SMA 21 P10 Sonitron Loudspeaker or Buzzer (Other) In Stock
Sonitron SMA 21 P10 is a PCB-mount continuous internal piezo buzzer operating from 1.5 V to 24 V DC, producing 85 dB sound pressure at a resonant frequency range of 2805 to 3795 Hz. Its wide supply voltage range and self-driven internal oscillator make it ideal for alarm, notification, and safety-warning applications across industrial and consumer devices.
- Manufacturer
- Sonitron
- Package
- Other
- Pin Count
- 2
- Lifecycle
- ACTIVE
- Datasheet
- SMA 21 P10 Datasheet PDF
- Category
- Loudspeaker or Buzzer
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Wide 1.5 V to 24 V DC supply range enabling use across battery-powered and mains-derived logic-level systems without external regulation
- 85 dB sound output level at close range for clearly audible alarms and notifications in noisy industrial environments
- Internal oscillator with 2805–3795 Hz frequency sweep for continuous self-driven tone generation without external drive circuitry
- PCB-mount form factor for direct board assembly, reducing wiring harness cost and improving reliability
- Continuous tone mode suited for persistent fault alarms in safety-critical equipment and industrial control panels
Applications
The SMA 21 P10 piezo buzzer is used in industrial control panels, home appliances, and medical alert devices where a loud, self-driven audible alarm is needed without complex driver circuitry. Its 1.5 V to 24 V operating range allows direct integration with microcontroller GPIO pins, relay outputs, and 24 V industrial logic systems on the same board. Security systems, smoke detectors, and process control equipment commonly employ this buzzer to signal fault conditions with an 85 dB continuous tone audible over ambient factory noise.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
No known alternates. Submit an RFQ and our team can suggest alternatives.
Frequently Asked Questions
Can the SMA 21 P10 buzzer operate directly from a 3.3 V microcontroller GPIO pin without an external driver transistor?
The SMA 21 P10 operates across 1.5 V to 24 V DC, so a 3.3 V GPIO pin can power it directly if the pin can source sufficient current for the piezo element. At 3.3 V the buzzer will produce a tone in the 2805–3795 Hz range, though sound pressure may be lower than the rated 85 dB, which is typically measured at the nominal voltage. For guaranteed 85 dB output, driving at 5 V or higher within the 24 V maximum is recommended.
What frequency range does the SMA 21 P10 cover, and why is that range selected for audible alarm applications?
The SMA 21 P10 sweeps from 2805 Hz to 3795 Hz, a band centered near 3 kHz where human hearing is most sensitive according to ISO 226 equal-loudness contours. This frequency selection maximizes perceived loudness at a given 85 dB SPL rating, making alarms effective even in environments with high low-frequency background noise such as factory floors with rotating machinery producing noise below 1 kHz.
How does the SMA 21 P10 compare to an externally-driven passive piezo buzzer for a 24 V industrial panel alarm application?
Unlike passive piezo buzzers that require an external PWM signal generator operating at the correct 2805–3795 Hz frequency, the SMA 21 P10 includes an internal oscillator, simplifying firmware and reducing BOM components by eliminating the need for a dedicated timer peripheral. At 24 V the self-driven internal circuit delivers the full 85 dB output, matching the loudness of externally-driven passive elements while allowing direct switch-on control through a relay or open-collector output in the industrial panel.
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