MAS6240C2HP06 Low Noise/EMI Piezo Buzzer Driver

The MAS6240 is a piezo driver device that can drive outputs up to 18Vpp from a 3V supply. An internal three-mode charge pump generates a boosted supply voltage for the piezo driver. To adjust the piezo element sound volume, the charge pump can operate in either 1x, 2x or 3x mode. In 1x mode the output voltage is the same as the input voltage while in 2x or 3x mode the input voltage is boosted accordingly.

The MAS6240 is an easy and low-cost peizo driver solution since only 4 small value capacitors are needed in addition to the sound element. No inductors are required. This design also causes significantly less disturbance to the surrounding circuits making it an ideal choice for sensitive designs. Its charge pump switches at 1MHz, allowing the use of external capacitors as small as 100nF.

Control logic switches the charge pump on at the first rising signal of the digital input (DIN) pin. The switch-off signal is generated while the signal at DIN has been low for 50ms. The piezo driver isenabled at a second rising edge of a pulse at DIN and the signal is transferred to piezo output VO1. The same signal is inverted into output VO2 for the differential output.

A continuous high logic level at the DIN input causes the charge pump to be turned ON but leaves the audio amplifier disabled. In that state the charge pump output can be used to power the external LEDs or any other external circuit. The output voltage is stillselectable in three steps.In "disabled" mode (DIN has been low for 15ms typically) all functional blocks are switched off to achieve a quiescent current of less than 1μA.