In a UV Sensor Application design, do I need to add a layer of glass surface protection? Will the transmittance of the glass affect the accuracy of the Si1132? How can this be avoided?
The Si1132 can use any overlay material that has even transmissivness in visible and IR wavelengths. A linear scaling of results is used based on the percentage of UV/IR wavelengths transmitted by the overlay.
What is the detection distance of the proximity sensor?
A long range proximity design can detect from 1 to 2 meters indooors. A narrow half angle LED should be used with high power, and lensing may be necessary above the sensor. The Si1142, Si1143, Si1146, Si1147, and Si1153 can combine 2 LED drivers for up to 500mA drive of the IR LED.
Does the Si114x gesture sensor also allow simultanious UV sensing and proximity/gesture?
Or at least switching between the two?
You can do both UV Index sensing and proximity/gestures in one design.
UV index sensing requires long sample periods that limit the maximum frequency at which samples can be taken. The system can simultaneously do both UV index sensing and simple proximity functions that do not require high sample rates.
For systems wanting to do UV Index and gestures with the same sensor, the sensor functions would need to multiplex as gesture require a faster sample rate than what can be provided while UV Index is enabled.
Si70xx maintains its accuracy over a wider range of temperature and RH compared to Sensirion. In addition Si70xx has lower long-term accuracy drift and supports an optional protective cover. The pin-out of the Si70xx 3x3 QFN package is drop-in compatible. The registers and command set are software compatible. This allows the device to be a 2nd source to other existing solutions in the market.
Silicon Labs hosted a set of webinars to introduce and educate engineers on products that are ideal for designs that fall within the Internet of Things. The 1K+ attendees asked great questions to better understand the solutions. We have posted the answers to help everyone in our community considering a new IoT application. One of these questions may help you.
You can review the questions filtered on the following categories or choose to view them all:
Can I use a capacitive sensing-enabled Silicon Labs MCU for proximity sensing?
Proximity sensing with the Silicon Labs CS0 capacitive sensing block is possible. Proximity sensing requires careful hardware and firmware design. Maximum range of a sensor will depend on response time and sensor characteristics.
Hardware considerations: A sensor’s surface area is proportional to sensitivity. Design the sensor or multiple sensors that can cover as much of the sensing surface as possible.
Place the sensor as close to the sensing surface as possible. Designing a flex board that can be placed directly beneath the sensing surface in a product will help increase sensitivity. A flex board can route the sensor to the MCU through a flex cable connector.
If possible, isolate the sensor from the MCU’s ground return path. Proximity to ground will reduce maximum range seen by the sensor.
Firmware considerations: Accumulate samples in firmware instead of using the hardware-implemented accumulation feature. The hardware accumulator in the CS0 block auto-divides accumulated samples back down to a 16-bit value, effectively right-shifting the sample and discarding the accumulated LSBs. Losing the LSBs will limit the range of the sensor.
Accumulate as many samples as possible without effecting the required response time of the sensor.
Use a debounce algorithm to determine whether a candidate proximity event persists across multiple samples. If using a Silicon Labs MCU that includes the channel binding feature, bind multiple sensor-connected CS0 inputs together to yield a single sensor with a larger surface area.
A: No, a reset period of at least 150 ns is required to propertly reset the internal integrating capacitor. To guarantee accuracy, no current must flow between the IIN and IOUT pins while the current sensor is in reset. Failure to do this will result in offset errors.
Q: Surge testing: what testing have we done with the Si8503 and at what specific levels and rise/fall time durations? Is this our Vtr of 8KV peak for 10 sec? They need to pass IEC 61000-4-5 – surge immunity test (combination wave) – 6 KV/ 3 KA at 1.5/20uS, 8/20uS voltage/current surge waveform.
A: The Vtr 8kV is a 10 sec dc test, and has nothing to do with surge testing. The Si8503 passes more than 10 kV (i.e. 1.2us/50us). All the above tests will pass their requirements with more than a 2x margin.