Neoway N715-EA - Analog Audio Output (EAR;SPK)

N715-EA Hardware User Guide
Chapter 5 Application Interfaces
Copyright © Neoway Technology Co., Ltd. All rights reserved.
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⚫
B1 and B2 are ferrite beads used to filter out high-frequency noise. It is recommended to use
ferrite beads specifically for audio and the ferrite beads should have an impedance of 1800 Ω or
higher at 100 MHz and a DC resistance lower than 1.5 Ω. Dedicated audio magnetic beads are
recommended.
⚫
It is recommended to adopt an electret MIC that embeds dual capacitors (e.g.10 pF and 33 pF)
to filter out RF jamming and reduce TDD coupled noise.
PCB Design Guidelines
⚫
MIC_P and MIC_N traces should comply with the differential rules
⚫
Shield the audio traces with surrounded ground. Keep them 3 times widths away from other
signal traces.
⚫
Place RF filter capacitors close to the audio components or pins.
⚫
Keep traces far away from interference sources, such as DC-DC power supply.
5.4.2 Analog Audio Output
Signal
Pin
I/O
Function description
Remarks
EAR_N
21
AO
Earpiece output -
With a 32 Ω load, the maximum output power
is 50 mW. If the output power is not enough,
connect this interface to an external power
amplifier.
EAR_P
22
AO
Earpiece output +
SPK_P
109
AO
Speaker output +
Support differential output only, with built-in
class-AB or class-D power amplifier.
Peak output power:
Class AB: 600 mW@4.2V, with a 8 Ω load
Class D: 800 mW@4.2V, with a 8 Ω load
SPK_N
110
AO
Speaker output -
The external power amplifier should be added as required. The following shows the reference design
of the audio interface: