When buying an I2C isolator, “two channels” and “SOIC-8” do not establish functional equivalence. For ADUM1251ARZ-RL7, first ask your engineer whether the device across the isolation barrier needs to pull SCL low to make the controller wait. That answer can determine suitability before price becomes relevant.

What is ADUM1251ARZ-RL7?

This part belongs to the Analog Devices ADuM1251 I2C signal-isolator family. The ADuM1250/ADuM1251 Rev. L datasheet specifies bidirectional SDA but unidirectional SCL for ADuM1251: SCL1 is the Side 1 input and SCL2 the Side 2 output. Each side operates from 3.0–5.5V, with operation up to 1000kHz subject to loading and timing requirements. This A-grade part uses an 8-lead SOIC package and is rated from −40°C to +105°C; do not apply the +125°C rating of other grades.

ADuM1251 versus ADuM1250: can the clock travel back?

ADuM1250 provides bidirectional SDA and SCL; ADuM1251 provides bidirectional SDA only. Consequently, if a target on Side 2 pulls SCL low for clock stretching, ADuM1251 cannot propagate that action backward to a controller on Side 1 through its one-way clock path. Similar names and packages do not establish an unverified drop-in replacement.

A practical selection check is to mark the controller, target and isolator sides on the schematic. Review the target datasheet and the operating modes actually used by firmware. If the target needs clock stretching, or multiple controllers may drive the clock, reassess the isolation topology and the need for a bidirectional clock path.

Check the entire bus, not just its headline speed

Analog Devices AN-913 explains the relationship between the I2C open-drain bus and pull-up resistors. Both sides require suitable pull-ups. Give engineering the intended bus speed, voltages on each side, connector and cable arrangement, and number of connected devices. A maximum speed specification is not a guarantee for arbitrary wiring.

During sample evaluation, record rise time, low levels and acknowledgements under the intended load, supply and temperature conditions. Side 1 has modified low-level thresholds, so the two sides should not be treated as electrically interchangeable. Check pull-up selection and capacitance limits against the current datasheet.

Signal isolation does not supply isolated power

This device transfers isolated signals; it does not generate an isolated supply for the other side. Review the power arrangement and local reference ground on each side before purchasing the BOM. If the design requires an isolated DC/DC module, that is a separate sourcing item.

The datasheet's 2500Vrms UL 1577 specification is a one-minute withstand test rating, not a claim of continuous operation at 2500Vrms. Actual insulation design also depends on working voltage, PCB spacing and applicable standards, which the responsible design engineer must assess.

Five details to include in your RFQ

  • Full ordering code: Specify ADUM1251ARZ-RL7 without dropping suffixes. Ask the supplier to confirm the supplied packaging, units per reel and whether the shipment is a partial reel.

  • Project stage: Identify engineering samples, pilot production or volume production. State quantity and requested delivery date, and obtain confirmation of achievable terms.

  • Lot requirements: Explain whether mixed lots are acceptable, any date-code restrictions, and which labels and traceability records must be retained.

  • Acceptance criteria: Agree on appearance, packaging, quantity and required functional checks before ordering. A label photograph is not proof of authenticity or available inventory.

  • Substitution approval: Route any proposed ADuM1250 or other isolator substitution through engineering review instead of deciding on price alone.

Common purchasing questions

Can it be used with every I2C sensor? An I2C interface alone is insufficient. Confirm clock stretching, logic levels, timing and bus loading, then validate samples.

Does the label quantity equal available stock? No. A label may describe the original package quantity. Available quantity, lot and delivery terms need written confirmation; the label alone also does not establish authenticity.

Where can I view the exact product and request a quote? Visit the WOMAiELEC ADUM1251ARZ-RL7 product page and provide the complete part number, quantity, packaging and lot requirements. If a catalog field conflicts with manufacturer documentation, use current manufacturer documentation for technical selection. Pricing, availability and lead time remain subject to supplier confirmation.

Manufacturer references

This guide supports purchasing discussions and selection checks. Final circuit and substitution decisions require validation in the actual design.