Will The Fitbit Charge 5 Outshine The Fitbit Luxe?

We don’t know, and we do not comment on whether one device is better than its previous generation. What we do is look at and compare generations of devices. And while we wait for our pre-order of our Fitbit Charge 5 to arrive, we will take a look at what Fitbit Luxe has inside of it.

Fig. 1: Fitbit Luxe.

Fig. 2: Fitbit Inspire 2.

The Luxe has other changes from the Inspire 2, including the AMOLED display, and a haptic assembly more similar to the Taptic Engines found in the Apple Watch and Apple iPhones.

Fig. 3: Fitbit Luxe Haptic Driver.

Fig. 4: Fitbit Luxe Haptic Driver.

Fig. 5: Taptic Engine, Apple iPhone 12 mini.

What the Fitbit Luxe looks like from a teardown point of view

It is unnecessary to do a teardown on a Luxe to see its rear sensors are different from that of the Fitbit Inspire 2, but we did. The specifications on the Luxe state it has a few sensors more than the Inspire 2.

Fig. 6: Fitbit Luxe Sensors.

Wearables, especially fitness trackers such as the Luxe and the Fitbit Inspire 2, can have many helpful health features such as heart rate monitoring, skin temperature sensors, and SpO2 sensors. A single MCU controls most, if not all, of these sensors. Fitbit had used Infineon (Cypress Semiconductor) PSOC controllers in many of their past fitness bands, but here in the Fitbit Luxe, we found Infineon replaced by the latest Ambiq ARM Cortex-M4.

Ambiq Apollo4 Blue eMRAM provides a very large, efficient, non-volatile memory

However, this new Ambiq Apollo4 Blue is not just another ARM Cortex-M4 SoC. Instead, the Apollo4 Blue has embedded MRAM, or eMRAM and is our first such IC to add to our library. The TechInsights memory experts have started three separate analyses, and our subscribers can now see the preliminary images today and stay up-to-date as the reports progress.

Fig. 7: Fitbit Luxe Board Shot.

Fig. 8: Ambiq Apollo4 Blue MCU package.

Comparing the package sizes of the Infineon PSOC 6 used in the Inspire 2 and the Ambiq Apollo4 Blue used in the Luxe, the Infineon is a two die package, but the second die is the Bluetooth Front-end die. The Infineon MCU has a package with 104 pins and an area of 19.2 mm2. The Ambiq Apollo4 Blue is also a multi-die IC. However, it has 131 pins and a larger package area of 22.1 mm2.

Fig. 9: A 16Mb eMRAM array module with TSMC 22ULL process on Ambiq Apollo4 Blue MCU die.

We are still in the process of completing the full Deep Dive Teardown of the Fitbit Luxe, but we expect to find this new Apollo4 Blue SoC controls all sensors and Bluetooth functions. Stay tuned.