Download the JL ASxxxx-25C4 Series IC schematic diagram and datasheet. Explore detailed pin connections and specifications to enhance your repair.
The provided diagram showcases the JL Bluetooth IC (ACxxxxxx-25 series), a widely used integrated circuit in Bluetooth devices, FM radio systems, and audio amplifiers. Below, we break down each section and pin connection step by step, providing detailed insights into its functionality.
Overview of JL IC (ACxxxxxx-25 Series)
JL ICs in the ACxxxxxx-25 series are multifunctional chips used in wireless audio systems. They integrate various modules such as:
➔ Bluetooth module
➔ FM radio functionality
➔ Audio signal processing
➔ USB charging and data transfer
The IC's key features include:
➔ Bluetooth antenna connections.
➔ FM antenna functionality.
➔ USB and battery charging circuits.
➔ Microphone input and audio output.
➔ Button control for user interaction.
This makes it ideal for compact audio devices such as neckbands, TWS earbuds, and Bluetooth speakers.
Pin Configuration
Here’s a detailed explanation of each pin and its function based on the diagram:
Pin Number-Pin Name-Description
1 FM ANT Connection for the FM antenna, used for receiving radio signals.
2 SD CLK Clock signal for an SD card interface (memory section).
3 SD CMD Command signal for the SD card.
4 SD DAT Data signal for the SD card interface.
5 USBDM USB data line for data transfer (D-).
6 USBDP USB data line for data transfer (D+).
7 MIC Microphone input for capturing audio signals.
8 DACR Digital-to-analog converter (right channel output).
9 DACL Digital-to-analog converter (left channel output).
10 DACVDD Power supply for the DAC circuitry.
11 AGND Analog ground.
12 VCOM Voltage reference for analogue circuitry (commonly 3.3V).
13 LIN R Line input for the right channel.
14 LIN L Line input for the left channel.
15 AB/D Mode control pin for output configuration.
16 MUTE Mute control for the audio output.
17 ADKEY/LED PIN for connecting button control or indicator LEDs.
18 VMCU Power supply for the microcontroller.
19 BT AVDD Bluetooth circuit power supply.
20 FMIP FM input pins for processing antenna signals.
21 GND Ground pin.
22, 23 BT OSC1/OSC2 Connections for the 24 MHz Bluetooth crystal oscillator.
24 BT ANT Connection for the Bluetooth antenna, enabling wireless communication.
Circuit Explanation by Section
1. Power Supply Section
VCOM (Pin 12) provides a stable reference voltage (typically 3.3V) for analogue components.
DACVDD (Pin 10) and BT AVDD (Pin 19) supply power to the DAC and Bluetooth modules, respectively.
AGND (Pin 11) and GND (Pin 21) ensure a common ground reference for analogue and digital components.
Components:
C22, C23, C24: Bulk capacitors (typically 105/224) used to filter out voltage ripple and stabilize power lines.
Battery Connection: The IC supports input from a battery (4.2V to 5V), which powers the entire circuit.
2. Bluetooth Antenna and Oscillator Section
BT ANT (Pin 24): Connected to the Bluetooth antenna via a network of capacitors and inductors (C29, L5).
BT OSC1/OSC2 (Pins 22, 23): Connected to a 24 MHz crystal oscillator (Y1), which generates the clock signal necessary for Bluetooth communication.
This section is crucial for wireless data transmission and synchronization.
Components:
C1, C2: Small decoupling capacitors stabilize the oscillator's operation.
L3, L4, L5: Inductors fine-tune the signal quality for optimal Bluetooth performance.
3. FM Antenna Section
FM ANT (Pin 1): Connected to an external FM antenna to receive radio signals.
The FM signal is passed through a series of tuning components (L1, C28) to filter and amplify the signal.
Components:
L1: 180nH inductor to improve FM signal reception.
C28: 10pF capacitor for tuning the FM input signal.
4. USB and Charging Section
USBDM (Pin 5) and USBDP (Pin 6): These pins handle USB data transfer (D- and D+ lines).
The IC also supports charging functionality via the same USB connection, making it ideal for portable audio devices.
Components:
C24: Stabilizes the charging voltage.
USB signals are protected and filtered using appropriate bypass capacitors.
5. Audio Input/Output Section
LIN R (Pin 13) and LIN L (Pin 14): These are the line inputs for external audio sources.
DACL (Pin 9) and DACR (Pin 8): Outputs from the IC’s internal DAC, which are sent to speakers or external amplifiers.
MUTE (Pin 16): Used to mute the audio output, often controlled by a button or MCU logic.
Components:
C26: Coupling capacitor to block DC components in the audio output.
L4, L5: Output inductors to filter high-frequency noise.
6. Button Control and LED Indication Section
ADKEY/LED (Pin 17): Serves dual purposes:
Can be connected to buttons for controlling functions like play/pause, volume, or mode switching.
Can also drive indicator LEDs to show the status of Bluetooth pairing, charging, etc.
7. Microphone Section
MIC (Pin 7): This pin accepts input from an external microphone.
The microphone signal is processed internally by the IC for audio recording or hands-free calls.
Full Circuit Working
Power Initialization:
The IC receives power from a 4.2V-5V source (battery or USB).
Decoupling capacitors stabilize the voltage, ensuring proper operation of the analogue and digital sections.
Bluetooth Functionality:
The 24 MHz oscillator provides the clock signal for Bluetooth communication.
The Bluetooth antenna sends and receives data wirelessly.
FM Radio:
The FM antenna picks up radio signals, which are filtered and processed by the IC.
Audio Input and Output:
Audio signals can be input through LIN L/R or generated internally via Bluetooth or FM.
The DAC converts digital signals to analogue audio, which is amplified and sent to speakers or headphones.
User Interaction:
Buttons connected to the ADKEY pin allow the user to control various functions.
LEDs indicate system status.
Applications
➔ Bluetooth speakers.
➔ Neckbands and TWS earbuds.
➔ FM radios with Bluetooth capability.
➔ Audio amplifiers with USB charging.