描述 Description

The MAX3140 is a complete universal asynchronous receiver-transmitter (UART) and a true fail-safe RS-485/RS-422 transceiver combined in a single 28-pin QSOP package for space-, cost-, and power-constrained applications. The MAX3140 saves additional board space as well as microcontroller (μC) I/O pins by featuring an SPI?/QSPI?/MICROWIRE?-compatible serial interface. It is pin-programmable for configuration in all RS-485/RS-422 networks.
The MAX3140 includes a single RS-485/RS-422 driver and receiver featuring true fail-safe circuitry, which guarantees a logic-high receiver output when the receiver inputs are open or shorted. This feature provides immunity to faults without requiring complex termination. The MAX3140 provides software-selectable control of half- or full-duplex operation, data rate, slew rate, and transmitter and receiver phase. The RS-485 driver slew rate is programmable to minimize EMI and results in maximum data rates of 115kbps, 500kbps, and 10Mbps. Independent transmitter/receiver phase control enables software correction of twisted-pair polarity reversal. A 1/8-unit-load receiver input impedance allows up to 256 transceivers on the bus.
The MAX3140's UART includes an oscillator circuit derived from an external crystal, and a baud-rate generator with software-programmable divider ratios for all common baud rates from 300 baud to 230k baud. The UART features an 8-word-deep receive FIFO that minimizes processor overhead and provides a flexible interrupt with four maskable sources, including address recognition on 9-bit networks. Two control lines are included for hardware handshaking-one input and one output.
The MAX3140 operates from a single +5V supply and typically consumes only 645μA with the receiver active. Hardware-invoked shutdown reduces supply current to only 20μA. The UART and RS-485/RS-422 functions can be used together or independently since the two functions share only supply and ground connections (the MAX3140 is hardware- and software-compatible with the MAX3100 and MAX3089).

特性 Features

? Integrated UART and RS-485/RS-422 Transceiver in a Single 28-Pin QSOP
? SPI/MICROWIRE-Compatible Interface Saves μC I/O Pins
? True Fail-Safe Receiver Output Eliminates Complex Network Termination
? Pin-Programmable RS-485/RS-422 Features
? Half/Full-Duplex Operation
? Slew-Rate Limiting for Reduced EMI
? 115kbps/500kbps/10Mbps Data Rates
? Receiver/Transmitter Phase for Twisted-Pair Polarity Reversal
? Full-Featured UART
? Programmable Up to 230k baud with a 3.6864MHz Crystal
? 8-Word Receive FIFO Minimizes Processor Overhead
? 9-Bit Address-Recognition Interrupt
? Allows Up to 256 Transceivers on the Bus
? Low 20μA Hardware Shutdown Mode
? Hardware/Software-Compatible with MAX3100 and MAX3089

應(yīng)用 Application

? 嵌入式系統(tǒng)
? HVAC與樓宇控制
? 工業(yè)控制局域網(wǎng)
? 智能儀表
? 銷售終端機(jī)(POS)設(shè)備
? 用于EMI敏感應(yīng)用的收發(fā)器

簡(jiǎn)介

MAX3140屬于集成電路（IC）的控制器。由制造生產(chǎn)的MAX3140控制器該系列產(chǎn)品主要用于在采用不同通信協(xié)議和/或信令方法的端點(diǎn)之間提供信息連接。示例包括將 I2C 總線連接到 UART，將 USB 連接到 I2C、SPI、以太網(wǎng)或 UART、以太網(wǎng) MAC 和 PHY 等的器件。此外，還包括用于通過(guò)為點(diǎn)對(duì)點(diǎn)通信設(shè)計(jì)的接口建立多路連接的器件，例如 USB 集線器控制器。