DÜSSELDORF — Toshiba Electronics Europe has widened its DCL34xx0B standard digital-isolator family with four quad-channel parts aimed at industrial automation, not at the automotive DCM line. The pitch is practical: typical current of 0.2 mA per channel, data rates to 25 Mbps, and a −40 °C to +125 °C operating range in an SSOP16 package.

That combination is meant for the boards that actually sit between logic and a noisy plant—programmable-logic-controller I/O, sensor and actuator interfaces, motor drives, inverters, and switching power supplies. Isolation here is not a catalog checkbox. Faster silicon on the same card raises common-mode transients; a missed isolation barrier is how a ground bounce on a drive becomes a false trip on a PLC input.

Toshiba’s DCL34xx0B family: magnetic-coupling quad-channel isolators in SSOP16 for industrial I/O and control boards.

What the four new part numbers actually change

The new devices fill channel maps the series did not yet cover. DCL340L0B and DCL340H0B are four-forward, zero-reverse (4:0) parts for unidirectional digital runs. DCL342L0B and DCL342H0B are two-forward, two-reverse (2:2) parts for bidirectional links. They sit beside the already shipping DCL341L0B / DCL341H0B, which use a 3:1 map that fits SPI-style clocks and data.

The L/H suffix is default output logic—low or high—when the input is undefined at power-up or left floating. That is the sort of pin-level detail that decides whether a reset line glitches a drive enable during the first milliseconds after 24 V comes up.

Isolation numbers that matter on a DIN-rail card

All four parts are specified for a minimum isolation voltage of 3,000 Vrms (one minute) and a minimum common-mode transient immunity of 30 kV/μs. Supply range is 2.25 V to 5.5 V on both sides of the barrier, so the same isolator can sit between a 3.3 V MCU and a 5 V field-side translator without a second regulator just for the coupler.

Toshiba uses magnetic-coupling isolation—modulation and demodulation dice stacked with an isolation layer, signals crossing as a magnetic field—rather than an LED/photodiode pair. The company still sells photocouplers; the digital-isolator line is the answer when designers want lower idle current and a longer life story than an aging LED. Toshiba quotes 0.2 mA typical per channel from the 1 Mbps operating current (IDD1 + IDD2) divided by four channels at 3.3 V, 25 °C. At 25 Mbps the currents rise, as they must: on the 4:0 parts Toshiba lists about 6.7 mA primary and 5.4 mA secondary typical under its 25 Mbps test setup. Propagation delay is 52 ns maximum at 3.3 V.

Those figures will not impress a 150 Mbps isolator datasheet. They are meant for mid-speed industrial links—SPI, UART, GPIO banks on a PLC or inverter card—where 25 Mbps is enough and heat in a sealed cabinet is not.

Where the family sits

DCL34xx0B is Toshiba’s compact industrial isolator series. Higher-speed industrial parts remain in DCL54xx01A and DCL52xx00; automotive-qualified parts are DCM34xx01 and DCM32xx00. The August additions do not invent a new isolation physics. They give I/O designers 4:0 and 2:2 maps in the same SSOP16 (4.9 × 6.0 × 1.75 mm) that already holds the 3:1 SPI-friendly devices, so a board family can share a footprint while the schematic changes channel direction.

For control OEMs laying out isolated I/O on PLC and PAC systems, the useful question is not whether isolation is required—it is—but whether the channel map, default logic, and CMTI match the transients the adjacent drive or 24 V field already produces.