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Analog Devices Inc./Maxim Integrated MAX3140CEI+
- Part No.:
- MAX3140CEI+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Controllers
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MAX3140CEI+.pdf
- Description:
- IC UART SPI MICRWR W/TXRX 28QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,230
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Product details
Overview
The MAX3140CEI+ from Maxim Integrated is a single-chip SPI/MICROWIRE-compatible UART with integrated true fail-safe RS-485/RS-422 transceiver in a 28-pin QSOP package. It delivers UART functionality (up to 230 kbaud, 8-word FIFO, 9-bit address recognition) and RS-485/RS-422 physical layer support (115 kbps / 500 kbps / 10 Mbps slew-rate programmable modes, ±13 V receiver input tolerance, 1/8-unit-load input impedance) for industrial serial communication systems requiring space-constrained, low-power, fault-tolerant connectivity.
For engineers reviewing the MAX3140CEI+ datasheet, MAX3140CEI+ pinout, MAX3140CEI+ application, or MAX3140CEI+ equivalent, this device addresses critical design needs in embedded RS-485 networks - including hardware shutdown (20 µA), twisted-pair polarity correction via TXP/RXP pins, independent half/full-duplex configuration, and fail-safe receiver behavior under open/shorted bus conditions - without external termination or microcontroller I/O overhead.
Technical Context
The MAX3140CEI+ integrates two functionally isolated subsystems: an SPI/QSPI/MICROWIRE-synchronous UART core (with crystal-derived oscillator, software-programmable baud generator, and interrupt-controlled 8-word receive FIFO) and a robust RS-485/RS-422 transceiver (featuring pin-selectable slew rate, true fail-safe receiver with guaranteed logic-high output on open/shorted inputs, and independent transmitter/receiver phase control). Both share only VCC and GND connections.
Its dual-mode operation enables flexible deployment: UART-only mode (e.g., local diagnostics), transceiver-only mode (e.g., legacy RS-485 node), or combined mode (e.g., intelligent remote sensor node). SRL, H/F, TXP, and RXP pins provide hardware-level configuration of data rate, duplex mode, and differential polarity - eliminating firmware dependency for basic network topology changes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | +4.75V to +5.25V - operates from standard 5V rail; no level-shifting required for TTL/CMOS host interfaces. |
| UART Max Baud Rate | 230 kbaud - supports high-speed asynchronous serial links with 3.6864 MHz crystal; sufficient for industrial telemetry and point-of-sale protocols. |
| RS-485 Data Rates | 115 kbps / 500 kbps / 10 Mbps - selectable via SRL pin; enables EMI-optimized low-speed or high-throughput full-duplex operation. |
| Receiver Input Impedance | 1/8-unit load - allows up to 256 nodes on a single RS-485 bus, supporting large-scale distributed control networks. |
| Fail-Safe Receiver | Guarantees logic-high RO when A–B is open or shorted - eliminates need for external bias resistors or termination monitoring circuitry. |
| Shutdown Current | 20 µA - achieved by driving SHDN low; preserves battery life in portable or energy-harvested edge devices. |
| Operating Temp Range | 0°C to +70°C - qualified for commercial/industrial indoor environments (MAX3140CEI+ suffix). |
Pinout & Package
Package: 28-pin QSOP (0.154" wide), RoHS-compliant, lead-free.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| X1, X2 | UART crystal oscillator inputs | X1 accepts 3.6864 MHz crystal or external clock; X2 left unconnected for crystal mode - enables precise baud timing without PLL. |
| DIN, DOUT, SCLK, CS | SPI/MICROWIRE interface | Full-duplex 16-bit synchronous serial port; Schmitt-trigger inputs tolerate noisy board traces; DOUT high-impedance when CS high. |
| DE, RE | RS-485 driver/receiver enable | Independent control: DE high enables Y/Z outputs; RE low enables RO - supports half/full-duplex and shutdown (DE=low, RE=high). |
| H/F, SRL, TXP, RXP | Hardware configuration pins | H/F selects duplex mode; SRL sets data rate; TXP/RXP invert differential polarity - enables field-reconfigurable bus topology without firmware update. |
| A, B, Y, Z | RS-485 differential I/O | A/B are full-duplex receiver inputs (1/8-unit load); Y/Z serve as driver outputs and half-duplex receiver inputs - simplifies 2-wire vs. 4-wire wiring. |
| IRQ, RTS, CTS, RX, TX | UART control & data signals | Standard UART handshaking (RTS/CTS), interrupt-driven RX/TX, and open-drain IRQ for priority-based MCU servicing. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated UART + RS-485 transceiver | Reduces BOM count and PCB area vs. discrete UART + transceiver solution; eliminates interconnect routing complexity and signal integrity risks. |
| True fail-safe receiver | Guarantees logic-high RO during bus faults - prevents spurious MCU interrupts or state corruption in HVAC, building control, and PLC applications. |
| Software-selectable UART features | Configurable baud rate (300–230k), 9-bit address recognition, and four-maskable interrupt sources - enables adaptive protocol handling in multi-drop networks. |
| Pin-programmable RS-485 modes | H/F, SRL, TXP, RXP pins allow hardware-defined duplex, speed, and polarity - supports factory-set or field-upgraded network configurations without code changes. |
| 20 µA hardware shutdown | SHDN pin disables UART oscillator and transceiver bias - extends battery life in portable instrumentation and wireless gateway edge nodes. |
| 1/8-unit-load receiver input | Enables >250-node RS-485 buses - meets scalability requirements for large-scale industrial automation and smart metering infrastructure. |
Applications
| Industrial Automation | HVAC & Building Control |
|---|---|
Use Scenario: Distributed I/O modules communicating over long RS-485 daisy chains in factory-floor PLC networks. IC Role / Device Role / Timing Role: UART handles Modbus ASCII/RTU framing; RS-485 transceiver provides ESD-hardened, fail-safe physical layer for noisy 100+ meter runs. Use Value: Eliminates external termination and biasing components; 1/8-unit-load input supports 256-node scalability without repeaters. |
Use Scenario: Smart thermostats and zone controllers exchanging setpoints and sensor data across building-wide RS-485 backbone. IC Role / Device Role / Timing Role: SPI interface connects to low-pin-count MCU; fail-safe receiver prevents lockup during cable disconnection or lightning-induced transients. Use Value: Hardware-configurable H/F and SRL pins allow pre-programmed 500 kbps full-duplex operation - reduces firmware validation effort across product variants. |
| Point-of-Sale Terminals | Intelligent Instrumentation |
Use Scenario: Compact POS terminals interfacing with receipt printers, barcode scanners, and cash drawers via RS-485 peripherals. IC Role / Device Role / Timing Role: UART manages asynchronous command/response protocol; transceiver drives multiple peripherals on shared bus with polarity correction (TXP/RXP). Use Value: 8-word FIFO minimizes CPU polling overhead; 20 µA shutdown extends battery backup runtime during power outages. |
Use Scenario: Portable test equipment (e.g., multimeters, oscilloscopes) transmitting measurement data to PC hosts over RS-485 cables. IC Role / Device Role / Timing Role: Crystal-based UART ensures accurate timing for high-precision timestamping; true fail-safe behavior maintains host link integrity during probe disconnects. Use Value: Single 5V supply simplifies power design; 28-pin QSOP footprint fits tight enclosures without sacrificing debug or upgrade flexibility. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar UART + RS-485 transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX3140EEI+ | Same silicon, extended temperature range (–40°C to +85°C); identical pinout, electrical specs, and feature set. | Required for outdoor, automotive under-hood, or uncontrolled-environment deployments where ambient exceeds 70°C. | Select MAX3140EEI+ when operating temperature exceeds 0°C to +70°C; otherwise MAX3140CEI+ is cost-optimized for commercial-grade indoor use. |
| MAX3100CEE+ | UART-only IC (no integrated transceiver); SPI interface, 230 kbaud, 8-word FIFO, same 28-pin QSOP package and register map. | Used when RS-485 transceiver is already present or implemented separately (e.g., with MAX3089 or SN65HVD72). | Choose MAX3100CEE+ if transceiver selection must be decoupled (e.g., for voltage-level translation, higher ESD rating, or alternate bus topology). |
Compared with MAX3140EEI+, the MAX3140CEI+ offers identical functionality at lower cost for ambient-temperature-limited applications; compared with MAX3100CEE+, it adds integrated RS-485 transceiver capability - reducing component count, layout area, and qualification effort for new RS-485 node designs.
Availability
MAX3140CEI+ is available at Aetrix Electronics and suitable for industrial automation, HVAC control, and point-of-sale systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.
Supply support for MAX3140CEI+ 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
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in precision analog, mixed-signal, and high-reliability interface solutions for industrial, communications, and computing markets.
The MAX3140 belongs to Maxim's high-integration serial interface product line, designed to consolidate UART, transceiver, and configuration logic into minimal-footprint solutions for noise-immune, multi-drop industrial communication.
FAQ
What is the maximum UART baud rate supported by the MAX3140CEI+?
The MAX3140CEI+ supports UART data rates up to 230 kbaud when using a 3.6864 MHz crystal. This is achieved through its software-programmable baud-rate generator with integer and fractional divider ratios. The actual achievable rate depends on crystal accuracy and system clock stability - typical operation at 115.2 kbaud is robust across temperature and voltage variations. The MAX3140CEI+ does not require external clock multiplication to reach this rate.
How does the true fail-safe receiver in the MAX3140CEI+ improve system reliability?
The true fail-safe receiver in the MAX3140CEI+ guarantees a logic-high output on RO when the A–B differential input is open-circuited or shorted - a common failure mode in RS-485 cabling. This prevents spurious low-level signals from triggering false UART interrupts or corrupting MCU state. Unlike basic fail-safe implementations relying on weak internal biasing, the MAX3140CEI+ uses dedicated circuitry that meets TIA/EIA-485 requirements without external resistors.
Can the MAX3140CEI+ operate in both half-duplex and full-duplex RS-485 modes?
Yes, the MAX3140CEI+ supports both modes via the H/F pin: connect H/F to VCC for half-duplex (2-wire bus, shared Y/Z for transmit/receive), or leave H/F unconnected or tied to GND for full-duplex (4-wire bus, dedicated A/B inputs and Y/Z outputs). The transceiver automatically adapts drive strength and receiver termination accordingly - no register writes or timing delays are needed to switch modes.
What is the purpose of the TXP and RXP pins on the MAX3140CEI+?
The TXP (transmitter phase) and RXP (receiver phase) pins on the MAX3140CEI+ allow hardware-level inversion of differential signal polarity. Connecting TXP or RXP to VCC flips the Y/Z or A/B logic mapping - correcting for reversed twisted-pair wiring in installed RS-485 cabling without requiring firmware changes or physical rewiring. This is especially valuable in field-deployed systems where cable polarity errors are difficult to diagnose and correct.
Does the MAX3140CEI+ require external components for basic RS-485 operation?
No external components are required for basic RS-485 operation with the MAX3140CEI+. Its true fail-safe receiver eliminates the need for external bias resistors; the 1/8-unit-load input impedance removes termination resistor constraints; and the integrated UART obviates external level shifters or clock generators. Only a 3.6864 MHz crystal (X1/X2), bypass capacitor on VCC, and optional TVS diodes for enhanced ESD protection are recommended for robust deployment.
MAX3140CEI+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package/Case:
- 28-SSOP (0.154", 3.90mm Width)
- Programmable:
- Not Verified
- Protocol:
- RS232, RS485
- Function:
- Controller
- Interface:
- SPI, UART
- Standards:
- -
- Voltage - Supply:
- 4.75V ~ 5.25V
- Current - Supply:
- 640µA
- Operating Temperature:
- 0°C ~ 70°C
- Supplier Device Package:
- 28-QSOP
- Grade:
- -
- Qualification:
- -
MAX3140CEI+ FAQ
1.How can I place an order for MAX3140CEI+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX3140CEI+ 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 MAX3140CEI+ reliable?
The price and inventory of MAX3140CEI+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX3140CEI+ is usually 5 days.
3.What payment methods are accepted for MAX3140CEI+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX3140CEI+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX3140CEI+?
MAX3140CEI+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX3140CEI+ 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 MAX3140CEI+?
For technical support, including MAX3140CEI+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX3140CEI+ requirements.
6.How does Aetrix verify that MAX3140CEI+ is sourced from the original manufacturer or authorized distributors?
All MAX3140CEI+ 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 MAX3140CEI+ meets industry standards.
7.What is the process for return or replacement of MAX3140CEI+?
All MAX3140CEI+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX3140CEI+, 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 MAX3140CEI+ part is unused and in its original packaging.
Return procedure for MAX3140CEI+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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