Why only 5k resistors are used in 555 timer?

5kΩ resistors are commonly used in 555 timer circuits to balance the trade-off between power consumption and response time. This value provides a suitable charging and discharging time for the timing capacitor, allowing for a wide range of timing intervals while maintaining stability and efficiency. Additionally, 5kΩ is a standard resistor value that is readily available, making it convenient for designers.