12*5.5mm Piezoelectric Passive Buzzer

The HNR‑1255 Series comprises through‑hole piezoelectric passive buzzers engineered for systems where supply voltage varies significantly across product variants or operating conditions. With an ultra‑wide 1–30 V drive range, a single component accommodates everything from single‑cell Li‑ion batteries (3.0–4.2 V) to 5 V logic rails, 12 V automotive accessory circuits, and 24 V industrial control buses — eliminating voltage regulation circuitry and simplifying global BOM management.

Manufactured by MEIDI in Jiangsu Province, these buzzers feature a 12.5 mm piezoelectric ceramic diaphragm — substantially larger than economy 9 mm variants — delivering ≥80 dB SPL at 4000 Hz with only ≤10 mA current draw. The 4000 Hz resonant frequency sits at the upper edge of the human auditory sensitivity peak (2–4 kHz), providing crisp, perceptible alerts with minimal power expenditure. Two mechanical variants share identical electrical performance: PA5.0 for flush PCB mounting and PA6.5 for elevated standoff or panel‑through applications.

Key Features

1–30 V ultra-wide drive compatibility — eliminates voltage regulation circuitry across single-cell Li-ion (3.0–4.2V), 5V logic, 12V automotive, and 24V industrial buses

4000 Hz auditory sweet-spot resonance — positioned for maximum human perceptibility with minimal power expenditure; positioned for maximum human perceptibility with minimal power expenditure"

Sub-10 mA current draw — at 5Vp-p, 4000 Hz square wave; enables direct MCU GPIO drive and extended battery life in wireless metering

12.5 mm expanded ceramic diameter — 54% greater diaphragm area than 9 mm variants; larger area theoretically improves acoustic efficiency

Dual lead-length platform — PA5.0 and PA6.5 share one electrical BOM; mechanical selection occurs at assembly without circuit redesign

Repair-tolerant PBT housing — withstands 260 ℃ wave soldering and 350 ℃ manual rework; 10-year batch traceability via lot code marking

Typical Applications

Smart utility meters — tamper alerts, communication-failure warnings, and low-battery chirps in gas, water, and electricity meters operating from 3.6V lithium primary cells

Portable medical diagnostics — test-completion tones, calibration-status beeps, and error alerts in handheld glucose monitors and pulse oximeters

Industrial sensor networks — fault alarms and threshold notifications on 12V/24V fieldbus-powered IoT nodes and remote telemetry units

Automotive aftermarket electronics — 12V accessory bus integration for parking sensors, tire-pressure monitors, and dashcam voice prompts

Battery-management systems — overcharge, thermal-runaway, and cell-imbalance audible warnings in Li-ion pack protection circuits

Security access control — door-forced-open, invalid-badge, and low-battery alerts in standalone 12V or PoE-extracted power configurations

FAQ

1. Can I drive the HNR-1255 Series directly from a 3.3V microcontroller GPIO pin?

Yes, within current limits. At 3.3Vp-p, the 12 nF capacitive load draws an estimated 6–7 mA at 4000 Hz — verify with actual measurement. SPL will be below the 5Vp-p specification; verify output with samples. For maximum output, use a 5V logic buffer or a transistor driver stage. The 1–30V operating range ensures the buzzer will not be damaged by 3.3V drive; it simply operates below rated acoustic output.

2. What is the practical difference between PA5.0 and PA6.5 in my PCB layout?

The electrical and acoustic performance is identical. The difference is mechanical: PA5.0 has standard lead length for flush mounting against the PCB surface), while PA6.5 provides extended leads for applications requiring greater standoff — such as front-panel insertion through a bezel, conformal-coating clearance, or thermal-airflow gaps. Both variants share the same PCB hole pattern and keepout zone; substitution requires no circuit or layout change.

3. How does the 4000 Hz frequency compare to 2700 Hz alternatives in real-world environments?

4000 Hz sits at the upper edge of the 2–4 kHz human auditory sensitivity peak, making it more perceptible than 2700 Hz in quiet to moderate ambient noise (offices, homes, medical facilities). However, 2700 Hz penetrates high-frequency industrial noise (motors, compressors above 3 kHz) more effectively. For indoor consumer, medical, and office environments, 4000 Hz provides crisper, more "urgent" tonal character. For factory floors and engine compartments, 2700 Hz may be preferable. The HNR-1255 Series is optimized for the former scenario.

4. Why is the capacitance tolerance ±40%, and how does this affect my driver design?

Piezoelectric ceramic capacitance varies with material batch, electrode area, and dielectric thickness. The 12 nF nominal with ±40% tolerance (7.2–16.8 nF) is typical for this class of buzzer. In practice, The sample batch measured 11.7--14.2 nF. For driver design, size the output stage for the specified capacitance tolerance range. For driver design, size the output stage for the worst-case 16.8 nF load at your switching frequency. At 4000 Hz, 16.8 nF requires ~13 mA peak charging current, still well within small-signal transistor capabilities. A 100 Ω series resistor can limit inrush current if GPIO drive is marginal.

5. Can I operate this buzzer continuously at 30V, and what is the expected lifetime?

The 30V maximum is a survival rating, not a continuous operating recommendation. At 30Vp-p, the piezoelectric element experiences maximum mechanical stress and dielectric heating. For continuous tone applications, MEIDI recommends limiting drive voltage or implementing duty cycle control to preserve electrode adhesion and ceramic integrity. Contact MEIDI for lifetime data under specific operating conditions. For continuous alarm applications, derating voltage or duty cycle extends lifetime proportionally.