Features
| • | 3W Output into 8Ω at 5V with THD+N = 1% |
| • | Selectable spread spectrum mode reduces EMI |
| • | 80% Efficiency |
| • | Independent Regulator and Amplifier Shutdown Controls |
| • | Dynamically Selectable Regulator Output Voltages |
| • | Filterless Class D |
| • | 3.0V – 5.5V operation |
| • | Low Shutdown Current |
| • | Click and Pop Suppression |
Description The 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 gain of the LM48511 is set by external resistors, which allows independent gain control from multiple sources by summing
the signals. Output short circuit and thermal overload protection prevent the device from damage during fault conditions.
Superior click and pop suppression eliminates audible transients during power-up and shutdown.
Key Specification
| ■
Quiescent Power Supply Current
|
|
| VDD = 3V
VDD = 5V
|
9mA (typ)
13.5mA (typ)
|
| ■
PO at VDD = 5V, PV1 = 7.8V
RL = 8Ω, THD+N = 1%
|
3.0W (typ)
|
| ■
PO at VDD = 3V, PV1 = 4.8V
RL = 8Ω, THD+N = 1%
|
1W (typ)
|
| ■
PO at VDD = 5V, PV1 = 7.8V
RL = 4Ω, THD+N = 1%
|
5.4W (typ)
|
| ■
Shutdown Current at VDD = 3V
|
0.01μA (typ)
|
Applications
| • | GPS |
| • | Portable media |
| • | Cameras |
| • | Mobile Phones |
| • | Handheld games |
|
|
