Diodes Incorporated introduced the PAM8904 piezo-sounder driver with integrated multi-mode charge pump boost converter. The PAM8904 is capable of driving piezoelectric sounders up to 18 VPP from a 3 V power supply. With its wide input signal range of 20 Hz to 300 kHz and ability to deliver high volume at a low operating current, this driver is suitable for a variety of battery-powered applications, including medical systems, alarm clocks and security devices.
Operating from a 2.3 V to 5.5 V supply at a fixed frequency of 1 MHz, the PAM8904 is able to drive a sounder load of up to 15 nF, providing a 9 V output with a minimal component footprint. The charge pump also enables designers to select three different piezo sound pressure levels by offering 1x, 2x and 3x operating modes.
The sounder driver helps to keep current consumption low and battery life long by employing built-in automatic shutdown and wake-up functions. For example, active current consumption is just 300 μA in 1x mode, with an input voltage of 3 V, input frequency of 4 kHz and driving a 15 nF piezo. In shutdown mode, quiescent current is less than 1 μA.
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.
