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STMicroelectronics ST485EXDR
- Part No.:
- ST485EXDR
- Manufacturer:
- STMicroelectronics
- Category:
- Drivers, Receivers, Transceivers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ST485EXDR.pdf
- Description:
- IC TRANSCEIVER HALF 1/1 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:9,580
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Product details
Overview
ST485EXDR 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 -55 °C to +125 °C extended temperature range. It integrates one driver and one receiver for multipoint bus communication in industrial automation networks.
For engineers reviewing the ST485EXDR datasheet, ST485EXDR pinout, ST485EXDR application, or ST485EXDR equivalent, key selection criteria include common-mode voltage range (-7 V to +12 V), 5 Mbps maximum data rate, 30 ns typical propagation delay, and thermal shutdown protection for driver overload resilience.
Technical Context
The ST485EXDR implements a half-duplex transceiver architecture with independent enable controls: DE (driver enable) and RE (receiver enable), allowing precise bus direction control. Its differential A/B terminals support bidirectional signaling over long cables with 96 kΩ receiver input resistance and 70 mV input hysteresis for noise immunity.
Driver outputs feature short-circuit current limiting (35–250 mA) and thermal shutdown, forcing high-impedance state under fault conditions. Receiver output (RO) delivers TTL-compatible logic levels (VOH ≥ 3.5 V, VOL ≤ 0.4 V at 4 mA load) with 110–130 ns propagation delay and 5–10 ns skew.
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 - robust interface survivability in harsh industrial environments |
| Common-Mode Range | -7 V to +12 V - supports reliable communication across noisy ground potentials in factory-floor wiring |
| Max Data Rate | 5 Mbps - sufficient for high-speed PLC backplanes and motion control loops |
| Propagation Delay | 30 ns typ. (driver), 130 ns max. (receiver) - enables tight timing budgets in deterministic real-time networks |
| Input Hysteresis | 70 mV typ. - suppresses false triggering from EMI-induced signal ringing on long stubs |
| Receiver Input Resistance | 96 kΩ - allows up to 256 unit loads on shared RS-485 bus without termination compromise |
Pinout & Package
ST485EXDR is housed in an SO-8 (Small Outline, 8-pin) surface-mount package per ECOPACK® environmental compliance standards, with 1.27 mm pitch, 4.8–5.0 mm body width, and 3.8–4.0 mm body length.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 RO | Receiver output | TTL-level digital output reflecting differential A–B state; drives microcontroller GPIO or UART RX line |
| 2 RE | Receiver output enable | Active-low control: pulls RO to high-impedance when asserted, enabling bus sharing |
| 3 DE | Driver output enable | Active-high control: activates A/B driver only when asserted, preventing bus contention |
| 4 DI | Driver input | TTL-level digital input accepted directly from MCU TX or UART output without level translation |
| 5 GND | Ground reference | Signal return path for internal circuitry and external biasing; must be connected to local system ground |
| 6 A | Non-inverting bus terminal | Differential output (+) and input (+); connects to RS-485 bus A line with 120 Ω termination if end-node |
| 7 B | Inverting bus terminal | Differential output (–) and input (–); connects to RS-485 bus B line, polarity critical for correct data recovery |
| 8 VCC | Positive supply | 5 V power input with internal regulation; decoupling capacitor (100 nF) required within 1 cm of pin |
Key Features
| Feature | Design Value |
|---|---|
| Thermal shutdown protection | Automatically disables driver outputs during sustained overload, preventing latch-up or permanent damage |
| High-impedance driver disable | Driver outputs enter true high-Z state when DE = low or VCC = 0, eliminating bus leakage current |
| Wide common-mode tolerance | Supports ±7 V ground offset between nodes-critical for multi-chassis industrial systems with distributed grounding |
| Low-power idle mode | Draws only 300 µA with drivers disabled and receivers active-enables always-on monitoring in energy-constrained nodes |
| Robust ESD immunity | Withstands ±15 kV HBM shocks on A/B pins without functional disruption or parameter shift |
Applications
| Industrial PLC Backplane | Building Automation Sensors |
|---|---|
|
Use Scenario: Interconnecting I/O modules across DIN-rail-mounted PLC chassis using daisy-chained RS-485. IC Role / Device Role / Timing Role: Half-duplex transceiver managing bidirectional command/response traffic between master controller and slave modules. Use Value: -55 °C to +125 °C rating ensures reliability inside sealed enclosures exposed to ambient heat buildup; 96 kΩ input resistance supports >200 nodes per segment. |
Use Scenario: Connecting temperature, CO₂, and occupancy sensors to HVAC controllers via twisted-pair cabling in commercial buildings. IC Role / Device Role / Timing Role: RS-485 physical layer interface converting UART signals to differential bus signals for noise-immune transmission over 300+ meter runs. Use Value: ±15 kV HBM ESD protection prevents field failures during sensor installation/maintenance; 300 µA quiescent current extends battery life in wireless-sensor-hub configurations. |
| Motor Drive Feedback Network | Railway Signaling Interface |
|
Use Scenario: Transmitting position feedback and status telemetry from servo drives to central motion controller in CNC machinery. IC Role / Device Role / Timing Role: Isolated RS-485 node transceiver (used downstream of isolator) handling time-critical encoder updates and alarm reporting. Use Value: 5 Mbps capability supports high-resolution multi-turn encoder streaming; 70 mV hysteresis rejects switching noise from nearby IGBT gate drivers. |
Use Scenario: Linking trackside signal relays, axle counters, and interlocking units in EN 50121-compliant railway signaling systems. IC Role / Device Role / Timing Role: Ruggedized physical layer device enabling deterministic serial communication across electrically noisy rail corridors with large ground potential differences. Use Value: -7 V to +12 V common-mode range accommodates traction return currents; thermal shutdown prevents failure during lightning-induced surges on outdoor cable runs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar RS-485 transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX13487EESA+ | Same SO-8 package, 3.0–5.5 V supply range, 1/8-unit-load receiver input resistance (224 kΩ) | Enables >512 nodes per bus; lower supply flexibility limits use in fixed 5 V-only designs | Select when ultra-high node count is prioritized over strict 5 V-only compatibility |
| SN65HVD72DR | SO-8, 3.3 V supply only, ±16 kV ESD, integrated 120 Ω termination resistor | Reduces BOM count in space-constrained nodes but incompatible with 5 V systems | Select for new 3.3 V designs where board area savings outweigh voltage constraint |
Compared with MAX13487EESA+ and SN65HVD72DR, ST485EXDR uniquely combines 5 V operation, extended temperature range (-55 °C to +125 °C), and proven industrial field reliability-making it optimal for legacy 5 V infrastructure upgrades and high-ambient-temperature deployments.
Availability
ST485EXDR is available at Aetrix Electronics and suitable for industrial PLC backplanes, building automation sensor networks, motor drive feedback links, and railway signaling interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for ST485EXDR 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, mixed-signal, power, and microcontroller 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 and thermal environments.
FAQ
What is the maximum number of ST485EXDR transceivers supported on a single RS-485 bus?
The ST485EXDR features a 1/4-unit-load receiver input resistance of 96 kΩ, enabling up to 256 transceivers on a single terminated RS-485 bus. This assumes standard 120 Ω termination at both ends and no additional loading from bias resistors or other devices. Bus capacitance and stub length must remain within TIA/EIA-485-A limits to maintain signal integrity at 5 Mbps.
Does ST485EXDR require external current-limiting resistors on the A/B lines?
No. The ST485EXDR integrates driver current limiting and thermal shutdown circuitry, eliminating the need for external current-limiting resistors on A/B lines. External 120 Ω termination resistors are required at the two physical ends of the bus, and optional bias resistors (e.g., 560 Ω pull-up on A, pull-down on B) may be added for fail-safe idle-state detection.
Can ST485EXDR operate reliably with ground potential differences exceeding 5 V between nodes?
Yes. ST485EXDR supports a -7 V to +12 V common-mode input voltage range, allowing up to 19 V total ground potential difference between any two nodes. This capability is essential in multi-chassis industrial systems where ground references differ due to long cable runs, motor drive noise, or separate power domains.
Is ST485EXDR pin-compatible with earlier ST485 variants like ST485BD or ST485CD?
Yes. ST485EXDR shares identical SO-8 pinout, electrical behavior, and functional truth tables with ST485EBDR and ST485ECDR. The primary distinction is its extended -55 °C to +125 °C operating temperature range, making it a direct drop-in replacement in thermally demanding applications where standard-grade variants would derate or fail.
ST485EXDR 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:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
ST485EXDR FAQ
1.How can I place an order for ST485EXDR through Aetrix?
Please submit a Request for Quotation (RFQ) for ST485EXDR 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 ST485EXDR reliable?
The price and inventory of ST485EXDR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST485EXDR is usually 5 days.
3.What payment methods are accepted for ST485EXDR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST485EXDR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ST485EXDR?
ST485EXDR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ST485EXDR 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 ST485EXDR?
For technical support, including ST485EXDR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST485EXDR requirements.
6.How does Aetrix verify that ST485EXDR is sourced from the original manufacturer or authorized distributors?
All ST485EXDR 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 ST485EXDR meets industry standards.
7.What is the process for return or replacement of ST485EXDR?
All ST485EXDR units undergo pre-shipment inspection (PSI). If there is an issue with ST485EXDR, 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 ST485EXDR part is unused and in its original packaging.
Return procedure for ST485EXDR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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