Tube is used to protect the photodiodes from damage. A safety package containing the photodiodes is provided for their protection. When the photodiodes are reverse-biased, the voltage should never exceed 30V. A photodiode has a pin number of 6. When photodiodes operate, they should not be subjected to temperatures higher than 85°C. It should be noted that the photodiodes should be operated at -25°C as a minimum operating temperature. The current in a photodiode is 2nA even when there is no light input.