The current consumed by an IC's own internal circuitry, such as a regulator's, separate from the current delivered to the load; written IQ. It dominates standby consumption in battery-powered equipment and ranges from under 1 µA to several mA depending on the product.
Japanese name: 静止電流
Quiescent current appears in 2 practice questions across 2 topics, including How to read datasheets, Power Management.
Field: How to read datasheets
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.
Answer: C. About 56%
A linear regulator passes the same current at input and output and maintains the output voltage by dissipating the voltage difference as heat in a transistor. Efficiency is therefore roughly output voltage ÷ input voltage: 1.0 ÷ 1.8 ≈ 56%, with the remaining 44% turned into heat. It suits small input-output differences or noise-sensitive loads; for large differences, a switching regulator usually steps the voltage down first.
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.
Which correctly describes the "quiescent current (IQ)" of a…As an Amazon Associate I earn from qualifying purchases.
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