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STMicroelectronics ST490ACN
- Part No.:
- ST490ACN
- Manufacturer:
- STMicroelectronics
- Category:
- Drivers, Receivers, Transceivers
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
ST490ACN.pdf
- Description:
- IC TRANSCEIVER FULL 1/1 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,573
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Product details
Overview
ST490ACN from STMicroelectronics is a low-power, high-speed RS-485/RS-422 transceiver in full-duplex configuration with one driver and one receiver. It operates from a single 5 V supply, draws ≤5 mA supply current, supports up to 25 Mbps data rate, and features ±4 kV ESD protection and fail-safe receiver logic. It is used in industrial serial communication links requiring robust differential signaling over long cables.
For engineers reviewing the ST490ACN datasheet, ST490ACN pinout, ST490ACN application, or ST490ACN equivalent, key selection criteria include common-mode input range (–7 V to +12 V), input hysteresis (70 mV typ.), thermal shutdown protection, driver short-circuit current limiting, and fail-safe receiver behavior under open-circuit inputs.
Technical Context
The ST490ACN implements a true full-duplex RS-485/RS-422 interface with independent driver and receiver paths. Its driver provides differential output voltage ≥1.5 V into 54 Ω (RS-422) and includes current limiting plus thermal shutdown for fault resilience. The receiver incorporates fail-safe biasing and 70 mV typical hysteresis to reject noise near threshold.
It meets RS-485 electrical specifications for unit load (1/8 UL), supports –7 V to +12 V common-mode input range, and guarantees logic-high output when A and B inputs are open. Propagation delays are tightly controlled: tPLH/tPHL ≤30 ns (receiver), ≤16 ns (driver), with skew <3 ns in both paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | Single 5 V (4.5–5.5 V); enables direct integration with 5 V logic and microcontrollers without level-shifting. |
| Max Data Rate | 25 Mbps (typ.); supports high-speed industrial fieldbus and point-to-point serial links up to 100 m at full rate. |
| Common-Mode Range | –7 V to +12 V; ensures reliable operation in electrically noisy environments with ground potential differences. |
| Input Hysteresis | 70 mV (typ.); improves noise immunity on differential receiver inputs, reducing false toggling in marginal signal conditions. |
| ESD Protection | ±4 kV HBM; provides robustness against electrostatic discharge during handling and system integration. |
| Fail-Safe Receiver | Outputs logic high when A/B inputs are open or shorted; prevents undefined states in unterminated or disconnected bus segments. |
| Driver Short-Circuit Current | ±35 mA (min), ±250 mA (max); enables safe current limiting during bus faults without latch-up or damage. |
Pinout & Package
ST490ACN is housed in an 8-pin SOIC (SO-8) package with standard 1.27 mm pitch, RoHS-compliant and ECOPACK® certified. Pin numbering follows JEDEC MS-012, with exposed pad not present.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VCC | Power supply input | 5 V supply rail; requires local 0.1 µF decoupling capacitor adjacent to pin for stable high-speed operation. |
| 2 RO | Receiver output | CMOS-compatible logic output; drives standard TTL/CMOS loads with VOH ≥3.5 V @ –8 mA and VOL ≤0.4 V @ 8 mA. |
| 3 DI | Driver input | Logic-level input controlling driver state; VIH ≥2 V, VIL ≤0.8 V; compatible with 5 V microcontroller GPIOs. |
| 4 GND | Ground reference | Signal and power return path; must be connected to system ground plane with low-inductance routing. |
| 5 Y | Non-inverting driver output | Positive-side RS-485/422 differential output; pairs with Z to deliver ≥1.5 V differential swing into 54 Ω. |
| 6 Z | Inverting driver output | Negative-side RS-485/422 differential output; complements Y to form balanced transmission pair. |
| 7 B | Inverting receiver input | Complementary input to A; differential input impedance 12–24 kΩ; accepts –7 V to +12 V common-mode signals. |
| 8 A | Non-inverting receiver input | Primary receiver input; used with B to detect differential voltage ≥200 mV for valid logic transitions. |
Key Features
| Feature | Design Value |
|---|---|
| Low supply current | 5 mA max (unloaded or fully loaded); reduces system power budget and thermal load in dense multi-transceiver nodes. |
| Thermal shutdown protection | Automatically disables driver outputs into high-impedance state during overtemperature or sustained short-circuit events. |
| Fail-safe receiver | Guarantees RO = high when A and B are open, floating, or shorted - eliminates need for external bias resistors. |
| Tight propagation skew | tSKEW ≤3 ns (driver), tSKD ≤3 ns (receiver); preserves signal integrity in high-speed timing-critical applications like encoder feedback. |
| Robust ESD tolerance | ±4 kV HBM rating on all I/O pins; simplifies board-level ESD design and improves field reliability in industrial settings. |
Applications
| Industrial PLC Backplane | Factory Automation Sensor Hub |
|---|---|
Use Scenario: Serial backplane interconnect between CPU and I/O modules in modular PLC chassis using RS-422 point-to-point links. IC Role / Device Role / Timing Role: Full-duplex transceiver enabling simultaneous command upload and status reporting at 10–25 Mbps over 1–3 m traces. Use Value: Low propagation delay (≤16 ns driver, ≤30 ns receiver) and tight skew (<3 ns) ensure deterministic timing for real-time control loops. | Use Scenario: Aggregating analog and digital sensor data from multiple field devices (pressure, temperature, flow) into a central gateway via daisy-chained RS-485. IC Role / Device Role / Timing Role: Bus node transceiver with fail-safe receiver and ±7 V to +12 V common-mode range for noise-immune multi-drop communication. Use Value: Fail-safe logic high output prevents spurious resets during cable disconnection or EMI-induced bus floating. |
| Motor Drive Position Feedback | Building Management System (BMS) Controller |
Use Scenario: Transmitting high-resolution encoder position data from servo motor to motion controller over 10–30 m twisted-pair cable. IC Role / Device Role / Timing Role: High-speed RS-422 transceiver delivering 25 Mbps differential signaling with minimal jitter (<5%) for sub-microsecond timing resolution. Use Value: 70 mV input hysteresis rejects common-mode noise from PWM-driven motor windings, preserving data integrity. | Use Scenario: Interfacing HVAC controllers, lighting panels, and security subsystems across a building-wide RS-485 network operating at 19.2–115.2 kbps. IC Role / Device Role / Timing Role: Robust physical layer interface supporting long cable runs (up to 1200 m at lower rates) and multi-node topologies. Use Value: ±4 kV ESD protection and thermal shutdown enable reliable operation in uncontrolled environments with frequent human interaction and environmental stress. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar RS-485/RS-422 transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX485CSA+ | Lower max data rate (2.5 Mbps), no thermal shutdown, 250 µA quiescent current | Suitable for low-speed, low-power nodes; lacks fault protection for continuous bus shorts | Select when cost sensitivity outweighs speed/fault tolerance requirements |
| SN65HVD72DR | Higher ESD rating (±16 kV), 50 Mbps capability, integrated 120 Ω termination resistor option | Targeted at automotive and harsh industrial use; supports higher-speed upgrades and simplified layout | Select when future-proofing for >25 Mbps or enhanced ESD robustness is required |
Compared with MAX485CSA+ and SN65HVD72DR, the ST490ACN uniquely balances 25 Mbps performance, thermal fault protection, and fail-safe receiver behavior in a cost-effective SO-8 package - making it optimal for mid-speed industrial control nodes where reliability under intermittent fault conditions is critical.
Availability
ST490ACN is available at Aetrix Electronics and suitable for industrial PLC backplanes, factory automation sensor hubs, motor drive position feedback systems, and building management system controllers requiring stable component supply and long-term manufacturability.
Supply support for ST490ACN 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, power ICs, sensors, and analog/mixed-signal products for industrial, automotive, and consumer markets.
The ST490ACN belongs to ST's legacy RS-485/RS-422 transceiver product line, engineered specifically for robust, low-power, full-duplex serial communication in electrically noisy industrial environments.
FAQ
What is the maximum cable length supported by ST490ACN at 25 Mbps?
At 25 Mbps, ST490ACN supports up to 100 m over standard 120 Ω twisted-pair cable per the RS-422 specification. Performance depends on cable quality, termination, and noise environment; shorter lengths (≤30 m) are recommended for margin in electrically harsh settings.
Does ST490ACN require external bias or termination resistors?
No external bias resistors are needed due to its built-in fail-safe receiver. A 120 Ω termination resistor is required at the far end of the differential pair for impedance matching, but ST490ACN itself does not integrate termination - it relies on external placement per RS-485/422 layout best practices.
Can ST490ACN operate with a 3.3 V supply?
No. ST490ACN is specified only for 4.5–5.5 V operation. It lacks 3.3 V compatibility; attempting 3.3 V supply results in undefined behavior, insufficient driver output swing, and non-compliant receiver thresholds per RS-485 standards.
How does the thermal shutdown feature behave during a sustained bus short?
When driver output current exceeds safe limits (e.g., Y/Z shorted to GND or VCC), internal thermal sensing triggers shutdown within milliseconds, forcing both Y and Z into high-impedance state. Recovery occurs automatically after junction temperature falls below threshold, restoring normal operation without reset.
ST490ACN 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:
- Full
- Receiver Hysteresis:
- 70 mV
- Data Rate:
- 50Mbps
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-DIP
ST490ACN FAQ
1.How can I place an order for ST490ACN through Aetrix?
Please submit a Request for Quotation (RFQ) for ST490ACN 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 ST490ACN reliable?
The price and inventory of ST490ACN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST490ACN is usually 5 days.
3.What payment methods are accepted for ST490ACN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST490ACN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ST490ACN?
ST490ACN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ST490ACN 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 ST490ACN?
For technical support, including ST490ACN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST490ACN requirements.
6.How does Aetrix verify that ST490ACN is sourced from the original manufacturer or authorized distributors?
All ST490ACN 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 ST490ACN meets industry standards.
7.What is the process for return or replacement of ST490ACN?
All ST490ACN units undergo pre-shipment inspection (PSI). If there is an issue with ST490ACN, 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 ST490ACN part is unused and in its original packaging.
Return procedure for ST490ACN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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