LED tube lamp

An LED tube lamp comprising:

• an LED module, configured to emit light in response to a driving current;
• and
• a power supply module, electrically connected to the LED module to provide the driving current based on an external driving signal, wherein the power supply module comprises:
• an impedance detection controller, configured to perform, before the LED tube lamp is lighted up, an impedance detection to determine whether the LED tube lamp is electrically connected to a foreign external impedance in series,
• wherein when the LED tube lamp is connected to the foreign external impedance in series, the impedance detection controller causes at least two transient variations to an operating current of the LED tube lamp and limits the operating current of the LED tube lamp to not exceed 5 MIU in root-mean-square (RMS), and
• wherein a duration of each transient variation does not exceed 1 millisecond when the impedance detection controller performs the impedance detection.