LM3900D datasheet by Texas Instruments

LM3900D Frequently Asked Questions (FAQs)

• What is the maximum input voltage that can be applied to the LM3900D?
  The maximum input voltage that can be applied to the LM3900D is 40V, but it's recommended to keep it below 35V for reliable operation.
• How do I ensure the LM3900D operates within its safe operating area (SOA)?
  To ensure the LM3900D operates within its SOA, keep the input voltage below 35V, output current below 1A, and junction temperature below 125°C. Also, ensure the device is properly heatsinked and the PCB is designed to minimize thermal resistance.
• What is the purpose of the capacitor between pins 1 and 16?
  The capacitor between pins 1 and 16 is a decoupling capacitor that helps to filter out noise and ripple on the input voltage. A 0.1uF to 1uF ceramic capacitor is recommended.
• Can I use the LM3900D as a voltage regulator?
  While the LM3900D can be used as a voltage regulator, it's not its primary function. The device is designed as a voltage converter, and its output voltage is not tightly regulated. If you need a regulated output, consider using a dedicated voltage regulator IC.
• How do I calculate the output voltage of the LM3900D?
  The output voltage of the LM3900D is determined by the ratio of the resistors R1 and R2, connected between pins 5 and 6. The output voltage is approximately equal to the input voltage multiplied by the ratio of R1 to R2.