Explore the TF2925P IC circuit diagram with a comprehensive guide on all pin connections. Download the PDF and enhance your repair skills. Discover the TF2925P Audio Amplifier IC, featuring comprehensive details on output load and all connection components for optimal performance and integration.
1. Pin Functionality and Initial Setup
To correctly integrate the TF2925P, understanding each pin's purpose and electrical requirements is crucial:
Power Pins
VBAT (Pin 1):
➻ Connect to the system's supply voltage.
➻ Use a 1µF decoupling capacitor to suppress power supply noise. Place this capacitor close to the pin to minimize impedance.
➻ Insert a 10Ω resistor in series for further noise filtering and voltage stabilization.
PVDDL (Pin 7) & PVDDR (Pin 22):
➻ These supply the left and right output stages of the audio amplifier, respectively.
➻ Each should have a 1µF decoupling capacitor connected to the ground.
➻ These pins derive their voltage from the boosted output at PVOUT.
AVDD (Pin 8):
➻ Provides power to the internal control circuitry.
➻ Use a 1µF capacitor for decoupling and place a 10Ω resistor between this pin and PVOUT for better isolation.
BVDD (Pin 9):
➻This is an internally generated reference voltage.
➻Connect a 0.1µF capacitor to stabilize this pin.
PVOUT (Pins 19, 20):
This is the boosted voltage output from the internal regulator.
➻Connect to the input of PVDDL, PVDDR, and AVDD pins for the amplifier. Use low-ESR capacitors (e.g., 10µF) to stabilize the output.
Audio Input Pins
INPL (Pin 3) & INNL (Pin 2):
➻ Left-channel audio input. These form a differential pair (non-inverting and inverting).
➻ Typically connect to an audio source or preamplifier circuit. Use AC coupling capacitors (e.g., 0.1µF–1µF) to block DC components from the input.
INPR (Pin 26) & INNR (Pin 27):
➻ Right-channel audio input. Configuration is similar to the left channel.
➻ Apply AC coupling capacitors for signal integrity.
Output Pins
VOPL (Pin 5) & VONL (Pin 6):
Left-channel non-inverting and inverting outputs. These drive the left speaker in a bridge-tied load (BTL) configuration.
VOPR (Pin 24) & VONR (Pin 23):
Right-channel outputs for the right speaker, similarly in a BTL configuration.
PGND (Pins 4, 25):
Power ground for audio output stages. Connect directly to the main ground plane for stable operation.
Control Pins
EN (Pin 14):
Chip enable pin. Pull high (logic 1) to activate the IC. Use a pull-up resistor (e.g., 10kΩ) or connect to the system logic controller.
VKNEE (Pin 11), ALC (Pin 12), SDRIVE (Pin 13):
These are mode and control pins for Automatic Level Control (ALC) and soft-drive features. Pull these pins to VBAT or GND depending on the desired functionality.
2. Boost Regulator Section
The TF2925P integrates a boost regulator to provide a higher voltage for the amplifier stages, ensuring efficient driving of speakers.
LX (Pins 15, 16):
➻ Connects to the inductor (L1) and switching node of the regulator. Use a 10µH inductor capable of handling the expected current.
➻ Place a Schottky diode (e.g., 1N5819) between LX and PVOUT to prevent backflow of current during switching.
PVOUT (Pins 19, 20):
Output of the boost regulator. Use low-ESR capacitors (e.g., 10µF or higher) to stabilize.
PVSNS (Pin 21):
Voltage feedback pin. Connect directly to PVOUT for precise regulation.
PGNDB (Pins 17, 18):
Power ground for the boost regulator. Connect to the main ground plane.
Component Details for the Boost Regulator:
➔ Inductor (L1): 10µH, low DCR, high current rating (2–3A).
➔ Output Capacitor: Low-ESR tantalum or ceramic capacitor, 10–47µF, rated for 10V or more.
➔ Input Capacitor: 10µF ceramic capacitor placed close to VBAT.
➔ Schottky Diode: 1A–3A rating, low forward voltage (e.g., 1N5819).
3. Audio Amplifier Section
The TF2925P features stereo BTL amplifiers for efficient power delivery to speakers.
Speaker Connection:
Connect speakers directly across VOPL/VONL for the left channel and VOPR/VONR for the right channel.
Use 4Ω or 8Ω speakers. Ensure the speaker wattage matches or exceeds the amplifier’s output power rating to avoid distortion or damage.
Output Load:
A typical BTL configuration eliminates the need for output coupling capacitors.
The effective load impedance seen by the amplifier is halved, providing increased power delivery.
Capacitor Recommendations:
Use high-quality ceramic capacitors for decoupling.
Ensure capacitors are rated for at least twice the expected operating voltage.
4. Full Circuit Connection Diagram
Here is a simplified step-by-step outline of the circuit:
Power Supply:
Connect a 5V input supply to VBAT via a 10Ω resistor.
Add a 1µF decoupling capacitor at VBAT, PVDDL, PVDDR, and AVDD.
Boost Regulator:
Place a 10µH inductor between LX and the power supply.
Add a Schottky diode between LX and PVOUT.
Connect 10µF capacitors at PVOUT and PVSNS for stabilization.
Audio Inputs:
Connect audio sources to INPL/INNL and INPR/INNR.
Use AC coupling capacitors (1µF) for signal conditioning.
Audio Outputs:
Connect speakers across VOPL/VONL and VOPR/VONR.
Ensure proper grounding at PGND.
Control Logic:
Tie EN to VBAT through a 10kΩ resistor to enable the IC.
Connect VKNEE, ALC, and SDRIVE to logic levels or control circuits as per the required operation.
5. Testing and Tuning
Once the circuit is complete:
Verify all connections with a multimeter for continuity.
Power up the circuit and check the boosted voltage at PVOUT.
Apply an audio input signal and measure the output waveform with an oscilloscope.
Adjust ALC and SDRIVE settings for desired performance.
6. Troubleshooting Tips
No Boosted Voltage at PVOUT: Check the inductor, Schottky diode, and connections at LX.
Distorted Output: Verify input coupling capacitors and output load impedance.
Overheating: Check for short circuits, incorrect component ratings, or insufficient decoupling.