The maximum current that each Darlington pair can handle is 500mA. However, it's recommended to derate the current to 300mA for reliable operation.
The base current required for each Darlington pair can be calculated using the formula: Ib = Ic / (β1 * β2), where Ib is the base current, Ic is the collector current, β1 is the current gain of the first transistor, and β2 is the current gain of the second transistor.
The maximum voltage that can be applied to the ULN2805A is 50V. However, it's recommended to operate the device within the recommended operating voltage range of 10V to 30V for reliable operation.
To protect the ULN2805A from back-EMF when driving inductive loads, a flyback diode (also known as a freewheeling diode) should be connected in parallel with the inductive load. This diode allows the current to continue flowing in the inductive load when the ULN2805A is turned off, preventing back-EMF from damaging the device.
The maximum operating frequency of the ULN2805A is typically limited by the switching time of the Darlington pairs. The device can operate up to 100kHz, but the actual frequency limit may be lower depending on the specific application and load conditions.
ULN2805A datasheet
by STMicroelectronics
