Explore All Essential information on the 69A2 IC circuit and its components. Understand how it operates with detailed sections and helpful guides. Explore the 69A2 IC and 6969A2 IC with 16 pins. Find everything you need about the same circuit board and its features on our website.
69A2 IC Circuit Details
Component Details And Connection
Switches
Switch Type: 4-Leg Mini SMD Type (Power ON/OFF, Music Change, Volume Control)
Install Quantity: 3 (1 for Power ON/OFF, 2 for Music Change/Volume Control)
Switch Model Number: 440.8 mm
Switch Working
These switches are used to control various functions of the neckband.
Power Switch: When pressed, it powers the circuit on or off by connecting the battery’s voltage to the internal control IC.
Music Change/Volume Control Switches: These two switches send commands to the control IC to change tracks or adjust the volume. The exact function is determined by how long you hold down the button or how many times you press it.
Switch Connection
These switches are connected directly to the microcontroller pins (AC20BP09421 - 69A2 IC). The power switch connects to the battery power line, and the volume/music switches connect to input pins configured for controlling audio functions.
Charging Connector
C/C Type: 5V, 2A, 5-Pin SMD Micro Type B Connector
C/C Connection
VCC- +5V Input
DM – USB data negative pin for charging IC communication
DP – USB data positive pin for charging IC communication
ID - Short to Gnd
GND – Ground connection
C/C Working
The charging connector is used to connect an external charger to the neckband’s internal battery. The Vbat pin supplies the charging voltage directly to the battery management system, which regulates the charging process. The USB-dm and USB-dp are used for data communication (like power negotiation), while GND is the common ground.
C/C Connection
VCC: Connects to the IC 3 Number Pin (LDO-IN) (B+)
USB-dm, USB-dp: Communicates with the charging IC for regulated charging control.
ID: Connect To The GND
GND: Connects to the ground line (B-).
Crystal IC
Crystal Frequency: 24.000 MHz
Crystal IC Pin: 2-Pin
Type: SMD
Crystal IC Working
The crystal oscillator provides a stable clock signal required by the AC20BP09421 - 69A2 control IC to manage audio processing and Bluetooth functions. The frequency is crucial for maintaining synchronization in digital operations, like decoding audio streams.
Crystal IC Connection
Pin 1 & Pin 2: Directly connected to the crystal input pins of the AC20BP09421 - 69A2 IC. These connections help the IC maintain accurate time-based operations.
Main IC*ontrol IC*Audio Generator IC
IC Number: AC20BP09421 - 69A2
IC Brand: JL (Jieli)
Pin Count: 16 Pins
Main Working
This IC is the brain of the neckband system. It manages all audio generation, control functions, power regulation, Bluetooth connectivity, and audio signal processing. The IC handles decoding digital audio streams (usually Bluetooth) and converting them into analogue signals to drive the headphone speakers.
Power Management
The IC controls when to draw power from the battery and manages the charging process.
Audio Processing
It processes the incoming digital audio signals and generates analogue signals to drive the left and right speakers.
Microphone Input Processing
It manages the input from the microphone and processes it to send outgoing audio data via Bluetooth.
Control Interface
It monitors the user input from the switches (e.g., volume control, and music changes) and controls audio output accordingly.
Main IC Connection
Power Pins: Connected to the battery's B+ and B-.
Audio Output Pins (L+, L-, R+, R-): Connected to the left and right headphone speakers.
Microphone Pins: Connected to the microphone for audio input.
Control Pins: Connected to the switches for user interface control (power, volume, music).
Battery Section
Battery Type: Rechargeable Li-Polymer Battery
Battery Capacity: 3.7V, 200mAh
Battery Backup: 12 hours (dependent on usage And Battery Capacity)
Battery Working
The battery provides the necessary power to the neckband circuit. It powers all the active components, including the AC20BP09421 - 69A2 IC, speakers, LED indicators, and Bluetooth functionality. The battery backup is around 12 hours, which varies depending on audio playback volume, Bluetooth activity, and other factors.
Battery Connection
B+ and B- Pins: These are connected to the power input pins of the AC20BP09421 - 69A2 IC and charging management IC.
Charging Input: The battery is charged through the charging connector via the Vbat and GND lines.
Microphone
Mic Model: SH-018
Mic Pin Count: 2 Pins
Mic Working
The microphone captures the user's voice for phone calls or voice commands. The audio signal from the microphone is processed by the control IC (AC20BP09421 - 69A2) and sent via Bluetooth to the connected device (like a smartphone).
Mic Connection
Pin 1 and Pin 2: Connected to the microphone input pins on the AC20BP09421 - 69A2 IC.
LED Indicators
Red LED: Indicates charging status (on when charging).
Blue LED: Indicates power on and Bluetooth connection status (blinks when in pairing mode or when connected).
LED Indicator Working
The red LED lights up when the neckband is charging.
The blue LED flashes during Bluetooth pairing and stays on once connected to a device. It also blinks when the device is powered on but not connected to a Bluetooth device.
LED Indicator Connection
Red LED: Connected to the charging IC, lights up when the device is charging.
Blue LED: Connected to the control IC (AC20BP09421 - 69A2), which controls its flashing behaviour based on Bluetooth activity.
Headphone Speaker Connection
Headphone Working
The left and right audio signals are output by the AC20BP09421 - 69A2 IC and drive the left and right speakers of the neckband. These signals are analogue audio signals that create the sound heard in the headphones.
Headphone Connection
L+, L- Pins: Connected to the left speaker.
R+, R- Pins: Connected to the right speaker.
Circuit All Section Working
Power ON/OFF
The user presses the power switch, which triggers the control IC to power the entire circuit.
The battery provides 3.7V to the IC, starting the internal clock (using the 24.000 MHz crystal) to run the system.
Bluetooth Pairing
When powered on, the control IC manages Bluetooth pairing, indicated by the blue LED flashing.
Once paired, the IC handles audio streaming from the paired device to the speakers.
Audio Processing
The control IC receives a digital audio signal from the paired Bluetooth device.
It processes the digital signal and converts it into analogue signals, which are then sent to the left and right speakers via the L+, L-, R+, and R- pins.
Volume/Music Control
The user presses the volume control or music change buttons. These inputs are received by the control IC, which adjusts the audio signal or changes the track accordingly.
Microphone Operation
When the microphone is used (e.g., during a phone call), the microphone captures the user's voice and sends the audio signal to the control IC.
The IC processes the microphone signal and sends it to the paired device over Bluetooth.
Charging
When a 5V charger is connected to the charging connector, the battery is charged via the Vbat and GND lines.
The red LED lights up, indicating charging, and the control IC manages the charging current and stops charging once the battery is full.
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