How to read datasheets
Which correctly describes the "quiescent current (IQ)" of a linear regulator?
- ALeakage current that flows backward from the output pin toward the input pin when the output is turned off
- BThe maximum output current, guaranteed in the datasheet, that the regulator can supply to the load
- CCurrent that flows to ground for the regulator's own operation, separate from the current flowing to the load
Show answer and explanation
Answer: C. Current that flows to ground for the regulator's own operation, separate from the current flowing to the load
Quiescent current is the current consumed by the regulator's internal circuits, such as the voltage reference and error amplifier, so that input current = load current + quiescent current. It ranges from under 1 µA to several mA depending on the product. For example, using a regulator with 50 µA quiescent current in equipment whose standby load current is 10 µA means most of the battery drain goes to the regulator itself. In some products the quiescent current increases with load current, so check the values and graphs at no load and under load.