Product Info
Table Of Contents
- About the Document
- Contents
- Table Index
- Figure Index
- 1 Introduction
- 2 Product Concept
- 3 Application Interfaces
- 3.1. General Description
- 3.2. Pin Assignment
- 3.3. Pin Description
- 3.4. Power Supply
- 3.5. Turn on and off Scenarios
- 3.6. VRTC Interface
- 3.7. Power Output
- 3.8. Battery Charge and Management
- 3.9. USB Interfaces
- 3.10. UART Interfaces
- 3.11. (U)SIM Interfaces
- 3.12. SD Card Interface
- 3.13. GPIO Interfaces
- 3.14. I2C Interfaces
- 3.15. I2S Interfaces
- 3.16. SPI Interface
- 3.17. ADC Interfaces
- 3.18. LCM Interfaces
- 3.19. Touch Panel Interfaces
- 3.20. Camera Interfaces
- 3.21. Sensor Interfaces
- 3.22. Audio Interfaces
- 3.23. Emergency Download Interface
- 4 Wi-Fi and BT
- 5 GNSS
- 6 Antenna Interfaces
- 7 Electrical, Reliability and Radio Characteristics
- 8 Mechanical Dimensions
- 9 Storage, Manufacturing and Packaging
- 10 Appendix A References
- 11 Appendix B GPRS Coding Schemes
- 12 Appendix C GPRS Multi-slot Classes
- 13 Appendix D EDGE Modulation and Coding Schemes
- IC & FCC Requirement
Smart LTE Module Series
SC66 Hardware Design
SC66_Hardware_Design 87 / 139
3.22.3. Reference Circuit Design for Headphone Interface
20K
MIC_GND
MIC2_P
HPH_L
HS_DET
HPH_R
HPH_REF
33pF
Module
R1
0R
6
3
4
5
2
1
33pF 33pF
C3
C4 C5
F3
F2
F1
D1 D2 D3
D4
F4
R2
R3
0R
D0
Figure 33: Reference Circuit Design for Headphone Interface
3.22.4. Reference Circuit Design for Loudspeaker Interface
EARP
EA
RN
F2
SPK_P
SPK_M
33pF
33pF
C1
C2
F1
Module
D1 D2
Figure 34: Reference Circuit Design for Loudspeaker Interface
3.22.5. Audio Interfaces Design Considerations
It is recommended to use the electret microphone with dual built-in capacitors (e.g. 10pF and 33pF) for
filtering out RF interference, thus reducing TDD noise. The 33pF capacitor is applied for filtering out RF
interference when the module is transmitting at EGSM900. Without placing this capacitor, TDD noise
could be heard. The 10pF capacitor here is used for filtering out RF interference at DCS1800. Please note
that the resonant frequency point of a capacitor largely depends on the material and production technique.
Therefore, customers would have to discuss with their capacitor vendors to choose the most suitable