SICK AG: Shrinking the Size of Precise Optical Sensors with a µSLIC Power Module

SICK AG, based in Waldkirch, Germany, is a leader in the design and manufacturing of industrial sensor-based solutions. SICK sensors are used worldwide in factory, process, and logistic automation solutions, providing the foundation for controlling processes securely and efficiently, protecting people from accidents, and preventing environmental damage. Founded in 1946, the company has more than 10,000 employees worldwide, as well as more than 50 subsidiaries and equity investments.


  • Shrink the size of its optical proximity switch by more than 10% while increasing its performance



  • Met stringent power and performance requirements
  • Exceeded tightest PCB space requirements
  • Reduced BOM/PCB due to higher integration and fewer external discretes

Bohli Alexander

“Using Maxim’s MAXM15462 ultra-small power module and the tiny MAX14827A IO-Link device transceiver, we were able to achieve the design of one of the tiniest PCBs by meeting our very tough power consumption requirements due to the high efficiency of the power module and the low RON of the IO-Link PHY.”

- Alexander Bohli, Senior Engineer R&D Electronics, SICK AG


SICK has developed one of the world’s smallest time-of-flight (ToF) optical switches. Available in a tiny 17mm x 42mm outer-case using a PCB of just 8mm x 27.8mm, the switch delivers precise measurement, covering a range of up to 1300mm. Alexander Bohli, one of the company’s senior engineers in electronics development of optical sensors, is an expert in miniature ToF sensors. To provide SICK’s customers with even smaller and more precise solutions, Bohli and his team faced the challenge of creating the new switch by shrinking an existing optical ToF sensor by more than 10%. This reduction in size would help customers reduce the space and associated costs needed for implementation in their production lines.

To accomplish these goals, the team needed underlying ICs which would fit on an even smaller PCB, inside the case, while also supporting increased requirements related to accuracy, power loss, and higher intelligence of the sensor.

SICK and Maxim enjoy a long-standing business relationship, but for the company’s industrial, fan-less sensor designs, it is mandatory to find the best and most efficient solution for each application. This meant that for SICK’s new design of the WTT4, part of the PowerProx family, the engineers had to make the chassis so tiny that it can be mounted closely to end customers’ equipment. At the same time, they needed to ensure the new WTT4 design could provide a signal range from 50mm to 800mm (at 1kHz) using a laser diode Class 1.

“Concerning the design of industrial sensors, size and power consumption are always a big challenge—especially when designing high-performance miniature sensors,” noted Bohli. “Applications, for example, in the packing industry are getting more and more complex, even more so with Industry 4.0. There are market demands for ultra-small sensors which can be integrated and configured via IO-Link. Further, thanks to the increased computing power compared to existing miniature time-of-flight switches, the customer can configure significant parameters of the measuring system, such as averaging filters, switching hysteresis, or timings.”

Solution and Benefits

The company addressed its challenges with Maxim Integrated’s MAXM15462 42VIN Himalaya™ µSLIC step-down power module, which delivers 300mA in a tiny 2.6mm x 3mm package. Also for its new WTT4, SICK is using the MAX14827A IO-Link device transceiver, which features two ultra-low-power drivers with active reverse-polarity protection and is available in a 2.5mm x 2.5mm WLP.

“A typical switching regulator requires an inductor which normally is much bigger than the regulator itself. Furthermore, the solution with a discrete inductor requires complex dimensioning, suffers from losses introduced by the PCB layout, and causes electromagnetic interference. Integrated modules like the µSLIC devices provide the perfect solution, not only in the PCB area, but also in terms of perfect matching between the regulator and the inductor, resulting in much better efficiency and EMI performance,” explained Bohli.

Bohli and his team evaluated various solutions before going with Maxim, finding the devices to provide the sweet spot in terms of performance, miniaturization, and total cost. “By using the MAXM15462, which already includes the inductor, in combination with the MAX14827A IO-Link transceiver, we were able to dramatically reduce the board space of the whole input circuitry and, thus, were able to achieve our goal of reducing the total size of the sensor,” he explained.

Designing the MAXM15462 into its new WTT4, SICK is experiencing about 90% efficiency and reduced PCB area and height, which wouldn’t be possible using discrete inductors. The design process was also shorter, as no dimensioning of the regulator and subsequent qualification were needed.

“With the design of our brand-new WTT4, we offer the world's smallest optical ToF-based proximity switch,” said Bohli. “Based on the support we’ve received from the Maxim team, we will of course see how we can work together in upcoming designs. As I’ve noted, going smaller with higher integration and lower power consumption are key.”

SICK AG has designed a highly flexible programmable optical sensor in one of the smallest form factors, which contains a MAXM15462 300mA power module with integrated inductor, and a MAX14827A IO-Link Phy Photo Courtesy of SICK AG SICK AG has designed a highly flexible programmable optical sensor in one of the smallest form factors, which contains a MAXM15462 300mA power module with integrated inductor, and a MAX14827A IO-Link Phy. Photo: Courtesy of SICK AG