NCP2821
http://onsemi.com
17
PCB Layout Information
NCP2821 is suitable for low cost solution. In a very small
package it gives all the advantages of a Class−D audio
amplifier. The required application board is focused on low
cost solution too. Due to its fully differential capability, the
audio signal can only be provided by an input resistor. If a
low pass filtering function is required, then an input
coupling capacitor is needed. The values of these
components determine the voltage gain and the bandwidth
frequency. The battery positive supply voltage requires a
good decoupling capacitor versus the expected distortion.
When the board is using Ground and Power planes with
at least 4 layers, a single 4.7 F filtering ceramic capactior
on the bottom face will give optimized performance.
A 1.0 F low ESR ceramic capacitor can also be used with
slightly degraded performances on the THD+N from 0.06%
up to 0.2%.
In a two layers application, if both V
p
pins are connected
on the top layer, a single 4.7 F decoupling capacitor will
optimize the THD+N level.
The NCP2821 power audio amplifier can operate from
2.5 V until 5.5 V power supply. With less than 2% THD+N,
it delivers 500 mW rms output power to a 8.0 load at
V
p
=3.0 V and 1.0 W rms output power at V
p
= 4.0 V.
Figure 47. Top Layer
Note: This track between Vp pins is only needed when a 2 layers board is used. In case of a typical
4 or more layers, the use of laser vias in pad will optimize the THD+N floor. The demonstration
board delivered by ON Semiconductor is a 4 Layers with Top, Ground, Power Supply and Bottom.
Note
