KT148A Voice Chip (Serial Version) — MCU Malfunction During Music Playback

1. Problem Description

When using the KT148A serial version voice chip to play music, the microcontroller (MCU) malfunctions immediately. After measurement, it was found that the power supply fluctuates significantly whenever music playback begins. According to the manual, this is likely due to insufficient drive capability, but when the same power supply is connected to your official test board, the MCU works normally.

2. Analysis

The root cause of this issue is quite clear — power supply instability. This is a common problem and can be resolved with basic circuit design practices.

First, note that the KT148A chip has two power supply configurations, as shown in the figure below (pay attention to the power supply notes in the upper-right corner).

Next, the current consumption of the chip depends on two main factors:

  1. Speaker impedance and power rating — the larger the speaker, the higher the current draw.
  2. Playback volume — the higher the volume, the greater the power consumption.
  3. The chip's maximum drive capability is approximately 200 mA.

You can refer to the minimum system schematic of our test board for reference.

3. Solution and Recommendations

The approach to solving this issue is quite straightforward:

  1. Use thicker power traces on your PCB to reduce voltage drop.
  2. Add a decoupling capacitor at the KT148A power input — use an electrolytic capacitor (e.g., 47μF / 16V) or similar.
  3. Keep the KT148A’s power trace as short as possible to reduce resistance and interference.
  4. Ensure a stable and strong power source — avoid using long or thin Dupont jumper wires connected to a weak power supply. Such setups cause severe voltage fluctuations, which can lead to chip resets or abnormal MCU behavior. (This is basic power design knowledge — please review fundamental circuit design principles if needed.)

If you encounter issues downloading voice data, use the official full-featured download board for testing, as shown in the diagram below.

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