Features
Output Short Circuit Protection
Thermal Overload Protection
Stereo filterless Class D operation
Spread spectrum modulation
Ground referenced Headphone Drivers
I
2C Control Interface
32-step input volume control
Output volume control
Minimum external components
Click and Pop suppression
Micro-power shutdown
Available in space-saving 36–bump µSMD package
Single supply operation
RF suppression
Description The LM49250 is a fully integrated audio subsystem designed for stereo cell phone applications. The LM49250 combines a 2.4W/Ch
stereo class D speaker amplifiers with a 45mW/Ch stereo ground referenced headphone amplifier, a class AB earpiece amplifier,
National 3D enhancement, volume control, and an input mixer into a single device. The filterless class D amplifiers deliver
1.2W/Ch into an 8Ω load with <1% THD+N from a 5V supply.
The LM49250 features a new circuit technology that utilizes a charge pump to generate a negative supply voltage. This allows
the headphone outputs to be biased about ground, thereby eliminating the output-coupling capacitors.
For improved noise immunity, the LM49250 features fully differential left, right and mono inputs. The three inputs can be
mixed/multiplexed to any output combination of the loudspeaker, headphone or earpiece amplifiers. The left and right differential
inputs can be used as separate single-ended inputs, mixing multiple stereo audio sources. The mixer, volume control, and
device mode select are controlled through an I
2C compatible interface.
Output short circuit and thermal overload protection prevent the device from being damaged during fault conditions. Superior
click and pop suppression eliminates audible transients on power-up/down and during shutdown.
Key Specification
| ■
Power Output at VDD = 5V
|
|
| Speaker:
RL = 4Ω, THD+N
≤ 1%
RL = 4Ω, THD+N
≤ 10%
RL = 8Ω, THD+N
≤ 1%
|
1.97W/Ch
2.4W/Ch
1.2W/Ch
|
| Headphone:
RL = 16Ω, THD+N
≤ 1%
RL = 32Ω, THD+N
≤ 1%
|
41mW/Ch
45mW/Ch
|
| Earpiece:
RL = 16Ω, THD+N
≤ 1%
RL = 32Ω, THD+N
≤ 1%
|
170mW
90mW
|
| ■
Shutdown Current
|
0.1μA
|
| ■
Efficiency at 5V, 1W into 8Ω
|
87%
|
| ■
Efficiency at 3.6V, 500mW into 8Ω
|
85%
|
Applications
Mobile phones
Portable Navigation Devices
Portable Media Players
|
|
