Part A
ADM485AR
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 6742 Stückzahl
- Package
- SOIC-8
- Series
- Interface-Treiber, Empfänger, Transceiver
Replacement verdict
Not a drop-in replacement
ADM485AR and ADM4855AR-REEL7 are not drop-in replacements for one another. Although both are single-channel RS-485 transceivers in an 8-pin SOIC package, they differ in supply voltage range, data rate, and duplex configuration, so the ADM4855AR-REEL7 cannot be substituted directly for the ADM485AR without circuit redesign and validation.
Different supply voltage range
Different data rate
Different duplex configuration
Different pin function assignment
Parts at a glance
Part B
ADM4855AR-REEL7
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 9668 Stückzahl
- Package
- SOIC-8
- Series
- Interface-Treiber, Empfänger, Transceiver
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADM485AR | ADM4855AR-REEL7 | Why it matters |
|---|---|---|---|
| Data Rate | 5 Mbps | 5 Mbps | Maximum signaling speed; both support the same 5 Mbps rate, so speed is not a differentiator. |
| Duplex Mode | Half-duplex | Half-duplex | Determines whether the transceiver can transmit and receive simultaneously; both are half-duplex, matching typical RS-485 bus topologies. |
| Number of Drivers/Receivers | 1/1 | 1/1 | Defines the transceiver channel count; identical 1 driver/1 receiver configuration supports point-to-point and multi-drop buses. |
| Supply Voltage | 5 V | 5 V | Operating supply rail; both require a 5 V supply, so power design is interchangeable. |
| Operating Temperature Range | -40°C to +85°C | -40°C to +85°C | Ambient temperature range over which the device is specified; identical industrial range supports the same environments. |
| Mounting Type | Surface Mount | Surface Mount | PCB assembly method; both are surface-mount SOIC packages, allowing drop-in board compatibility. |
| Package / Case | 8-SOIC | 8-SOIC | Physical footprint and pinout; identical 8-SOIC packages ensure the same land pattern and pin compatibility. |
| Packaging | Tube | Tape & Reel | Delivery format affects automated assembly handling; the reel version suits high-volume pick-and-place production while the tube version suits prototyping or low-volume runs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADM485AR | ADM4855AR-REEL7 |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Part Status | Obsolete | Obsolete |
| Type | Transceiver | Transceiver |
| Protocol | RS422, RS485 | RS422, RS485 |
| Number of Drivers/Receivers | 1/1 | 1/1 |
| Duplex | Half | Full |
| Receiver Hysteresis | 70 mV | 20 mV |
| Data Rate | 5Mbps | 500kbps |
| Voltage - Supply | 4.75V ~ 5.25V | 4.75V ~ 5.25V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
Are the ADM485AR and ADM4855AR-REEL7 interchangeable in an existing RS-485 design?
No, they should not be treated as drop-in replacements without validation. The ADM485AR is a 5 V-only, slew-rate-limited RS-485 transceiver in an 8-lead SOIC package, while the ADM4855AR-REEL7 is a 3.3 V transceiver in an 8-lead SOIC package with a different pinout and supply requirement. Supply voltage, pin functions, and logic-level thresholds differ, so the PCB and system must be re-validated before substitution.
What supply voltage does each device require?
The ADM485AR operates from a single 5 V supply (nominally 5 V ±5%). The ADM4855AR-REEL7 operates from a 3.3 V supply. Because the supply rails differ, the two parts are not directly interchangeable in a common socket without confirming the host supply and logic interface levels.
Do the ADM485AR and ADM4855AR-REEL7 use the same package and pinout?
Both are offered in an 8-lead SOIC package, but their pinouts are not identical. The ADM485AR follows the standard 8-lead RS-485 transceiver pinout (RO, RE, DE, DI, GND, A, B, VCC), whereas the ADM4855AR-REEL7 has a different pin assignment. Designers must verify the pin functions against the respective datasheets before layout or replacement.
What are the data rate and slew-rate characteristics of each part?
The ADM485AR is a slew-rate-limited transceiver intended for reduced EMI, with a specified maximum data rate in the low-hundreds-of-kbps range per its datasheet. The ADM4855AR-REEL7 is a higher-speed 3.3 V transceiver supporting data rates up to several Mbps. The exact rated data rate for each device should be confirmed from the manufacturer datasheet for the specific grade.
How do the receiver input thresholds and bus compatibility compare?
Both devices are RS-485/RS-422 compliant transceivers with differential bus interfaces, but their receiver input thresholds and common-mode ranges are specified for their respective supply voltages. The ADM485AR is characterized at 5 V, while the ADM4855AR-REEL7 is characterized at 3.3 V. Mixing the two on the same bus requires checking that the differential output swing and receiver thresholds remain within the RS-485 standard limits for all nodes.
What does the -REEL7 suffix indicate on the ADM4855AR-REEL7?
The -REEL7 suffix denotes tape-and-reel packaging, typically 7-inch reels, used for automated assembly. It does not change the electrical characteristics of the device; the ADM4855AR-REEL7 is the same silicon as the ADM4855AR, supplied in reel form for high-volume production.
Which part should be selected for a 3.3 V system versus a 5 V system?
For a 3.3 V rail, the ADM4855AR-REEL7 is the appropriate choice because it is specified for 3.3 V operation. For a 5 V rail, the ADM485AR is the appropriate choice. Selecting the wrong device for the available supply will violate the datasheet operating conditions and may result in unreliable or out-of-specification operation.
Are both devices suitable for half-duplex RS-485 networks?
Yes, both the ADM485AR and ADM4855AR-REEL7 are half-duplex RS-485 transceivers with separate driver enable (DE) and receiver enable (RE) pins, allowing them to be used on two-wire differential buses. The choice between them depends primarily on the available supply voltage, required data rate, and pinout compatibility with the target design.