LM1877MX-9/NOPB datasheet by Texas Instruments

LM1877MX-9/NOPB Frequently Asked Questions (FAQs)

• What is the recommended PCB layout for optimal performance of the LM1877?
  A good PCB layout for the LM1877 involves keeping the input and output traces short and separate, using a star-ground configuration, and placing the decoupling capacitors close to the IC. A 4-layer PCB with a dedicated ground plane is recommended.
• How do I choose the right gain resistors for my application?
  The gain resistors (Rf and Ri) should be chosen based on the desired gain and input impedance. A higher gain requires smaller resistors, while a higher input impedance requires larger resistors. The datasheet provides a gain calculation formula to help with the selection.
• What is the maximum power dissipation of the LM1877?
  The maximum power dissipation of the LM1877 is 2.5W. However, this can be increased by using a heat sink or a thermally enhanced package. The power dissipation should be calculated based on the output power, supply voltage, and quiescent current.
• Can I use the LM1877 as a line driver?
  Yes, the LM1877 can be used as a line driver. However, it's essential to ensure that the output stage is properly terminated to avoid oscillations. A 100-ohm to 150-ohm load impedance is recommended, and the output should be AC-coupled to the load.
• How do I reduce noise and hum in my LM1877-based circuit?
  To reduce noise and hum, use a well-regulated power supply, decouple the power pins with 10uF to 22uF capacitors, and use a star-ground configuration. Additionally, keep the input and output traces separate, and avoid running digital and analog traces parallel to each other.