Part A
ADM1491EBRZ
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 2635 PCS
- Package
- SOIC-14
- Series
- Interface - Drivers, Receivers, Transceivers
Replacement verdict
Compatible functional replacement candidate
The ADM1491EBRZ is a functional replacement candidate for the ADM1485ARZ, sharing the same RS-485 transceiver function, SOIC-8 footprint, and 5 V supply rail, but it is not a pin-for-pin drop-in: the ADM1491EBRZ offers higher ESD protection and full-duplex capability versus the half-duplex ADM1485ARZ, so the system-level interface topology and bus wiring must be validated before substitution.
Function Type
High match
Package Type
High match
Duplex Mode
Validation required
ESD Protection Level
Validation required
Parts at a glance
Part B
ADM1485ARZ
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5260 PCS
- Package
- SOIC-8
- Series
- Interface - Drivers, Receivers, Transceivers
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADM1485ARZ | ADM1491EBRZ | Why it matters |
|---|---|---|---|
| Data Rate | 2.5 Mbps | 16 Mbps | Maximum signaling rate; the higher-speed part can replace the slower one in most designs, but not vice versa if the bus runs above 2.5 Mbps. |
| Duplex Mode | Half-duplex | Full-duplex | Determines whether transmit and receive can occur simultaneously and how many bus wires are required; full-duplex parts are not drop-in substitutes in half-duplex wiring. |
| Number of Drivers / Receivers | 1 / 1 | 1 / 1 | Confirms the transceiver channel count matches, which is essential for pin-function compatibility on the bus interface. |
| Supply Voltage | 5 V | 5 V | Both operate from a single 5 V rail, so power-supply architecture is compatible between the two parts. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical industrial temperature ratings mean either part suits the same environmental conditions. |
| Package / Mounting | 8-SOIC, surface mount | 8-SOIC, surface mount | Same package and footprint allow board-level interchangeability without layout changes. |
| Receiver Input Impedance (Unit Loads) | 1 unit load (12 kΩ) | 1 unit load (12 kΩ) | Determines how many nodes can share the RS-485 bus; matching unit-load ratings preserve maximum node count. |
| Fail-Safe Receiver | Yes (open-circuit fail-safe) | Yes (open-circuit fail-safe) | Guarantees a defined logic output when the bus is idle or disconnected, preventing indeterminate receiver states. |
| ESD Protection (Bus Pins) | ±15 kV (HBM, typical spec) | ±15 kV (HBM, typical spec) | Equivalent ESD robustness on the bus pins supports comparable field reliability and handling tolerance. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADM1491EBRZ | ADM1485ARZ |
|---|---|---|
| Part Status | Active | Active |
| Type | Transceiver | Transceiver |
| Protocol | RS422, RS485 | RS422, RS485 |
| Number of Drivers/Receivers | 1/1 | 1/1 |
| Duplex | Full | Half |
| Receiver Hysteresis | 30 mV | 70 mV |
| Data Rate | 16Mbps | 30Mbps |
| 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
What are the primary differences between the ADM1485ARZ and ADM1491EBRZ?
The ADM1485ARZ is a 5 V, low-power, high-speed RS-485/RS-422 transceiver specified for data rates up to 2.5 Mbps, supplied in an 8-lead SOIC package. The ADM1491EBRZ is a 5 V, ±15 kV ESD-protected, full-duplex RS-485/RS-422 transceiver with data rates up to 16 Mbps, supplied in an 8-lead SOIC package. Key differences include duplex configuration (half-duplex vs. full-duplex), maximum data rate, ESD protection level, and the ADM1491E's enhanced ESD robustness.
Are the ADM1485ARZ and ADM1491EBRZ pin-compatible?
No. The ADM1485ARZ is a half-duplex transceiver with a standard 8-lead pinout (RO, RE, DE, DI, GND, A, B, VCC). The ADM1491EBRZ is a full-duplex transceiver with a different 8-lead pinout that includes separate driver and receiver differential pairs (RO, RE, DE, DI, GND, A, B, Z, Y, VCC arrangement differs). Because the pin functions and signal assignments differ, they are not direct drop-in replacements and require PCB layout changes.
What is the maximum data rate of each device?
The ADM1485ARZ supports data rates up to 2.5 Mbps. The ADM1491EBRZ supports data rates up to 16 Mbps. The higher data rate of the ADM1491EBRZ makes it suitable for higher-speed RS-485/RS-422 communication links, while the ADM1485ARZ is intended for standard low-speed industrial networks.
What ESD protection levels do these transceivers offer?
The ADM1485ARZ provides standard ESD protection consistent with the ADM1485 family (typically ±8 kV contact discharge on the bus pins per the datasheet). The ADM1491EBRZ features enhanced ESD protection of ±15 kV on the RS-485/RS-422 bus pins, making it more robust in harsh industrial environments where electrostatic discharge is a concern.
Do both devices operate from a single 5 V supply?
Yes. Both the ADM1485ARZ and ADM1491EBRZ operate from a single 5 V ±10% supply (4.75 V to 5.25 V). Both are designed for 5 V RS-485/RS-422 systems and are not 3.3 V compatible without level shifting.
What is the difference in duplex configuration between the two parts?
The ADM1485ARZ is a half-duplex transceiver, meaning the driver and receiver share the same differential bus pair (A and B), requiring direction control via DE and RE pins. The ADM1491EBRZ is a full-duplex transceiver, providing separate driver outputs (Y and Z) and receiver inputs (A and B), allowing simultaneous transmit and receive operation over a four-wire bus.
Which device is better suited for a four-wire RS-422 system?
The ADM1491EBRZ is the appropriate choice for four-wire RS-422 systems because its full-duplex configuration provides independent driver outputs (Y, Z) and receiver inputs (A, B). The ADM1485ARZ, being half-duplex, is intended for two-wire RS-485 buses and cannot directly support simultaneous bidirectional communication on a four-wire link.
Are both devices available in the same package type?
Yes. Both the ADM1485ARZ and ADM1491EBRZ are offered in an 8-lead SOIC package (SOIC_N). However, despite the identical package outline, the pin functions differ between the half-duplex ADM1485ARZ and the full-duplex ADM1491EBRZ, so they are not interchangeable without layout redesign.