The MAX3158 is a high CMRR RS-485/RS-422 data communications interface providing ±60V isolation in a hybrid microcircuit. A single +5V supply on the logic side powers both sides of the interface, with external 100V capacitors transferring power from the logic side to the isolated side. Each MAX3158 contains one transmitter and one receiver and is guaranteed to operate at data rates up to 250kbps. Drivers are short-circuit current limited and protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high receiver output if the inputs are open, shorted, or connected to a terminated transmission line with all drivers disabled. The MAX3158 typically draws 25mA of supply current when unloaded or when fully loaded with the driver disabled. Supply current drops to 25µA when the device is placed in shutdown mode. The device is pin selectable between half- and full-duplex mode and also features an independently programmable receiver and transmitter output phase through separate pins. The MAX3158 is a low-cost replacement for opto-isolated transceivers. For fully isolated RS-485/RS-422 transceivers, refer to the MAX1480 family data sheet.
The MAX3158 is a high common‑mode‑rejection RS‑485/RS‑422 transceiver that provides ±60 V isolation in a hybrid microcircuit. It operates from a single +5 V supply, with external 100 V capacitors transferring power to the isolated side. The device includes a driver and a receiver, supports up to 250 kbps data rates, and offers fail‑safe operation that guarantees a logic‑high output when inputs are open or shorted.
Key functional features include pin‑selectable half‑ or full‑duplex mode, independent programmable phase control for driver and receiver, short‑circuit current limiting, thermal shutdown protection, and a low‑power shutdown mode that reduces supply current to 25 µA. The transceiver is offered in 28‑pin SSOP and PDIP packages and is positioned as a low‑cost alternative to opto‑isolated transceivers.
| Supply Voltage (VCC) | +5 V ±5 % |
|---|---|
| Isolation Voltage | ±60 V |
| Maximum Data Rate | 250 kbps |
| No‑Load Supply Current | 25 mA |
| Shutdown Supply Current | 25 µA |
| Operating Temperature Range (SSOP) | 0 °C to +70 °C |
| Receiver Threshold | -50 mV to -200 mV |
The MAX3158 can operate at data rates up to 250 kbps.
In shutdown mode the device draws only about 25 µA of supply current.
The transceiver requires a single +5 V supply (±5 %).
It provides ±60 V isolation between the logic side and the isolated side.