inspection (PSI). If there is an issue with ST485ECN, 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 ST485ECN part is unused and in its original packaging.
Return procedure for ST485ECN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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