66B4 IC Audio Circuit Board Details And Working All Section

Discover the intricate details and workings of the 66B4 IC audio circuit board and HAA9811 IC. Explore all sections for a comprehensive understanding.

AC6966B Board Details
AC6966B4 Board  Font view image

Main IC & CPU Section (66B4 IC)

IC No : BPXXXXX - 66B4
IC Brand - JL
IC Pins: 32 Pin
The heart of this circuit is the 66B4 IC (from JL, BPXXXXX series). This IC is a 32-pin microcontroller that handles all the primary audio processing tasks. It manages the overall functions of the audio amplifier board, including controlling the audio input, managing volume, switching tracks, and powering on/off the device. The CPU section is critical for processing the digital signals received from the audio source (such as a phone, MP3 player, or Bluetooth device) and converting them into signals that the amplifier can enhance.

How it works:

The 66B4 IC receives digital audio signals from external sources through its input pins.
It processes these signals, applies audio filters, and sends them to the audio amplifier ICs.
It also controls the device’s power functions, interacts with the user via buttons, and communicates with other sections (like the battery and LED indicators).
This IC ensures that the music is played correctly, manages volume levels, and coordinates the overall functionality of the board.

Audio Amplifier Section

Audio Amplifier Total Install ICs: 2
IC Number: HAA9811
IC Pin: 10 Pin
This board features two audio amplifier ICs, each with 10 Pin HAA9811. These ICs are responsible for boosting the processed audio signals from the 66B4 IC to a level that can drive the speakers connected to the board.

How it works:

The processed audio signals from the main IC are sent to the HAA9811 ICs.
Each HAA9811 IC amplifies the signals separately for the left (L+, L-) and right (R+, R-) audio channels, providing stereo output.
The amplified signals are then sent to the speakers (headphones or external speakers) connected to the board.
These amplifier ICs ensure that the sound output is clear, loud, and well-balanced between the left and right channels.

Switch Section

The board has 5 mini SMD-type switches for controlling various functions. These switches are responsible for:

Mute: Instantly silencing the audio.
Pause: Stopping the audio playback.
Music Change or Volume Control: Two buttons for changing tracks and adjusting volume (increase/decrease).
Power On/Off: A switch to turn the device on or off.

How it works:

When the user presses any switch, it sends a signal to the 66B4 IC.
The IC interprets the signal and performs the corresponding action, such as muting the sound, pausing the music, adjusting the volume, or turning the device on/off.
These switches allow the user to easily control the audio output and manage the device without needing a display or complex interface.

Crystal Frequency Section

This section includes a 24.000M crystal oscillator (2-pin SMD type), which provides the clock signal necessary for the 66B4 IC to function properly.

How it works:

The crystal oscillator generates a precise timing signal that the 66B4 IC uses to synchronize its operations.
This ensures that the audio processing, button inputs, and other functions are timed correctly.
Without this crystal oscillator, the IC would not be able to maintain proper timing, resulting in errors in audio playback or control functions.

Battery Section

Battery Type: Rechargeable Li-Polymer Battery 
Battery Model: Universal Any Number 
Battery Rate Capacity: 3.7v,2000mAh
Battery Backup Hours: 12 (Depend On Battery Capacity Rate)
This board uses a rechargeable Li-Polymer battery to power all its components. The battery typically has a rating of 3.7V, 2000mAh, providing about 12 hours of operation (depending on the battery capacity and usage).

How it works:

The battery supplies power to the entire board, including the 66B4 IC, amplifier ICs, and other components.
It is connected through B+ and B- terminals, ensuring that the board has a stable power supply during operation.
The battery section ensures that the board can operate wirelessly for an extended period, making it ideal for portable audio devices.

Charging Section

Charging Connector Type: Type B / C
Charging Connector Function: 5 Connection Lage(Vbat, USB-dm, USB-dp, gnd, vddio +3.3v)
Charging IC Number: 4054
Charging IC Pin: 6 Pin (5 Pin Working)
Charging Indicator LED Color: Red
Charging Input Voltage: 5 Voltage
Charging Input Ampere: 2 Ampere
Charging Time Load Voltage: 3.8V
Charging Time Load Ampere: 0.2A-0.9A
The board includes a charging connector (Type B/C) for recharging the Li-Polymer battery. The charging process is managed by a 4054 IC, which has 6 pins (5 of which are active).

How it works:

When you connect a charger, the charging IC 4054 regulates the voltage and current flowing into the battery.
It controls the charging process, ensuring that the battery is charged efficiently without overcharging or overheating.
The charging IC maintains the input voltage at 5V and manages the current flow between 0.2A to 0.9A during charging.
The charging process is indicated by a red LED, which turns on while charging is in progress.
This section ensures safe and efficient charging of the battery, extending its life and ensuring that the device can be recharged quickly.

LED Section

The board uses LED indicators to provide visual feedback to the user. There are two main LEDs:

Red LED: Indicates when the device is charging.
Blue LED: Indicates when the device is powered on or when audio is playing (usually blinks during playback).

How it works:

The 66B4 IC controls the LEDs, turning them on/off or making them blink based on the device’s status.
When the device is charging, the red LED turns on to indicate that the battery is being charged.
When the device is powered on, the blue LED starts blinking to show that the audio amplifier is active and music is playing.
AC6966B4 Board  Back view image

Connection Points

Here’s how the various connection points on the board work:

B+, B-: These points connect to the battery terminals, providing power to the board.
L+, L-: These points connect to the left speaker (or headphone) to output the amplified audio signal for the left channel.
R+, R-: These points connect to the right speaker for the right channel output.
M+, M-: These points might be used for connecting microphones or additional control signals related to audio processing.
D+ and D-: These points are typically for USB data lines (used when the device also supports data transfer or firmware updates via USB).
G, IO, V+: These could be general-purpose input/output (GPIO) pins or power lines for additional external components.
OL, IL: Likely represent input/output lines for auxiliary connections or other external audio input sources.
GND, KEY, IR: GND is the ground connection, while KEY might be for button inputs and IR could indicate support for an infrared remote control.

Full Circuit Working

Power On: The user presses the power switch, sending a signal to the 66B4 IC, which initializes the board and turns on the blue LED.

Audio Input: The 66B4 IC receives audio signals (either through Bluetooth, AUX, or another input) and processes them.

Amplification: The processed signals are sent to the two HAA9811 amplifier ICs, which amplify the left and right channel signals.

Speaker Output: The amplified signals are sent to the connected speakers (L+, L- for the left speaker, R+, R- for the right speaker), producing sound.

User Controls: The user can mute, pause, or change tracks using the switches. These commands are processed by the 66B4 IC, which adjusts the audio output accordingly.

Battery Management: The battery supplies power during playback. When the battery is low, the device can be recharged via the Type B/C charging connector, with the 4054 IC managing the charging process.

LED Indicators: The red LED shows the charging status, while the blue LED indicates the power on/audio playback status.

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