LM48511 integrates a boost converter with a high efficiency Class D audio power amplifier to provide 3W continuous power into an 8Ω speaker when operating from a 5V power supply. When operating from a 3V to 4V power supply, the LM48511 can be configured to drive 1 to 2.5W into an 8Ω load with less than 1% distortion (THD+N). The Class D amplifier features a low noise PWM architecture that eliminates the output filter, reducing external component count, board area consumption, system cost, and simplifying design. A selectable spread spectrum modulation scheme suppresses RF emissions, further reducing the need for output filters. The LM48511's switching regulator is a current-mode boost converter operating at a fixed frequency of 1MHz. Two selectable feedback networks allow the LM48511 regulator to dynamically switch between two different output voltages, improving efficiency by optimizing the amplifier's supply voltage based on battery voltage and output power requirements. The LM48511 is designed for use in portable devices, such as GPS, mobile phones, and MP3 players. The high, 80% efficiency at 5V, extends battery life when compared to Boosted Class AB amplifiers. Independent regulator and amplifier shutdown controls optimize power savings by disabling the regulator when high output power is not required.
The LM48511 integrates a boost converter with a high‑efficiency Class D audio power amplifier, delivering up to 3 W continuous into an 8 Ω speaker from a 5 V supply. It features selectable spread‑spectrum modulation to suppress RF emissions and reduce the need for external output filters, making it suitable for portable devices such as GPS units, mobile phones, and MP3 players.
The device includes independent regulator and amplifier shutdown controls, low‑shutdown current, and click‑and‑pop suppression. Pin descriptions, typical application circuits, and electrical characteristics are provided for designers to implement the amplifier in their products.
| Efficiency | 80 % at 5 V |
|---|---|
| Quiescent Power Supply Current (FF mode) | 13.5 mA max |
| Supply Voltage Range | 3.0 V to 5.5 V |
The quiescent power‑supply current is 13.5 mA maximum in fixed‑frequency mode.
The amplifier achieves about 80 % efficiency at a 5 V supply.