The modern car Bluetooth player (QC 3.0 fast charging version) adopts typical solutions of CX8822, CX8825 and 5V3A car chargers.

The modern in car Bluetooth player (QC 3.0 fast charging version) has the main functions that low-end vehicles with only FM radio have, such as Bluetooth playback, USB flash drive playback, hands-free communication, and other functions that high-end vehicles only have. It also comes with practical functions such as QC 3.0 fast charging output and battery voltage monitoring and warning.

5v3a car charger solution, see also CX8825 disassembly eva1uation: Korean Hyundai car Bluetooth player

CX8822 is a synchronous rectification and voltage reduction chip from Chengxin Micro, with an input range of 7.5V-32V and supporting a maximum 3A continuous current output; CX8822 is designed specifically for 5V voltage output. When the system output voltage exceeds 6.5V, the chip will forcibly stop output to avoid damage to subsequent devices.

Supplement:

The 0.030 Ω large chip resistor (RZ1) next to the chip is the sampling resistor used to detect the output current. From the technical manual, it can be inferred that the output current of this CX8822 is limited to 3.1A.

This CX8822 is not only used for 5V USB port, but also responsible for supplying other chips on the board (main control chip, FM transmitter chip, etc.)

5v3a car charger solution, see also CX8825 disassembly eva1uation: Korean Hyundai car Bluetooth player

CX8825 Overview:

The CX8525 is an input 8V-30V with built-in High side and Low side, which can support a continuous output current of 3.1A. It has high-performance load response and input voltage response capabilities, as well as constant current and precise constant voltage control loops to achieve load adjustment rate and linear adjustment rate.

CX8525 does not require external compensation and can rely on its built-in stable loop to achieve constant current and constant voltage control

CX8525 is a constant voltage, constant current, and step-down DC-DC converter with minimal application, excellent performance, and stability and reliability

CX8825 Features:

• Input voltage 8V-30V

• Input with overvoltage protection 32V

• Output voltage 3V-20V adjustable

• Built in High side

• Built in Low side

• Can support 3.1A continuous output current

• Built in constant current and constant voltage control loops

• Constant pressure accuracy ± 2%

• Supports 100% duty cycle

• No external compensation required

• 135k Hz fixed switching frequency

• Support for MLCC

• Ultra simple application circuit

• Short circuit protection (SCP), overheat protection (OTP), overcurrent protection (OCP), overvoltage protection (OVP)

• SOP-8L packaging form

CX8825 applies to:

• car charger 

• Illuminating lamp

• Portable device power supply