Part A
ADM4851ARZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4442 PCS
- Package
- SOIC-8
- Series
- Interface - Drivers, Receivers, Transceivers
Replacement verdict
Compatible functional replacement candidate
The ADM4851ARZ and ADM4852AR are both half-duplex RS-485/RS-422 transceivers in an 8-lead SOIC package with identical pinout and supply voltage requirements, making them strong functional replacement candidates. The primary distinction lies in their data rate and slew-rate characteristics, so the ADM4852AR can serve as a drop-in substitute for the ADM4851ARZ provided the system's data rate and EMI profile are validated against the target application.
Package Type
High match
Pin Configuration
High match
Supply Voltage
High match
Data Rate
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 | ADM4851ARZ | ADM4852AR | Why it matters |
|---|---|---|---|
| Data Rate | 500 kbps | 2.5 Mbps | Maximum signaling speed; the faster part supports higher-throughput buses while the slower part is limited to lower-speed networks. |
| Duplex Mode | Half-duplex | Half-duplex | Determines whether the transceiver can transmit and receive simultaneously; both are half-duplex, so they are functionally aligned here. |
| Number of Drivers/Receivers | 1/1 | 1/1 | Defines the channel count per package; identical configuration means either can serve a single bidirectional bus node. |
| Supply Voltage | 5 V | 5 V | Operating rail must match the system supply; both require a 5 V nominal supply for proper RS-485 levels. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Defines the environmental envelope; matching industrial ranges allow interchangeability in most applications. |
| Package / Mounting | 8-SOIC (surface mount) | 8-SOIC (surface mount) | Footprint and assembly compatibility; identical SOIC packages permit drop-in board replacement. |
| Fail-Safe Receiver | Yes | Yes | Ensures a defined logic output when the bus is idle or open, preventing spurious data in multi-node networks. |
| ESD Protection (Bus Pins) | ±15 kV (HBM) | ±15 kV (HBM) | Robustness against electrostatic discharge on the bus; equal ratings mean comparable field reliability. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADM4851ARZ | ADM4852AR |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Type | Transceiver | Transceiver |
| Protocol | RS422, RS485 | RS422, RS485 |
| Number of Drivers/Receivers | 1/1 | 1/1 |
| Voltage - Supply | 4.75V ~ 5.25V | 4.75V ~ 5.25V |
| Mounting Type | Surface Mount | Surface Mount |
| Duplex | Half | - |
| Receiver Hysteresis | 20 mV | - |
| Data Rate | 500kbps | - |
| Operating Temperature | -40°C ~ 85°C | - |
Frequently asked questions
What are the key differences between the ADM4851ARZ and ADM4852AR?
Both are half-duplex RS-485/RS-422 transceivers in 8-lead SOIC packages from Analog Devices. The ADM4851ARZ is specified for data rates up to 500 kbps with a slew-rate-limited driver, while the ADM4852AR supports data rates up to 2.5 Mbps. The ADM4851ARZ is typically characterized for lower EMI due to its limited slew rate, whereas the ADM4852AR is intended for higher-speed communication. Both operate from a single 5 V supply and feature fail-safe receiver inputs.
Are the ADM4851ARZ and ADM4852AR pin-compatible?
Yes. Both devices are offered in the same 8-lead SOIC (R-8) package with an identical pinout: RO, RE, DE, DI, GND, A, B, and VCC. This allows them to share the same PCB land pattern, though the higher data rate of the ADM4852AR may require attention to layout and termination for signal integrity.
What supply voltage do the ADM4851ARZ and ADM4852AR require?
Both devices operate from a single 5 V ±5% supply (4.75 V to 5.25 V). They are not 3.3 V parts; designs requiring 3.3 V operation should use a different transceiver family.
What data rates do the ADM4851ARZ and ADM4852AR support?
The ADM4851ARZ is specified for data rates up to 500 kbps and uses a slew-rate-limited driver to reduce EMI and reflections. The ADM4852AR is specified for data rates up to 2.5 Mbps. The maximum cable length and termination should be selected according to the chosen data rate.
Do the ADM4851ARZ and ADM4852AR include fail-safe receiver inputs?
Yes. Both devices feature fail-safe receiver inputs, which ensure a known logic-high receiver output when the bus is open, shorted, or idle (no driver active). This prevents indeterminate output states on an undriven bus.
How many nodes can be connected on a bus using the ADM4851ARZ or ADM4852AR?
Both devices present a 1/4 unit load to the RS-485 bus, allowing up to 128 transceivers to be connected to a single bus segment, consistent with the standard RS-485 unit-load budget. Actual node count should also account for termination and bias resistors.
What is the operating temperature range for the ADM4851ARZ and ADM4852AR?
Both devices are specified over the industrial temperature range of −40 °C to +85 °C, making them suitable for industrial networking, building automation, and similar environments.
Can the ADM4851ARZ be replaced by the ADM4852AR in an existing design?
Because they are pin-compatible and share the same supply and unit-load characteristics, the ADM4852AR can generally replace the ADM4851ARZ where higher data rates are needed. However, the faster edge rates of the ADM4852AR increase EMI and require proper termination and layout review; the substitution should be validated against the system's signal-integrity and EMC requirements.