Explore the AT2850 audio amplifier circuit diagram, featuring detailed connections and pinout specifications. Download the Datasheet With Wireing PDF.
Sample Devices: Boat Stone 650
Pinout and Pin Names of AT2850
The AT2850 has 20 pins, each serving a specific function. Here is the detailed breakdown:
LINN (Pin 1) - Left Channel Negative Input
Connects to the negative terminal of the left audio source input through a capacitor (0.47 µF) and a resistor (10 kΩ).
LINP (Pin 2) - Left Channel Positive Input
Connects to the positive terminal of the left audio source input with the same capacitor and resistor setup as LINN.
EN (Pin 3) - Enable Pin
Connected to the control system, enabling or disabling the amplifier. A high logic level turns on the amplifier.
MODE (Pin 4) - Mode Selection
Allows the user to switch between different operational modes (e.g., power-saving or normal modes).
BYP (Pin 5) - Bypass Capacitor
Connected to a capacitor (1 µF) to stabilize the internal bias voltage.
AGND (Pin 6) - Analog Ground
Common ground for the analogue section of the amplifier. Connect this to the power supply's ground.
AVDD (Pin 7) - Analog Voltage Supply
Provides power for the analogue circuitry, connected through decoupling capacitors for noise filtering.
CVDD (Pin 8) - Core Voltage Supply
Powers the core section of the IC, typically connected to VDD through bypass capacitors.
CP1 (Pin 9) - Charge Pump 1
Part of the charge pump circuit. Connect to a capacitor (4.7 µF) for boosting voltage.
CN1 (Pin 10) - Charge Pump Negative 1
Complements CP1. Connect to the same capacitor as CP1.
CN2 (Pin 11) - Charge Pump Negative 2
Connects to another capacitor (4.7 µF), similar to CP1 and CN1.
CP2 (Pin 12) - Charge Pump 2
Works with CN2 for voltage boosting.
CGND (Pin 13) - Charge Pump Ground
Provides grounding for the charge pump section.
PVOUT (Pin 14) - Power Output
Supplies power for driving the load (e.g., speakers). This pin connects to a set of filtering capacitors (1 µF, 10 µF, 470 µF) for stabilization.
PVDD (Pin 15) - Power Supply for Output Stage
The main power source for the amplifier's output stage is Decoupling capacitors are connected for smooth power delivery.
VON (Pin 16) - Output Negative Terminal
Connected to the speaker's negative terminal.
VOP (Pin 17) - Output Positive Terminal
Connected to the speaker's positive terminal.
PGND (Pin 18) - Power Ground
Ground reference for the power stage.
ALC (Pin 19) - Automatic Level Control
Adjusts the audio signal automatically to prevent distortion.
BS (Pin 20) - Bootstrap Pin
A bootstrap capacitor connects here to enhance output drive strength.
Step-by-Step Connection Guide
1. Audio Input (Pins 1 & 2 - LINN, LINP)
Connect the left audio source's positive terminal to LINP (Pin 2) through a 0.47 µF capacitor and a 10 kΩ resistor in series.
Similarly, connect the negative terminal to LINN (Pin 1) using identical components.
2. Control System (Pins 3 & 4 - EN, MODE)
Connect the EN (Pin 3) to the control system's output pin to enable/disable the amplifier.
Use MODE (Pin 4) to toggle between power-saving and operational modes. This pin can be connected to a microcontroller or manually controlled.
3. Power Supply and Bypass Capacitor (Pins 7 & 5 - AVDD, BYP)
Connect AVDD (Pin 7) to the power supply through decoupling capacitors (e.g., 10 µF and 0.47 µF) for noise reduction.
Place a 1 µF capacitor on BYP (Pin 5) to stabilize the internal voltage.
4. Charge Pump Circuit (Pins 9-12 - CP1, CN1, CP2, CN2)
Connect CP1 (Pin 9) and CN1 (Pin 10) to a 4.7 µF capacitor.
Similarly, connect CP2 (Pin 12) and CN2 (Pin 11) to another 4.7 µF capacitor. These capacitors enable the internal charge pump to boost voltage levels.
5. Power Grounding (Pins 6, 13, & 18 - AGND, CGND, PGND)
Connect AGND (Pin 6) to the analogue ground, CGND (Pin 13) to the charge pump ground, and PGND (Pin 18) to the power stage ground. These grounds ensure stable operation by separating noise-sensitive areas.
6. Speaker Connection (Pins 16 & 17 - VON, VOP)
Connect VON (Pin 16) to the speaker's negative terminal.
Connect VOP (Pin 17) to the speaker's positive terminal.
Ensure the speaker impedance matches the amplifier’s specifications to prevent damage.
7. Automatic Level Control (Pin 19 - ALC)
Use the ALC (Pin 19) pin to connect an automatic level adjustment circuit if needed. This pin automatically adjusts the audio levels to prevent distortion.
8. Output Power Filtering (Pin 14 - PVOUT)
Connect a set of capacitors (1 µF, 10 µF, and 470 µF) between PVOUT (Pin 14) and ground to stabilize the output power and minimize noise.
9. Bootstrap Capacitor (Pin 20 - BS)
Connect a bootstrap capacitor (usually 0.1 µF) to BS (Pin 20). This capacitor enhances the output drive and efficiency of the amplifier.
Working of AT2850 Amplifier
Audio Input:
The audio signal enters through LINN and LINP pins. The differential input stage ensures noise reduction and amplifies the signal with minimal distortion.
Power Amplification:
The amplifier boosts the input signal's strength, powered by AVDD and PVDD. Internal circuits ensure efficient power usage and high-quality audio output.
Charge Pump:
The charge pump circuit, connected through CP1, CP2, CN1, and CN2, boosts the voltage internally, enabling the amplifier to drive low-impedance speakers effectively.
Output Drive:
The amplified signal is sent to the speaker through VON and VOP. The bootstrap capacitor at BS enhances this process, allowing better performance at high volumes.
Control Features:
The EN pin enables or disables the amplifier, while MODE allows switching between normal and power-saving modes. The ALC pin ensures the output remains distortion-free by dynamically adjusting the signal level.
Applications of AT2850 Amplifier
Portable Speakers: Efficient for small, battery-operated speakers due to its power-saving features and high-quality output.
Bluetooth Audio Devices: Can be integrated with Bluetooth modules to amplify wireless audio signals.
TVs and Monitors: Used in built-in speaker systems to enhance audio quality.