Whoop 4.0 Sensor vs Whoop 5.0 / Whoop MG
More: Whoop 5 / MG Review
Whoop 4 and Whoop 5 appear identical from the underside. This article examines whether the Whoop 5.0 sensor is different from the Whoop 4.0 sensor, and, by extension, whether the Whoop MG sensor is merely the same as the Whoop 4.0 with the ECG module attached.
TL;DR – The sensors look unchanged. The visible LEDs are probably identical, but the electronics they attach to and which control them are different. I.e. it’s a different solution.
Here is a technical summary comparing WHOOP models in terms of the known sensor hardware architecture from teardowns and FCC filings, focusing strictly on internal components (not features or app behaviour):
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WHOOP 4.0 vs WHOOP 5.0 – Sensor Architecture
While the exact part number is not publicly disclosed, WHOOP 5.0 features an enhanced photoplethysmography (PPG) sensor that offers:
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- Increased sampling rate (~26 Hz) for more precise tracking of physiological metrics.
- Improved signal clarity and motion artefact rejection.
- Potential use of an updated or different sensor module to support higher data throughput.
The PPG sensor is attached to a printed circuit board, now identified as 820-000100 in FCC filings. This change from Whoop 4.0’s filing suggests a revised PCB to accommodate the enhanced capabilities. Additional components will control and manage the sensor’s power and data. These changes will likely support the increased data processing and power efficiency requirements.
This table combines known and widely speculated information on the components used.
| Aspect | WHOOP 4.0 | WHOOP 5.0 |
|---|---|---|
| PPG Sensor Module | Maxim Integrated MAX86171
(source: TechInsights teardown) |
Unknown exact part number; likely upgraded.
Still a multi-wavelength PPG, but likely featuring a newer Integrated Circuit or enhanced firmware/MCU. |
| LED/Photodiode Configuration | 5 LEDs (3 green, 1 red, 1 IR), 4 photodiodes (PD) | Same physical array layout (5 LEDs, 4 PDs)
Potentially improved optics or signal pathways |
| Sensor Board Part Number | Not disclosed in the FCC | 820-000100 (from FCC ID: 2AJ2X-WS50) |
| Sampling Rate | 1 Hz is typical for passive tracking
Sensor is capable of 4 Hz and 52 Hz for other data. |
26 Hz (claimed by WHOOP for heart rate, motion, and temperature sensing) |
| Implication | Likely used MAX86171 below full capability | Hardware and/or firmware upgraded to enable high-frequency tracking; |
WHOOP 5.0 vs WHOOP MG – Sensor Architecture
Simplistically, Whoop 5.o and MG are internally identical except for the addition of one specific circuit for the ECG feature.
| Aspect | WHOOP 5.0 | WHOOP MG |
|---|---|---|
| Optical Sensor Array | 5 LEDs, 4 photodiodes | Identical to 5.0 |
| Sensor Board Part Number | 820-000100 | 820-000188 (revised PCB to accommodate ECG and additional sensors) |
| ECG Capability | Not present | Yes – via added electrode clasp (hardware-level ECG front end) |
| Temperature Sensor | Internal, improved from 4.0 | Same as 5.0 or further tuned (unclear exact spec) |
| Key Hardware Difference | Enhanced PPG sampling | Adds on-demand ECG, likely with an additional AFE (Analogue Front-End IC) for biopotential capture |
It’s possible that Whoop 5.0 could be entirely identical to Whoop MG, but it’s also limited by software and the lack of an ECG band. Such an approach could reduce production and stock costs.
Notes: WHOOP 4.0
For those wishing to do further research once Whoop 5.0 teardowns become available, here are details for Whoop 4.0 combined from various sources.
- Optical Sensor Module: Utilizes the Maxim Integrated MAX86171, a low-noise analogue front-end (AFE) designed for pulse oximetry and heart rate monitoring. Key features include:
- Dual-channel optical data acquisition system.
- Ultra-low-power operation suitable for wearable devices.
- Supports frame rates from 1fps to 2.9kfps.
- High-resolution 19.5-bit charge integrating ADCs.
- Supports up to four photodiode inputs and nine LED driver outputs.
- Excellent ambient light rejection capabilities.
(Mouser Electronics, Analog Devices)
- Microcontroller: Employs the Maxim Integrated MAX32652, an ultra-low-power microcontroller featuring:
- ARM Cortex-M4 processor with FPU, operating up to 120 MHz.
- 3MB flash memory and 1MB SRAM.
- Multiple low-power modes for energy efficiency.
- Integrated peripherals suitable for wearable applications.
(keil.com, AllDatasheet, Analog Devices)
- Power Management: Incorporates the Maxim Integrated MAX77818, a dual-input, power path, 3A switching mode charger with integrated ModelGauge m5 fuel gauge technology. Features include:
- Smart power path management with dual input support.
- High-efficiency charging with up to 95.6% peak efficiency.
- Integrated low-loss FETs for charging and discharging.
- Accurate battery fuel gauging without the need for calibration.
(Analog Devices, Mouser Electronics, EE Times)
- Temperature Sensor: Uses the Maxim Integrated MAX6631MTT, a digital temperature sensor with:
- 12-bit resolution and SPI interface.
- Operating temperature range from -55°C to +150°C.
- Accuracy of ±1°C over a specified temperature range.
(DigiKey)
Take Out
Whoop 5 features different optical heart rate sensing components, despite appearing unchanged from the outside. There are likely many technical changes, for example, linked to signal processing and power management. Whoop 5 is different from Whoop 4.
It is feasible that Whoop 5.0 and Whoop MG are identical internally and that their feature differences reflect a single software-disabled ECG component and the lack of the ECG band.
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I think you are over exaggerating the changes, there will be minor improvements in hardware as they will be newer versions of the same parts. I’m sure most, not all, will be software release.
This is a common theme to minimise changes to reduce the complexity
depends on how you see it
– let’s say that everything is different other than what can be seen on the outside….that’s a completely new hardware, 100% change, even if only the next version from the same component manufacturer
if you’re talking about what the new bits can do and the incremental improvement in features/capabilities
– that is documented, and i agree it is a modest change.
Another consideration: It is very possible that the circuit board (at a minimum) and (some of) the components change during the production run – and might even be different between different contract manufacturers.
Keep in mind that the Whoop 4.0 was sold for 4 years and Whoop supplied millions of units. It would not be unusual at all for the internals of the device to be changed to allow for lower production costs, for changing of components (e.g. for cost or availability reasons), switching/adding of manufacturing locations, etc.