Product Overview
Uncompensated Silicon Pressure Sensor Element, Unused NOS with Legible Cap Markings
Condition
Unused, New Old Stock. The photographed piece shows a bright metal cap marked MPX2101D on the first line and M 8645 on the second, both fully legible, with a small port opening at the center of the cap. The molded black body behind it carries a second center opening and a small molded boss. All four leads are gold colored, straight, full length, and free of solder, tinning, cut marks, or bends. No corrosion, chipping, or handling damage is visible on either face.
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Product Overview
The MPX2101D is a monolithic silicon piezoresistive pressure sensing element from Motorola's MPX2100/2101 series, supplied here as a raw, uncompensated sensor rather than a finished transducer. Applied pressure unbalances an internal Wheatstone bridge and produces a low-level millivolt output that is ratiometric to the supply voltage, so the designer sets gain, offset, and temperature compensation in their own analog front end. Nominal span is 0-100 kPa. The element arrives in the round chip-carrier style package the series is known for: a metal cap with a center port over a molded body, four straight leads in a single row, and the part number stamped on the cap face where you can still read it years after the reel and the datasheet went missing.
Key Features
- Device: Motorola MPX2101D uncompensated silicon piezoresistive pressure sensor element
- Output: low-level millivolt signal proportional to applied pressure
- Nominal pressure span: 0-100 kPa
- Sensing configuration: Wheatstone bridge
- Supply behavior: output ratiometric to supply voltage
- Signal conditioning: none on board, external amplification and compensation required
- Package: chip-carrier style element, metal cap over molded body, four straight leads
- Cap marking (from the photos): MPX2101D over M 8645
Applications
- Instrumentation designer building a custom pressure channel around their own instrumentation amplifier and offset trim
- HVAC or airflow controls engineer prototyping a duct pressure board where the analog front end is already chosen
- Bench technician assembling a low-pressure test rig and calibrating the whole chain against a known reference
- Maintainer matching an original MPX2100 series element in older equipment that expects a raw bridge input
- Instructor demonstrating bridge sensing, gain, and temperature compensation on real silicon instead of a simulation
Frequently Asked Questions
Does this element include amplification or calibration?
No. It gives you a raw bridge output only. Plan on an external instrumentation amplifier plus your own offset and temperature compensation, which is the whole reason to buy an uncompensated element.
Can the output drive an ADC input directly?
Not usefully. The signal is millivolt level, so it is normally amplified first. Because the bridge output is ratiometric to the supply, feeding the ADC from the same reference keeps the conversion stable.
Which pressure reference and port arrangement does this element use?
The listing describes it as an absolute element, and the earlier text notes that differential or gauge measurement is possible depending on port configuration. The photos show a port opening at the center of the metal cap and a second opening in the molded back. Not confirmed here: check the D suffix against the MPX2100 series datasheet before you commit it to a board.
What does the second line on the cap mean?
The cap reads MPX2101D over M 8645. The first line is the part number. The second is a factory code, and we have not confirmed how it decodes, so treat it as traceability rather than a specification.
Why buy this photographed element instead of a mixed surplus sensor lot?
Because you know exactly what lands on your bench. This is a stock of four, shot front and back with the cap marking readable, leads uncut and unsoldered, sold one or two at a time for the prototype in front of you. A pallet lot gets you unmarked sensors, an afternoon of sorting, and a redesign when the port arrangement turns out wrong. Shipping is $8 flat rate and free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
An uncompensated element is a deliberately unfinished instrument: the silicon and the bridge came from the factory, and the gain, the offset, and the temperature curve were always meant to be somebody else's work. Wire it to your own amplifier and that last part of the design is yours to write.
