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Class G amplifier enables piezoelectric drive with minimum support components

Sunnyvale, Calif. — Maxim Integrated Products introduced the MAX9788, single-channel, Class G amplifier designed to drive the high capacitive load of piezoelectric speakers. The MAX9788 integrates an inverting charge-pump power supply, which provides up to 16 Vp-p voltage drive from a single lithium-ion (Li+) battery. This voltage doubles the available supply without using any inductors. The amplifier comes in a 2 x 2.5-mm UCSP package and operates over the -40°C to 85°C temperature range.

The MAX9788 uses charge-pump technology to generate up to 16 Vp-p voltage drive from a single Li+ battery with minimal external support components. Li+ batteries typically generate 4.2 V maximum and operate down to 3.0 V as the battery discharges. Using an inverting charge pump, similar to the company's DirectDrive technology, the MAX9788 doubles the available supply without using any inductors. Two small and inexpensive ceramic capacitors are the only external components required to generate the inverted supply. With the creation of the second negative supply, the MAX9788's amplifier can operate from a dual supply of up to ±5.5 V, enabling the amplifier to output nearly 20 Vp-p.

In typical applications, the amplifier can operate from either a regulated 5V supply or directly from the Li+ battery, in either case generating sufficient voltage to drive a piezoelectric speaker. Not only can the MAX9788 generate the voltage required for ceramic speakers, but it also delivers the necessary current. The MAX9788 uses a larger charge pump than typical DirectDrive amplifiers. This charge pump can deliver up to 500 mA of continuous current, which allows the amplifier to maintain flat frequency response at high frequencies.

Availability: Samples available
Pricing: Begins at $0.80 each in 1,000-piece quantities
Data Sheet: http://datasheets.maxim-ic.com/en/ds/MAX9788.pdf

Maxim Integrated Products, 408-737-7600, www.maxim-ic.com

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