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STMicroelectronics ST485ERBDR
- Part No.:
- ST485ERBDR
- Manufacturer:
- STMicroelectronics
- Category:
- Drivers, Receivers, Transceivers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ST485ERBDR.pdf
- Description:
- IC TRANSCEIVER HALF 1/1 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,774
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Product details
Overview
ST485ERBDR from STMicroelectronics is a ±15 kV HBM ESD-protected, low-power RS-485/RS-422 half-duplex transceiver in SO8 package. It features 300 µA typical quiescent current, -7 V to +12 V common-mode input range, 30 ns driver propagation delay, 70 mV receiver hysteresis, and thermal shutdown protection. It enables robust industrial serial communication in multi-drop bus systems.
For engineers reviewing the ST485ERBDR datasheet, ST485ERBDR pinout, ST485ERBDR application, or ST485ERBDR equivalent, key selection criteria include ESD robustness (±15 kV HBM), bus node count support (64 transceivers), driver short-circuit protection, 2.5 Mbps max data rate, and SO8 footprint compatibility with legacy RS-485 designs.
Technical Context
The ST485ERBDR integrates one driver and one receiver optimized for half-duplex RS-485/RS-422 differential bus operation. Its driver supports current limiting and thermal shutdown under overload, while the receiver delivers 24 kΩ input resistance and 70 mV hysteresis for noise immunity across -7 V to +12 V common-mode voltage.
Control logic uses independent DE (driver enable) and RE (receiver enable) pins to manage direction and tri-state behavior. The device maintains high-impedance outputs when powered down or disabled, enabling hot-swap capability and bus arbitration in multi-node networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | Single 5 V ±5 % - eliminates need for auxiliary rails in 5 V systems |
| Quiescent Current | 300 µA typical - enables battery-backed or energy-constrained remote nodes |
| ESD Protection | ±15 kV HBM, ±8 kV IEC-1000-4-2 contact - reduces external TVS requirements |
| Max Data Rate | 2.5 Mbps - supports medium-speed industrial automation and building control protocols |
| Common-Mode Range | -7 V to +12 V - tolerates ground potential differences in long cable runs |
| Driver Propagation Delay | 30 ns typical - ensures timing margin for 2.5 Mbps operation with 54 Ω termination |
| Receiver Input Hysteresis | 70 mV typical - suppresses false triggering from EMI on noisy factory floors |
Pinout & Package
ST485ERBDR is housed in an SO8 (Small Outline 8-pin) package per ECOPACK® standards, with 1.27 mm pitch, 4.9 mm width, and 6.0 mm length. Pin 1 marked by notch or dot; lead-free and RoHS-compliant.
| 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 = disabled (high-Z), low = enabled |
| 3 DE | Driver enable (active high) | Controls driver activation; high = enabled, low = high-Z output state |
| 4 DI | Driver input | TTL/CMOS logic input accepting MCU UART TX signal |
| 5 GND | Ground reference | Signal and power return path shared by driver, receiver, and supply |
| 6 A | Non-inverting bus terminal | Connects to RS-485 bus A line; driver output and receiver input |
| 7 B | Inverting bus terminal | Connects to RS-485 bus B line; driver output and receiver input |
| 8 VCC | Positive supply | 5 V power input with internal regulation for stable biasing |
Key Features
| Feature | Design Value |
|---|---|
| Thermal shutdown protection | Automatically disables driver during overcurrent or overheating, preventing latch-up and permanent damage |
| Independent DE/RE control | Enables precise half-duplex timing control without shared direction pin, simplifying MCU GPIO allocation |
| High-impedance outputs on power-off | Prevents bus contention during power sequencing or brown-out conditions in multi-supply systems |
| 24 kΩ receiver input resistance | Reduces loading on terminated RS-485 bus, supporting up to 64 unit loads without signal degradation |
| 30 ns driver propagation delay | Meets setup/hold timing for 2.5 Mbps operation with standard 54 Ω differential termination |
Applications
| Industrial PLC Networks | Building Automation Systems |
|---|---|
Use Scenario: Multi-drop RS-485 bus connecting programmable logic controllers, I/O modules, and HMIs over distances up to 1200 m. IC Role / Device Role / Timing Role: Half-duplex transceiver managing bidirectional Modbus RTU traffic between master and slave nodes. Use Value: ±15 kV ESD protection prevents field failures in electrically noisy factory environments; -7 V to +12 V common-mode range accommodates ground offsets across distributed cabinets. | Use Scenario: Centralized HVAC controller communicating with thermostats, valve actuators, and sensor nodes via twisted-pair cabling. IC Role / Device Role / Timing Role: RS-485 interface IC translating UART signals to differential bus levels for BACnet MS/TP or LonWorks protocols. Use Value: 300 µA quiescent current extends battery life in wireless gateway bridges; 70 mV hysteresis rejects switching noise from nearby AC motors and relays. |
| Energy Metering Gateways | Remote Terminal Units (RTUs) |
Use Scenario: Smart meter concentrator aggregating consumption data from 32+ electricity meters using RS-485 daisy-chain topology. IC Role / Device Role / Timing Role: Bus node transceiver handling burst-mode DLMS/COSEM message exchanges at 9600–19200 bps. Use Value: 24 kΩ input resistance allows full 64-node capacity without bus re-termination; SO8 package enables compact PCB layout in space-constrained meter enclosures. | Use Scenario: Oil & gas pipeline monitoring RTU collecting pressure, flow, and valve status over 2 km RS-485 links in harsh outdoor conditions. IC Role / Device Role / Timing Role: Ruggedized physical layer interface ensuring reliable SCADA telemetry transmission in wide temperature (-40°C to +85°C) and high-EMI settings. Use Value: Thermal shutdown prevents driver failure during lightning-induced surges; ±8 kV IEC contact discharge rating meets EN 61000-4-2 Level 4 compliance. |
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+ | Lower quiescent current (120 µA), integrated slew-rate limiting, no thermal shutdown | Better suited for ultra-low-power battery nodes; lacks fault protection under sustained short-circuit | Select when power budget is critical and bus faults are mitigated externally |
| SN65HVD72DR | Higher ESD rating (±16 kV HBM), 500 kbps max data rate, no receiver hysteresis spec | Optimized for lower-speed, higher-noise environments like motor drives; reduced timing margin at 2.5 Mbps | Select when enhanced ESD margin outweighs speed requirement and hysteresis is managed system-level |
Compared with MAX13487EESA+ and SN65HVD72DR, ST485ERBDR uniquely balances 2.5 Mbps speed, ±15 kV ESD, thermal protection, and 300 µA quiescent current-making it optimal for industrial RS-485 nodes requiring both robustness and moderate throughput.
Availability
ST485ERBDR is available at Aetrix Electronics and suitable for industrial PLC networks, building automation systems, and remote terminal units requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for ST485ERBDR 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, delivering intelligent power, analog, MEMS, and microcontroller solutions for industrial, automotive, and consumer markets.
The ST485 series belongs to ST's industrial interface portfolio, designed specifically for ruggedized, ESD-hardened RS-485/RS-422 communication in factory automation, energy infrastructure, and building control systems.
FAQ
What is the maximum number of ST485ERBDR transceivers supported on a single RS-485 bus?
The ST485ERBDR supports up to 64 unit loads on one bus, based on its 24 kΩ receiver input resistance and compliance with TIA/EIA-485 standard load definitions. This allows direct connection of 64 devices without bus repeaters or impedance matching adjustments.
Does ST485ERBDR require external current-limiting resistors on the A/B lines?
No. The ST485ERBDR integrates driver current limiting and thermal shutdown circuitry, eliminating the need for external series resistors on A/B lines. External termination (120 Ω across A/B at bus ends) remains required for impedance matching and signal integrity.
Can ST485ERBDR operate with a 3.3 V supply?
No. ST485ERBDR is specified only for 5 V ±5 % operation per its absolute maximum ratings and electrical characteristics tables. Using 3.3 V results in undefined behavior, including insufficient driver output voltage and unreliable receiver thresholds.
How does the ST485ERBDR behave when VCC is removed while bus lines remain energized?
When VCC is removed, both driver and receiver outputs enter high-impedance states, preventing back-powering or bus contention. The A/B terminals remain protected by ±14 V absolute maximum ratings, allowing safe exposure to live bus voltages during hot-swap or partial power-down scenarios.
ST485ERBDR 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:
- 2.5Mbps
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
ST485ERBDR FAQ
1.How can I place an order for ST485ERBDR through Aetrix?
Please submit a Request for Quotation (RFQ) for ST485ERBDR 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 ST485ERBDR reliable?
The price and inventory of ST485ERBDR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST485ERBDR is usually 5 days.
3.What payment methods are accepted for ST485ERBDR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST485ERBDR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ST485ERBDR?
ST485ERBDR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ST485ERBDR 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 ST485ERBDR?
For technical support, including ST485ERBDR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST485ERBDR requirements.
6.How does Aetrix verify that ST485ERBDR is sourced from the original manufacturer or authorized distributors?
All ST485ERBDR 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 ST485ERBDR meets industry standards.
7.What is the process for return or replacement of ST485ERBDR?
All ST485ERBDR units undergo pre-shipment inspection (PSI). If there is an issue with ST485ERBDR, 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 ST485ERBDR part is unused and in its original packaging.
Return procedure for ST485ERBDR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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