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The MLT-7525-16R 7.5*7.5*2.5mm SMD Magnetic Passive Buzzer represents a step up in the MLT SMD buzzer portfolio, addressing applications where the compact 5 mm series proves acoustically or electrically insufficient. With a 7.5 × 7.5 mm footprint and 2.5 mm height, this 16Ω 3.6V SMD electromagnetic passive buzzer occupies 2.25× the PCB area of its 5 mm counterparts while delivering measurably higher sound pressure and broader voltage compatibility.
The most significant departure from the 5 mm series lies in its electrical and acoustic tuning. The rated voltage increases to 3.6 V with an operating span of 2.5–4.5 V, directly accommodating single-cell Li-ion batteries (3.0–4.2 V nominal) and 5 V logic systems without voltage regulation. The resonant frequency drops to 2700 ± 300 Hz — a range where human hearing remains sensitive while ambient mechanical and electrical noise typically diminishes, improving signal-to-noise ratio in industrial environments.
The 16 ± 3 Ω coil resistance represents a deliberate design choice for higher-voltage operation. At 3.6 V, the current draw remains ≤ 100 mA while the increased coil turns and larger diaphragm area generate ≥ 85 dB output. This impedance level suits applications where driver circuits operate from 5 V rails or where reduced current consumption is prioritized over minimal component count.
Manufactured by MEIDI, the MLT-7525-16R incorporates a wider temperature envelope than the 5 mm series — operating from -30 °C to +70 °C and storing from -40 °C to +85 °C. This extended range supports deployment in outdoor equipment, unheated enclosures, and automotive interior applications where thermal excursions exceed standard consumer-grade limits. Contact us to request a quotation or submit an RFQ for volume pricing.
Expanded 7.5 × 7.5 mm footprint with 2.5 mm profile for superior acoustic output in compact SMD form
Higher rated voltage 3.6 V with 2.5–4.5 V operating range — compatible with 3.7 V Li-ion and 5 V logic systems
Lower 2700 ± 300 Hz resonant frequency — penetrates ambient noise more effectively than 4 kHz alternatives
Elevated ≥ 85 dB sound pressure at 10 cm for demanding industrial and safety applications
16 ± 3 Ω coil resistance optimized for higher-voltage drive circuits with reduced current demand
Extended temperature range: -30 °C to +70 °C operating, -40 °C to +85 °C storage
Expanded acoustic diaphragm area — 7.5 mm square housing accommodates a larger vibrating membrane than 5 mm variants, increasing sound pressure generation efficiency at lower frequencies
2.7 kHz low-frequency resonance — targets the 2–3 kHz band where human auditory sensitivity intersects with reduced ambient noise, improving perceptibility in industrial and outdoor settings
3.6 V rated voltage with 2.5–4.5 V range — native compatibility with Li-ion cells, 5 V logic, and automotive 12 V systems through simple resistive or transistor drive
16 ± 3 Ω impedance for higher-voltage efficiency — reduced current draw at elevated voltages compared to 12 Ω alternatives, easing thermal management in driver circuits
Extended -30 °C to +70 °C operating range — outperforms standard -20 °C lower limits, supporting cold-start and sub-zero deployment scenarios
Black LCP housing with 2.5 mm low profile — maintains vertical clearance discipline while maximizing internal acoustic cavity volume
| Parameter | Value |
| Product Type | Electromagnetic SMD Passive Buzzer |
| Rated Voltage | 3.6 V (o-p) |
| Operating Voltage | 2.5 – 4.5 V (o-p) |
| Sound Output at 10 cm | ≥ 85 dB |
| Operating Current | ≤ 100 mA |
| Resonant Frequency | 2700 ± 300 Hz |
| Coil Resistance | 16 ± 3 Ω |
| Operating Temperature | -30 °C ~ +70 °C |
| Storage Temperature | -40 °C ~ +85 °C |
| Dimensions (L × W × H) | 7.5 × 7.5 × 2.5 mm |
| Weight | 0.5 g |
| Housing Material | Black LCP |
| Soldering Method (Recommended) | Reflow: 255 ± 5 °C, 3 s; Preheat 180 °C, 40–70 s |
The 7.5*7.5*2.5mm SMD Magnetic Passive Buzzer occupies a distinct position in the SMD buzzer landscape: it bridges the gap between compact 5 mm devices and bulky through-hole magnetic buzzers. For engineers constrained to surface-mount assembly but requiring acoustic output beyond what 5 mm packages can deliver, this 16Ω 3.6V SMD electromagnetic passive buzzer provides a viable intermediate solution.
The frequency selection warrants particular attention. At 2700 Hz, the MLT-7525-16R operates below the 4 kHz cluster where most compact buzzers concentrate. This matters in two contexts: first, lower frequencies propagate with less atmospheric attenuation over short distances; second, industrial environments typically exhibit lower noise spectral density in the 2–3 kHz band compared to the 4 kHz region where cooling fans, switching power supplies, and digital electronics generate substantial interference.
The 16 Ω impedance introduces a different drive circuit paradigm than the 12 Ω series. While direct GPIO drive from 3.3 V microcontrollers is less practical (current would exceed typical 25 mA pin limits), the higher impedance pairs naturally with 5 V logic, dedicated driver ICs, or simple transistor stages operating from Li-ion or regulated supplies. The resulting system often achieves better electromagnetic compatibility due to lower current transients.
The 0.5 g mass — five times the 0.1 g of 5 mm variants — contributes to mechanical robustness. The increased inertia resists vibration-induced microphonic effects and provides more stable acoustic output under mechanical shock conditions. Request a sample to evaluate low-frequency penetration in your target environment.
Industrial machinery alarm systems — emergency stop, fault, and overload alerts in CNC machines, presses, and material handling equipment where ambient noise exceeds 70 dB
Outdoor telecommunications infrastructure — cabinet intrusion, power failure, and thermal excursion warnings in base stations, repeaters, and network nodes
Commercial vehicle interior systems — reverse alarm, seatbelt reminder, and cargo door alerts in vans, trucks, and construction equipment
Agricultural and construction machinery — operational status and safety boundary warnings in tractors, excavators, and harvesters exposed to vibration and dust
Uninterruptible power supplies (UPS) — battery mode, overload, and maintenance alerts in data center and medical-grade backup power systems
Cold-chain logistics equipment — temperature breach and door-open alarms in refrigerated transport containers and walk-in freezers
MEIDI applies consistent reliability protocols across all MLT series production, with the MLT-7525-16R subjected to the same comprehensive stress verification:
•Climatic endurance validation — 48-hour high-temperature storage at +80 ± 2 °C, 48-hour low-temperature storage at -30 ± 2 °C, and 5-cycle thermal shock (-30 °C ↔ +80 °C, 30-minute dwell)
•Mechanical stress testing — sinusoidal vibration (10–55 Hz, 1.0 mm amplitude, XYZ axes, 0.5 hours cumulative) and 75 cm free-fall drop onto 10 mm hardwood (3 impacts)
•Humidity resistance verification — 48-hour conditioning at 50 ± 5 °C / 90–95% RH followed by 2-hour ambient recovery and full electrical characterization
•Soldering integrity confirmation — solder heat resistance at 250 ± 5 °C for 10 ± 0.5 seconds (2.0 mm body-to-solder clearance), plus full reflow profile compliance
Sample batch test data (10 units, 3.6 V standard drive, 10 cm) confirms: sound pressure 87.3--89.5 dB, current 71.0--72.7 mA, frequency 2705--2735 Hz, impedance 16.0--16.7 Ω --- all within specification tolerances.
1. Why does the MLT-7525-16R use 16 Ω rather than the 12 Ω common in smaller SMD buzzers?
The 16 Ω coil is optimized for the 3.6 V rated voltage and 2.5–4.5 V operating range. At these voltages, a 12 Ω coil would draw excessive current (up to 300 mA at 3.6 V), exceeding standard driver capabilities and generating unwanted heat. The 16 Ω impedance maintains current ≤ 100 mA while allowing sufficient coil turns to drive the larger diaphragm at 2.7 kHz. This represents a system-level optimization rather than a simple resistance choice.
2. Can the MLT-7525-16R be driven directly from a 3.3 V microcontroller GPIO?
Not recommended. At 3.3 V, a 16 Ω coil would draw approximately 206 mA — well beyond the 20–25 mA typical limit of standard MCU pins and risking permanent damage. A simple NPN transistor or MOSFET driver stage is required. For 5 V systems, a 180 Ω base resistor with a general-purpose transistor (HF ≥ 200) provides adequate drive, similar to the standard test circuit used for characterization.
3. How does the 2.7 kHz frequency compare to 4 kHz buzzers in practical applications?
The 2.7 kHz resonant frequency offers superior penetration in noisy environments and reduced directional beaming compared to 4 kHz. Human hearing sensitivity is comparable between these frequencies (both fall within the 2–5 kHz most-sensitive band). The primary trade-off is physical size: achieving 2.7 kHz resonance in a compact package requires a larger diaphragm, which the 7.5 mm housing accommodates. For applications where 4 kHz buzzers are inaudible due to environmental noise, the MLT-7525-16R provides a direct upgrade path.
4. What is the significance of the -40 °C storage temperature rating?
The extended storage range to -40 °C supports cold-chain logistics, high-altitude equipment, and winter-stored machinery where standard -30 °C limits may be exceeded during transport or idle periods. The operating limit remains -30 °C, meaning the device should not be actively driven below this temperature, but can survive storage excursions to -40 °C without degradation. This distinction is critical for aerospace, arctic, and cryogenic-adjacent applications.
5. Is the MLT-7525-16R suitable as a drop-in replacement for through-hole magnetic buzzers in existing designs?
Yes, with PCB layout revision. The 7.5 mm SMD footprint occupies comparable board area to many 9 mm and 12 mm through-hole buzzers while eliminating the need for drilled holes and manual insertion. The ≥ 85 dB sound pressure guarantee provides design margin for industrial alert applications. The primary design consideration is the drive circuit: through-hole buzzers often operate at 12 V with internal oscillators, while the MLT-7525-16R requires external 2.7 kHz excitation at 3.6 V. A simple oscillator or MCU PWM output replaces the self-oscillating drive previously provided by the active buzzer.
Contact MEIDI for competitive quotations, engineering samples, and OEM/ODM customization. Our applications team can assist with driver circuit design for 5 V and Li-ion systems, acoustic enclosure modeling, and reflow profile optimization for your production line.
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