In modern electronic equipment, audio power amplifier plays a crucial role. The CST8110 chip from ChipSourceTek is a high-performance audio power amplifier designed for low electromagnetic interference (EMI) applications. The chip does not require an external filter and supports class AB/D switching mode of operation, making it excellent in portable audio products.

1, turn off current (<1uA)

    Turn-off current refers to the current consumption of the equipment in the non-working state. ChipSourceTek - CST8110 chip in off mode of current consumption is extremely low, less than 1 microamps (1) including A, this helps to prolong the life of batteries, especially suitable for portable devices such as bluetooth speakers and intelligent speakers, etc. These devices need to be standby for a long time, so the low power characteristics are particularly important.

2, OCP, OTP, UVLO protection function

   ChipSourceTek-CST8110 integrates a number of protection features to ensure its stability and security:

1.     Overcurrent Protection (OCP)：When the output current exceeds the set value, the chip automatically reduces the output current to prevent damage. This is important to protect speakers and other loaded devices.

2.     Overtemperature Protection (OTP)：When the chip temperature is too high, the overtemperature protection function will start and reduce the output power or shut down the output to avoid overheating damage to the chip. This feature is especially important for high-power amplifiers that operate for long periods of time.

3.     Undervoltage Shutdown (UVLO)：When the power supply voltage falls below a set threshold, the UVLO function automatically turns off the output to prevent performance degradation or damage due to undervoltage. This is critical to ensure the stability of the system in unstable power supply environments.

3. Scope of application

    ChipSourceTek-CST8110 is used in a wide range of audio devices, including:

•     Pull rod speaker：Strong portability, suitable for outdoor activities.

•     Backpack speaker：Lightweight design, suitable for travel.

•     Bluetooth speaker：Wireless connection, easy to use.

•     Smart speaker：Integrate multiple intelligent functions to meet diverse needs.

•     megaphone：Suitable for public places, providing high-power audio output.

•     High power Bluetooth speaker, sound bully：Provides powerful sound effects for music lovers.

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4. Block diagram and pin description

    A block diagram of the ChipSourceTek-CST8110 shows its internal structure and workflow. The main modules include input stage, amplifier stage, output stage and protection circuit. Each module works together to ensure efficient amplification and transmission of audio signals.

    Pin specification

•     Ci (Straight capacitance)：A capacitor of 0.1µF or less further eliminates clatter-pitting and noise coupled in from the input.

•     Cs (Power decoupling capacitance)：It is recommended to use a low ESR (equivalent series resistance) capacitor less than 1µF, when VDD=12V, to better filter out low-frequency noise, add a low ESR chip capacitor (not less than 10µF). The decoupling capacitor should be as close to the VDD pin as possible, preferably kept within 1.5mm.

•     CTRL pin：Control the power amplifier on and off, and configure the power amplifier to work in Class D or Class AB mode through level Settings. The level of the pin can be controlled by an external divider resistor. Practical applications usually combine two GPIO ports and a resistance network. For example, the level values of the SD and AB/D ports can be set to "H" (VIO) or "L" (GND) via the GPIO interface.
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5, PCB design precautions

    When designing a PCB, you need to consider the following to optimize the performance of the ChipSourceTek-CST8110:

1.     Position of the power supply decoupling capacitor：Place it as close to the ground pin of the power supply as possible, and reserve appropriate positions for different noise sources and interference sources.

2.     Layout of the output current loop：Minimize the loop area, whether it is a magnetic bead or a filter composed of inductors and capacitors, should be as close as possible to the output pin. This part of the circuit should be away from sensitive signal lines (such as audio input signal lines) and other circuits.

3.     Routing optimization：Ground and power cables should be as short and wide as possible to reduce resistance and inductance.

4.     Heat dissipation treatment：The heat sink should be reasonably welded in the heat dissipation area of the PCB board, and the area near the chip should be covered with copper foil to strengthen heat dissipation.

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6. Electromagnetic compatibility design

    Electromagnetic compatibility (EMC) is an important aspect of modern electronic equipment design that cannot be ignored. In order to achieve good EMC results, you need to pay attention to the following aspects:

1.     Power filter：Most EMC requirements can be met with a magnetic bead filter, but it should be noted that the switching edge of a Class D amplifier changes very quickly.

2.     Ground design：Reasonable ground wire layout can significantly reduce electromagnetic interference. The ground cable should be as short and wide as possible to form a complete grounding plane.

3.     Shielding measure：Add a shield to sensitive areas or use a shield to prevent external interference from entering the device.

4.     Component selection：Select capacitors and resistors with low ESR and high frequency characteristics to reduce unnecessary electromagnetic radiation.

5.     Wiring strategy：Avoid parallel wiring, especially high-speed signal lines and power lines, to reduce mutual inductance and crosstalk.

    The ChipSourceTek-CST8110 is a powerful and flexible audio power amplifier suitable for a variety of application scenarios. Through reasonable design and optimization, it can give full play to its performance advantages and provide users with high-quality audio experience.