MAX485 RS-485 Transceiver ICs and UART Converter Modules

MAX485 components and RS-485 converter boards: select the actual function

This collection contains loose MAX485-family RS-485 transceiver ICs in DIP-8 and SOP-8 formats, assembled TTL-UART-to-RS-485 modules, automatic-direction boards, USB-to-RS-485 converters and selectable alternatives such as MAX3485, MAX487, MAX13487, SP485 and SP3485. It also includes multi-model IC listings, genuine mixed assortments and some products whose titles mention MAX485 but whose selected variant can be a different chip or accessory. “MAX485” in a collection name does not mean every item is a bare MAX485 IC or shares the same voltage, pinout, data rate, driver control, isolation, protection or included parts. Review the selected variant and product packing information before designing a board or purchasing spares.

What a half-duplex RS-485 transceiver actually does

A conventional MAX485-type transceiver translates between logic-level transmit/receive signals and a differential two-wire RS-485 physical bus. It is a physical-layer device, not a USB bridge, UART controller, Modbus processor, protocol converter or complete industrial network. The UART host defines baud rate, data format and application messages; the transceiver handles electrical transmit/receive on the bus. In a conventional half-duplex design the driver and receiver have control inputs, often called DE and active-low RE. Direction control must be coordinated with the final transmitted bit and any bus turnaround interval. A board described as “automatic flow” or “auto direction” may instead provide its own direction-control circuit; the mechanism and turnaround behavior depend on that board, not on the MAX485 name.

RS-485 is a differential electrical interface. A and B markings are not completely consistent among equipment vendors; check the actual device and board documentation rather than relying on a universal polarity mnemonic. Design a defined idle state, topology, termination and biasing strategy for the complete network. A nominal bus-node count or maximum cable length in a seller description is not a guarantee for every cable, data rate, transceiver loading or installation. Unit load, common-mode range, ESD/transient exposure, cable routing and ground-potential differences matter. RS-485 transceivers are not intrinsically galvanically isolated: if isolation is needed, verify that the chosen assembled product includes both an isolation barrier and an appropriate isolated power arrangement with documented working ratings.

Loose MAX485 ICs versus assembled modules

Loose IC options identify MAX485CPA/EPA and other DIP-8 codes, plus MAX485ESA/CSA SOP-8 surface-mount choices. Several listings offer 5, 10, 20, 100, 200 or 500 pieces of a selected device; piece count is not a supply-voltage or performance rating. DIP-8 and SOP-8 require different PCB footprints. Compare complete manufacturer suffix, temperature range, package dimensions, pin-one orientation, truth table, recommended supply, bus input/output characteristics, driver-enable polarity and thermal limits using the datasheet for the exact part actually shipped. Supplier terms such as “original,” “imported” and “new” are source-listing claims, not independent authentication or production-lot traceability.

Assembled MAX485 modules often provide logic-side UART/control pins and an A/B screw terminal, with some descriptions mentioning a 5.08 mm two-position terminal. These products are boards, not eight-pin ICs, and their regulators, terminal layout, pull resistors, transient protection and direction-control circuitry vary. A “5V module” claim should be checked on the selected board: the module supply and logic input-high threshold are distinct considerations. Do not assume a 5 V MAX485 board is safe for direct connection to a 3.3 V host or that its A/B terminals are protected against arbitrary field voltage. Conversely, a selected 3.3 V MAX3485 module is not proof that a 5 V MAX485 IC itself runs correctly at 3.3 V.

Alternative transceivers are not automatic drop-in replacements

Some Color choices explicitly distinguish “MAX485-5V-UNI,” “MAX3485-3V3-UNI,” “MAX13487-5V-BI” and “MAX13488-5V-BI.” Those names refer to different selected assembled boards and source-described direction behavior, not switch settings on one universal device. Other choices offer MAX485 versus SP485, or MAX485/MAX3485/SP3485/MAX13487 with separate 1-, 5-, 10- or 100-piece quantities. Compare actual supply, logic thresholds, driver-control requirements, failsafe receiver behavior, slew-rate characteristics, maximum data rate, unit-load class, ESD protection and pinout for the chosen exact code. A board advertised as bidirectional or automatic-control may use a different circuit from a manually controlled MAX485 module. Do not substitute by matching only the “485” substring.

Multi-model loose-chip listings also name MAX483, MAX487, MAX488, MAX489, MAX490, MAX491, MAX1487, MAX3082 and MAX13085 alongside MAX485. Some of these are different half-duplex or full-duplex parts, packages or speed classes; compare bus-wire count, receiver/driver enable, pin layout and supply rather than assuming a universal DIP-8/SOP-8 replacement. MAX202, MAX232 and MAX3232 are RS-232 interface parts, not RS-485 transceivers. A Color dropdown selecting MAX232 or MAX3232 does not deliver a MAX485, even when a title contains both families. Other cross-listed codes such as MAX705/MAX813 supervisors, MAX471/MAX472 current monitors, unrelated power ICs, transistors and memory chips are not serial-bus transceivers. A ten-piece multi-code title ordinarily needs its selected model and quantity checked; only a listing with an actual per-part packing list should be described as an assortment.

USB converters and mixed-interface boards

USB-to-RS-485 adapter listings mention FT232RL, CH340G, SP485 or MAX485 in different combinations; the USB bridge and the differential bus transceiver have separate jobs. A USB-to-TTL adapter alone does not supply RS-485 A/B signaling. Some USB boards advertise both UART/TTL and RS-485 functions, or RS-232 and RS-485 together, and one offers a 5 V-to-12 V boost function as well. Verify the selected board's actual populated circuits, connector pinout, output supply and host-driver support. An advertised operating-system list in a seller title is not a verified lifetime driver-support promise. Likewise “CAN to serial” in a broad title does not make a MAX485 module a CAN controller or CAN transceiver; CAN uses a different physical and protocol architecture.

Industrial converters may mention TVS protection and isolation. TVS parts alone do not provide galvanic isolation; an “isolated” title needs board-level evidence of the barrier, isolated power, ratings and installation conditions. Do not extend any board's protection claim to loose MAX485 chips or other modules. Distinguish USB, logic-level UART, RS-232, RS-485 and CAN explicitly when specifying both ends of a link. An adapter with a USB host connector generally requires host-side software and driver support; a bare transceiver soldered to an MCU board does not enumerate as a USB serial port.

Conflicting or low-confidence listings

Some products titled as MAX485/MAX3485 “voltage regulator” or “overvoltage protection” have descriptions referring to speakers, colors and dimensions unrelated to a normal transceiver module. Those fields are inconsistent, so do not rely on the title alone as proof of an RS-485 PCB, a voltage regulator or a safety protection rating. Check the actual product photos, selected variant, pin legend and included item before purchase. Listings claiming operation at very broad temperature ranges, 1200 m cable runs, 2.5 Mbit/s or fixed multidrop node counts are supplier statements about particular products or conditions, not collection-wide verified performance. The physical-layer datasheet and system-level link budget are the correct basis for engineering limits.

Engineering selection checklist

Pick the delivered form: loose DIP-8/SOP-8 transceiver, assembled MCU-side UART board, automatic-direction module, USB interface adapter, full conversion board or actual mixed IC kit.
Confirm the selected device: MAX485, MAX3485, MAX13487, SP485, SP3485, MAX487 or a different code can be selected within one listing. Check suffix, footprint and ordered piece count.
Match the logic domain: compare recommended VCC, input thresholds, receiver output levels and MCU I/O limits, rather than equating “3.3V/5V” in a title with universal compatibility.
Plan the bus: assess two-wire versus four-wire requirements, differential polarity from actual board markings, cable impedance, endpoint termination, idle bias, transceiver loading and reference/ground strategy.
Plan timing: determine whether DE/RE are host-controlled or board-controlled; validate turn-around at the intended baud rate and message format, including the final stop bit.
Validate resilience: inspect actual ESD/TVS provision and any isolation barrier, working voltage and isolated-power implementation for the chosen assembled product.
Check the order: a selected 10PCS chip code is not necessarily a ten-type kit, and a module with a screw terminal is not interchangeable with a loose SOIC device.

Frequently asked questions

Is a MAX485 the same as a USB-to-RS-485 adapter?

No. A MAX485-type IC is a bus transceiver. A USB adapter also needs a USB bridge and supporting board circuitry; confirm which assembled hardware the selected option includes.

Can I use a MAX485 module directly on a 3.3 V MCU?

Do not assume so. Compare the module's actual supply and logic-side levels with the MCU's guaranteed input/output specifications. A 3.3 V MAX3485 option is a different selected product.

Does automatic direction control mean Modbus works automatically?

No. Direction control is only a physical-layer transmit/receive detail. UART framing, Modbus addressing, timing and software implementation still need to match the connected devices.

Do MAX485 and MAX232 do the same job?

No. MAX485 is associated with differential RS-485 signaling, whereas MAX232-family choices are RS-232 interface devices. Check the selected model and connector-side electrical standard.

Is RS-485 wiring universally A-to-A and B-to-B?

Labels may be defined differently by equipment makers. Use actual product documentation to identify differential polarity and required common reference before designing the installation.

Will every listing reach 1200 meters or support 32 devices?

No collection-wide guarantee. These figures, where present, are source claims under particular conditions; real limits depend on cable, rate, loading, topology, biasing, protection and chosen transceiver.