Industry news--Karmin Electronic (HK) Limited

St released a number of new MEMS sensors, breaking through the performance power ratio and unlocking a new field of wearable applications
2022-07-25

We also released the first dual full-scale pressure sensors: lps22df and lps28dfw, with power consumption as low as 1.7 µ A and absolute accuracy of 0.5 HPA; The power consumption of the three-axis accelerometer lis2du12 is only 0.45 µ a.

LSM6DSV16X

Portable devices call for more efficient inertial sensors

Although the image quality of mobile camera is constantly improving, manufacturers still face challenges in image stability. Many people use software to improve the overall clarity, but still can not achieve the effect of physical image stabilizer. In the mobile camera scene, the inertial MEMS senses the movement of the camera, and the image sensor moves in the opposite direction to compensate. However, the tight shell and energy consumption limitation of smart phones will bring challenges to the use of inertial MEMS. AR and VR headsets also require more efficient sensors. Accuracy is critical in tracking head or hand movements. Accurate and fast sensors can provide a more realistic experience and even alleviate VR motion sickness. However, as most of these devices are powered by batteries, the requirements for energy consumption are becoming higher and higher.

Engineers have encountered practical difficulties in designing high-energy inertial sensors. To improve performance, engineers will try to use filters and other mechanisms to reduce the signal-to-noise ratio, but this also increases power consumption. Engineers need to make a choice between stability and battery life. In addition, because MEMS must be packaged in small packages, engineers cannot improve the accuracy of MEMS by increasing its size.

The low power consumption mode only consumes 0.65 malsm6dsv16x, which solves this problem with the help of the new spring design in its mechanical structure. In addition, STMicroelectronics adjusts the gain of the amplifier to improve performance while maintaining low power consumption. Therefore, lsm6dsv16x consumes only 0.65 MA in high-performance mode (total power consumption of gyroscope and accelerometer), compared with 1.2 MA in lsm6dsrx, although these two devices have similar noise levels in low-power mode. Engineers who develop optical image stabilizers for smart phones no longer need to face the contradiction between performance and power consumption. In contrast, competitors' devices consume at least twice as much power in low-power mode as STMicroelectronics.

The running speed of MLC is increased by 2 times, and adaptive configuration (ASC) is supported

Machine learning kernel (MLC) is another feature that helps save energy. With the help of the decision tree to run the information of the sensor, there is no need to wake up the microcontroller, which significantly reduces the total power consumption. The running speed of MLC in lsm6dsv16x is twice that of previous products, and the output data rate (ODR) is increased to 100 Hz ~ 240 Hz. Therefore, engineers can process more data and save more energy in a given time.

Users can also use 16 finite state machines (FSM) to identify specific patterns. In addition, this new device supports adaptive configuration, enabling the FSM to reconfigure itself without waking up the MCU. Developers can program various conditions and environments that will trigger reconfiguration for greater flexibility. Finally, both MLC and FSM can notify each other to realize smarter applications and track physical activities more accurately, such as detecting whether smart phones are placed downward.

QVAR opens the door to new applications such as population statistics

Lsm6dsv16x introduces QVAR into lsm6 series MEMS inertial sensors. Engineers only need to connect two electrodes to measure the change of ambient electrostatic charge, and enable this function by changing two registers. QVAR opens the door to new applications such as population statistics. Instead of using LEDs and photodiodes, engineers can place electrodes on the wall to measure whether someone is approaching. We have also written corresponding application notes to help designers develop demonstration models. In addition, STMicroelectronics will provide more use cases before the end of the year. Lsm6dsv16x is compatible with other member pins of lsm6ds series through the pin sharing mechanism between QVAR and test pins.

Lps22df and lps28dfw

With the wide application of wearable devices, the activity tracking function has become a standard configuration, and the pressure sensor must adapt to a wider range of physical scenes. From mountain climbing to swimming, sensors must be able to reliably track users and provide accurate information about their physical activities. The challenge is that climbing mountains or stairs is completely different from swimming in the pool, because water brings different pressures. For example, the pressure of 14.5 psi will be applied when diving into 10 meters deep water, which is the same as the atmospheric pressure at sea level. Therefore, the pressure sensor must consider different physical conditions without excessive power consumption.

Only 9.1 µ A and 7 µ a are consumed in high-performance mode

The first pressure sensors lps22df and lps28dfw that support dual full-scale can help solve this problem. They can detect whether the user is on or under the water, and switch to the corresponding range. The lps22df supports a maximum pressure of 1260 HPA, while the lps28dfw supports a pressure of up to 4000 HPA, and their consumption in high-performance mode is 9.1 µ A and 7 µ a respectively. In contrast, lps22hb consumes 12 µ a at a maximum pressure of 1260 HPA.

LIS2DU12

Lis2du12 achieves a new balance between performance and energy consumption. Equipped with a new LC filter and anti aliasing filter, this product is more accurate than the previous generation. LC filter can filter electrical noise and anti aliasing filter can prevent sampling error. Both of them can greatly improve signal quality without significantly increasing power consumption. The previous generation of lis2dw12 consumes only 380 Na in low-power mode, while the more accurate new lis2du12 consumes only 450 Na. In contrast, the power consumption of competitors' products tends to hover around 1 µ a.

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