Fingerprint Scanners on Smartphones: How Much Power Do They Really Consume?

The power consumption of a fingerprint scanner on a smartphone is often a topic of interest for both users and developers. While some may assume that such a sensor draws a significant amount of power, the reality is quite different. In this article, we will explore the actual power usage of these scanners and place it in the context of a smartphone's overall power consumption.

Overview of Fingerprint Scanner Power Consumption

Typically, fingerprint scanners consume around 10 to 50 milliwatts (mW) during operation, depending on the technology used (capacitive, optical, or ultrasonic) and the specific design of the device. One key factor to consider is that while the scanner does use more power during the scanning process, it is usually inactive most of the time. This helps to keep overall energy consumption relatively low.

Comparison with Other Smartphone Components

When comparing the power consumption of a fingerprint scanner with other components in a smartphone, it becomes clearer why it is considered to be a low-power component. For instance:

Wi-Fi: 300mA peak current Display: 100–400mA continuous Bluetooth Low Energy: 15mA continuous Fingerprint Scanner: 150mA peak current and 120mA when reading (mentioned in a datasheet)

Modern sensors have even greater efficiency. A sensor used in Point of Sale terminals consumes only 20μA in operating mode and 20μA in stand-by mode, making it comparable to a mechanical button when it is off and a notification LED when it is effectively reading a fingerprint.

Activation and Standby Mechanisms

The fingerprint scanner is not always active but is only triggered when the phone is expecting authentication. This means that the scanner is inactive most of the time. Additionally, some phone brands incorporate feedback mechanisms such as vibrations, LED blinking, or screen lighting when a successful fingerprint read is achieved or when the read fails. However, it's important to note that these additional mechanisms can consume more current than the sensor itself.

Compromise Between Security and Convenience

Fingerprint scanners on smartphones strike a balance between security and convenience. A fingerprint sensor with a 99.999% true positive rate requires a full second to read, whereas most sensors boast a 0.1-second recognition time. This makes smartphone fingerprint sensors less suitable for security-critical applications but still a significant improvement over traditional swipe patterns or pin codes.

While the power consumption of these sensors is low, they do play a crucial role in enhancing user experience and security. Modern advancements in technology ensure that these sensors consume minimal power, making them an integral part of modern smartphones without significantly impacting battery life.

In conclusion, the power consumption of a fingerprint scanner on a smartphone is negligible compared to other components, making it a low-energy sensor that offers a convenient and secure alternative to traditional authentication methods.