The SN65HVD74DR is a Texas Instruments 3.3V RS-485 half-duplex transceiver with 1Mbps data rate, 1\/8 unit load (256 nodes), fail-safe receiver, and 16kV HBM ESD on bus pins. It features receiver equalization for extended cable reach. Packaged in SOIC-8, -40C to +85C.<\/p>\n
| \u0645\u0639\u062f\u0644 \u0627\u0644\u0628\u064a\u0627\u0646\u0627\u062a<\/td>\n | 1 Mbps<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||||||||
| Supply<\/td>\n | 3.3 V<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||||||||
| Mode<\/td>\n | Half-duplex<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||||||||
| Unit Load<\/td>\n | 1\/8 (256 nodes)<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||||||||
| ESD (bus pins)<\/td>\n | 16 kV HBM<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||||||||
| \u0627\u0644\u062d\u0632\u0645\u0629<\/td>\n | SOIC-8<\/td>\n<\/tr>\n<\/table>\n\u0627\u0644\u0645\u064a\u0632\u0627\u062a<\/h2>\n\u0627\u0644\u062a\u0637\u0628\u064a\u0642\u0627\u062a<\/h2>\nProduct Overview The SN65HVD74DR is a Texas Instruments 3.3V RS-485 half-duplex transceiver with 1Mbps data rate, 1\/8 unit load (256 nodes), fail-safe receiver, and 16kV HBM ESD on bus pins. It features receiver equalization for extended cable reach. Packaged in SOIC-8, -40C to +85C. Key Specifications Data Rate 1 Mbps Supply 3.3 V Mode Half-duplex […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[13,20],"tags":[],"chip_brand":[138],"class_list":["post-8818","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-interface-ics","chip_brand-ti"],"acf":{"brief_explanation":"3.3V RS-485 half-duplex, 1Mbps, 256 nodes, 16kV ESD, SOIC-8","date_code":"","package_case":"8-Pin SOIC (4.9 x 3.9 x 1.27 mm)","in_stock":11000,"datasheet":"https:\/\/www.ti.com\/lit\/ds\/symlink\/sn65hvd74.pdf","price":"$1.20 @ 1ku","product_introduction":"The SN65HVD74DR is a Texas Instruments 3.3V RS-485 half-duplex transceiver optimized for reliable communication over long cables in industrial networks. The 1Mbps data rate supports high-speed Modbus and BACnet protocols. The 1\/8 unit load specification allows up to 256 nodes on a single bus, exceeding the standard 32-node limit of full unit-load devices. The fail-safe receiver design guarantees a logic-high output when the bus is open, shorted, or idle, preventing false UART character detection. The receiver equalization feature extends cable reach by compensating for high-frequency signal attenuation on long cables, enabling reliable communication at 1Mbps over cable lengths that would otherwise require lower data rates. The 16kV HBM ESD protection on bus pins provides robust fault tolerance during hot-swap and field handling. The 3.3V supply eliminates the need for a 5V rail in 3.3V-only systems. Packaged in SOIC-8 rated for -40C to +85C.","working_principle":"The SN65HVD74 uses differential signaling on the A and B bus pins for noise-immune communication over long cables. The driver converts single-ended logic (D input) into a differential voltage between A and B pins, with the driver enable (DE) controlling output activation. The receiver converts the differential bus voltage back to single-ended logic (R output), with the receiver enable (RE) controlling receiver activation. In half-duplex mode, DE and RE are typically controlled together (DE = RE-bar) for direction switching. The fail-safe receiver biases the A\/B inputs so that an idle bus (no active driver) produces a differential voltage greater than -200mV, ensuring a logic-high on R. The receiver equalization adds a small amount of high-frequency boost to compensate for cable skin-effect attenuation, extending the usable cable length at 1Mbps. The 1\/8 unit load is achieved by limiting the bus input leakage current to less than 125uA (1\/8 of the 1mA full unit load standard).","pin_description":"
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