ROHM BH1750FVI PCB footprint, checks, and sourcing guide

The ROHM BH1750FVI is a digital ambient-light sensor from ROHM Semiconductor. Its package or board interface is 6-pin 3.0 × 1.6 mm WSOF, and its relevant electrical envelope is 2.4–3.6 V. It communicates or connects through I²C at 0x23 or 0x5C via ADDR. Those fields belong together: substituting a familiar family name while changing package, voltage, sensing port, mount style, current class, or interface behavior can leave a PCB that passes ordinary net checks and still cannot be assembled or function safely.

BH1750FVI is a straightforward lux sensor with two selectable addresses and built-in spectral response, but uses a fine WSOF optical package.

Common uses include simple lux measurement and backlight and lighting controls. Start with the manufacturer drawing and recommended application, then record the exact ordering suffix alongside the KiCad symbol and footprint. This makes the library evidence reviewable when the part is re-sourced months later.

• Use the exact optical-package footprint and preserve the emitter/receiver apertures. The courtyard must include the line of sight, cover-glass gap, and any manufacturer-specified optical isolation wall.
• Keep solder mask, silkscreen, adhesive, flux, and conformal coating out of the optical opening. Dark solder mask can still reflect infrared; mechanical baffling often matters more than color.

Give the optical window a clear field, strap ADDR deliberately, and keep the sensor away from local LEDs and display leakage.

• Place the sensor against a controlled enclosure window with the recommended air gap. Separate emitter light from the receiver using a gasket or baffle and prevent status LEDs from leaking into the optical path.
• Decouple supply and LED-current rails, observe I/O voltage, and route interrupts and buses away from fast LED-current loops. Follow cover-glass crosstalk calibration where the device requires it.

Put the support components where their current, thermal, optical, RF, or measurement loops are actually short—not merely where ratsnest lines look tidy. Confirm pin one from the package view used in the datasheet, distinguish top view from mating face or bottom view, and check mask, paste, drill, courtyard, enclosure, and rework access independently. A correct copper pad pattern can still be a bad production footprint when the sensing opening, connector latch, exposed pad, thermal path, or cable volume is wrong.

MakeIRL’s release gate should not stop at “the symbol has the right number of pins.” For this part, a useful gate review combines ERC/DRC with the following package- and function-specific evidence:

1. Check optical orientation, window and baffle geometry, aperture keepout, supply rails, decoupling, I²C address, interrupts, and emitter-current components.
2. Check for enclosure clipping, internal reflections, solder/adhesive contamination, and electrical crosstalk from LEDs, displays, or switching regulators.
3. Check exact package and suffix; many optical sensors have the same family name but different field of view, filter, or recommended window stack.
4. For ROHM BH1750FVI, check WSOF land pattern and aperture, ADDR strap, DVI/decoupling capacitor, window attenuation, I²C pull-ups, and measurement mode.

Then run ERC and DRC, refill zones, and inspect the fabrication and assembly outputs. Cross-probe the exact pads named by any finding, compare the BOM MPN with the footprint and electrical limits above, and verify that a real cable, enclosure, antenna, sensor stimulus, load, or thermal path can be tested on the assembled unit. An exclusion is evidence that someone dismissed a marker; it is not evidence that the underlying condition was resolved.

The most expensive errors are usually plausible: a footprint from a sibling package, a breakout-board voltage copied to the bare IC, a headline current used without thermal analysis, or a connector family selected by pitch alone. For ROHM BH1750FVI, review these failure modes explicitly:

• Leaving ADDR midway or floating can produce an unstable address that appears as intermittent I²C wiring.
• Testing an exposed development board successfully, then adding a glossy cover window that saturates the receiver with internal reflection.
• Putting silkscreen or a pick-and-place vacuum target over the optical aperture.

Sourcing note. Use genuine ROHM BH1750FVI; many low-cost modules use clones or compatible parts with different calibration. The approved vendor list should preserve manufacturer, full suffix, package, voltage/range/accuracy grade, lifecycle, and mating or external components. An alternate is real only after its datasheet, land pattern, electrical behavior, firmware assumptions, and assembly process have all been compared—not because a distributor search places it in the same parametric row.