Part A
ADM4851ARZ
ADI公司
- Lifecycle
- Active
- Stock
- 4442 件
- Package
- SOIC-8
- Series
- 介面-驅動器、接收器、收發器
Replacement verdict
Compatible functional replacement candidate
The ADM485JRZ and ADM4851ARZ are both half-duplex RS-485/RS-422 transceivers in 8-lead SOIC packages with matched supply voltage and temperature ranges, making them strong functional replacement candidates. However, the ADM4851ARZ offers extended ESD protection and a higher maximum data rate, so designers should validate slew-rate, ESD, and bus-loading requirements against the target application before substituting.
Package Type
High match
Supply Voltage Range
High match
Maximum Data Rate
Validation required
ESD Protection Level
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADM485JRZ | ADM4851ARZ | Why it matters |
|---|---|---|---|
| Data Rate | 5 Mbps | 500 kbps | Maximum signaling speed; the two parts are not drop-in speed equivalents, so a design needing 5 Mbps cannot substitute the slower part. |
| Duplex Mode | Half-duplex | Half-duplex | Determines whether the transceiver can transmit and receive simultaneously; both are half-duplex, so bus topology compatibility is preserved. |
| Number of Drivers / Receivers | 1 / 1 | 1 / 1 | Defines the transceiver channel count; identical 1:1 configuration supports the same point-to-point or multidrop bus arrangement. |
| Receiver Input Impedance (Unit Loads) | 1 unit load (12 kΩ) | 1/8 unit load (96 kΩ) | Lower unit load allows more nodes on the bus; the 1/8-load part supports up to 256 nodes versus 32 for the standard-load part. |
| Fail-Safe Receiver | Not specified / standard | True fail-safe (open/short) | Fail-safe receivers guarantee a defined logic output on open or terminated-but-idle buses, preventing indeterminate states in the slower part's design. |
| Supply Voltage | 5 V | 5 V | Operating rail must match the system supply; both are 5 V single-supply devices, so power architecture is compatible. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Industrial temperature rating ensures reliable operation across the same environmental envelope for both parts. |
| Package / Mounting | 8-SOIC (surface mount) | 8-SOIC (surface mount) | Footprint and assembly compatibility; identical SOIC-8 packages allow board-level interchange without layout changes. |
| ESD Protection (Bus Pins) | ±15 kV (HBM, typical spec) | ±15 kV (HBM, typical spec) | Bus-pin ESD robustness affects field reliability; comparable ratings mean similar protection against transient events. |
Need help validating a replacement?
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADM4851ARZ | ADM485JRZ |
|---|---|---|
| Part Status | Active | Active |
| Type | Transceiver | Transceiver |
| Protocol | RS422, RS485 | RS422, RS485 |
| Number of Drivers/Receivers | 1/1 | 1/1 |
| Duplex | Half | Half |
| Receiver Hysteresis | 20 mV | 70 mV |
| Data Rate | 500kbps | 5Mbps |
| Voltage - Supply | 4.75V ~ 5.25V | 4.75V ~ 5.25V |
| Operating Temperature | -40°C ~ 85°C | 0°C ~ 70°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
Are the ADM485JRZ and ADM4851ARZ interchangeable in an existing RS-485 design?
No, they are not drop-in interchangeable. The ADM485JRZ is a standard 5 V RS-485 transceiver in an 8-lead SOIC package, while the ADM4851ARZ is a 3.3 V RS-485 transceiver in an 8-lead SOIC package with a different pinout and supply voltage requirement. The supply voltage, pin functions, and logic-level thresholds differ, so a direct substitution without design validation is not recommended.
What are the supply voltage requirements for the ADM485JRZ and ADM4851ARZ?
The ADM485JRZ operates from a single 5 V supply (typically 4.75 V to 5.25 V). The ADM4851ARZ operates from a single 3.3 V supply (typically 3.0 V to 3.6 V). The supply voltage difference is a primary reason the two devices are not directly interchangeable.
Do the ADM485JRZ and ADM4851ARZ have the same pinout?
No. Both are offered in 8-lead SOIC packages, but the pin assignments differ. The ADM485JRZ follows the standard 8-lead RS-485 pinout (RO, RE, DE, DI, GND, A, B, VCC), while the ADM4851ARZ has a different pin configuration. PCB layout and pin function verification against the respective datasheets are required before considering any replacement.
What data rates do the ADM485JRZ and ADM4851ARZ support?
The ADM485JRZ is specified for data rates up to 5 Mbps. The ADM4851ARZ is specified for data rates up to 500 kbps. The ADM485JRZ therefore supports higher data rates, which is a key selection criterion when comparing the two devices.
How do the logic-level compatibility requirements differ between the two devices?
The ADM485JRZ, operating from 5 V, has logic input thresholds compatible with 5 V logic families. The ADM4851ARZ, operating from 3.3 V, has logic thresholds designed for 3.3 V logic and is typically compatible with 3.3 V microcontrollers and FPGAs. Mixing a 5 V transceiver with 3.3 V logic, or vice versa, requires level-shifting or verification of input thresholds against the datasheet.
Are the ADM485JRZ and ADM4851ARZ both specified for the same operating temperature range?
Both devices are offered in industrial temperature range versions. The ADM485JRZ is specified over the -40°C to +85°C industrial temperature range. The ADM4851ARZ is also specified over the -40°C to +85°C industrial temperature range. Temperature range alone does not make them interchangeable; supply voltage, pinout, and data rate differences must also be considered.
Which device should be selected for a 3.3 V RS-485 bus design?
The ADM4851ARZ is the appropriate choice for a 3.3 V RS-485 bus design because it is specified to operate from a 3.3 V supply and its logic levels are compatible with 3.3 V controllers. The ADM485JRZ requires a 5 V supply and is not suitable for a 3.3 V-only rail without additional regulation or level shifting.
Do both devices provide the same ESD protection level?
ESD protection ratings should be verified against the respective manufacturer datasheets, as the two devices are from different product families and may have different specified ESD withstand levels on the bus pins. Designers should confirm the ESD specification for the selected device rather than assuming equivalence between the ADM485JRZ and ADM4851ARZ.