Download the BoAt Neckband AB1561 CPU schematic diagram and pinout. And repair Your Rockerz 255 Pro Bluetooth Headphones. Boat Rockerz 255 Pro Plus - AB1561M, B1562A, AB1562F All pins Working Details.
AB1562A/B/F Chipset: The main Bluetooth and power management IC.
Audio Circuitry: Microphone, speaker, and audio input/output.
Power Management and Battery Charging: A charging IC, battery, and related connections are included.
Touch Sensor and LED Indicators: These are for user input and status display.
External Connectors: USB or other interfaces for charging and communication.
RF and Bluetooth Connectivity: Handles wireless communication.
Detailed Explanation of Components and Connections
1. Main Chip: AB1562A/B/F
This chip serves as the heart of the circuit. It handles Bluetooth communication, power management, and audio processing.
Key Pins and Their Functions:
VBAT (Pin 17): This connector connects to the battery's positive terminal and provides the main power supply to the IC.
VSYS (Pin 16): System power output, used for other parts of the circuit.
VBUS (Pin 18): Connects to the charging input (e.g., USB). It powers the system during charging.
UART_TX (Pin 32) & UART_RX (Pin 31): Used for debugging or communication with external devices.
XTAL_IN1/XTAL_IN2 (Pins 2 & 3): Connects to a 26 MHz crystal oscillator for clock generation.
AU_VIN0_P/N, AU_VIN1_P/N (Pins 24-25, 22-23): Audio input pins for microphones.
AU_HP_RP/RN (Pins 29-30): Audio output for speakers.
MIC_BIAS0/1 (Pins 28, 21): Provides bias voltage for the microphones.
GPIOs (Pins 35-42): General-purpose pins for controlling LEDs, switches, or other peripherals.
ISINK0/1 (Pins 12-13): Current sinks used to drive LEDs for status indication.
SYSRSTB (Pin 4): System reset input.
2. Battery and Charging
Battery Connection: The battery is connected to the VBAT pin through protection circuitry.
Charging IC: A dedicated IC (not fully labelled but present in the schematic) manages to charge via the USB connector. It monitors VBAT and VBUS voltages to ensure safe charging.
NTC (Negative Temperature Coefficient) Resistor: Monitors the battery's temperature during charging.
3. Audio Section
Microphones (MIC1 and MIC2): The microphones are connected to the AU_VIN pins via capacitors for coupling. MIC_BIAS pins supply the necessary voltage.
Speaker Connection: The speaker connects to AU_HP_RP and AU_HP_RN pins. These are driven by the audio amplifier section inside the chipset.
4. Touch Sensor and LED Indicators
Touch Controller (BH7133B): Used to detect user touch inputs. Its VCC and OUT pins connect to the GPIO pins of the AB1562A/B/F chipset for input detection.
LEDs: Two LEDs (red and blue) are driven by ISINK0 and ISINK1 pins. They indicate power, charging, and Bluetooth status.
5. RF and Bluetooth Circuitry
Antenna: Connected to the RF_IN pin of the chipset through matching circuits (inductors and capacitors).
Crystal Oscillator: Provides a stable clock signal for Bluetooth operations.
6. External Connections
Charging Connector (Type-C or Micro-USB): Connected to VBUS and GND. It supplies power for battery charging and operating the circuit.
UART Interface: Used for programming or debugging the device.
Working on the Circuit
Power Supply:
When connected to a charger, the charging IC manages power distribution. It charges the battery and powers the system via VSYS.
If no charger is connected, the system runs on battery power through the VBAT pin.
Bluetooth Functionality:
The AB1562A/B/F chipset establishes and manages Bluetooth connections. It uses the RF circuitry for wireless communication.
Audio Processing:
The microphones capture audio signals and send them to the chipset's AU_VIN pins for processing.
The processed audio is output through AU_HP pins to drive the connected speaker.
Touch Input:
The BH7133B touch controller detects user inputs and sends signals to the GPIO pins of the chipset.
LED Indications:
The chipset drives the LEDs to indicate system states, such as pairing, charging, or power-on.
Additional Observations
Component Values: Capacitors (1 µF, 22 µF) and inductors (1 µH) are used for power filtering and signal coupling.
Thermal Management: The NTC resistor protects the battery from overheating.