Piezo sounder driver enables higher volume with lower currents

Integrating a multi-mode charge pump boost converter, the PAM8904 from Diodes drives piezoelectric sounders at up to 18Vpp from a 3V power supply.

Bringing higher volume at a lower operating current and with a wide input signal range of 20Hz to 300kHz, the piezo sounder driver is suited to a variety of battery powered applications, including medical systems, alarm clocks and security devices. Operating from a 2.3 to 5.5V supply at a fixed frequency of 1MHz, the PAM8904 will drive a sounder load of up to 15nF, providing a 9V output and a minimal component footprint. Able to operate in 1x, 2x and 3x modes, the charge pump enables designers to select from three different piezo sound pressure levels. With a built-in automatic shutdown and wake up function, the sounder driver helps to keep current consumption low and battery life long. Active current consumption for example is just 300µA in 1x mode, with an input voltage of 3V, input frequency of 4kHz, driving a 15nF piezo. In shutdown mode, quiescent current is less than 1µA. Product reliability is aided by the PAM8904's low inrush current, low EMI drive technology and a variety of integrated protection features. These comprise thermal shutdown, over current, over voltage and under voltage lock-out protection.