Ruigu Electronic

January 20, 2025, Tienen, Belgium — Global microelectronics engineering company Melexis announced the launch of the MLX90617 non-contact infrared temperature sensor chip, designed specifically for induction cookers. The chip employs innovative optical filtering technology to penetrate the ceramic panel of the induction cooktop and accurately measure the temperature at the bottom of the cooking vessel. This breakthrough technology significantly enhances the precision of cooking control, improves the safety of induction cooktop use, and greatly enhances the overall user experience.

Due to limitations of existing technology, traditional induction cooktops primarily rely on temperature monitoring from the back of the ceramic glass panel for temperature control, which to some extent affects the precision of temperature control. To overcome this limitation, Melexis has successfully developed an advanced and cost-effective MLX90617 solution that can penetrate the ceramic glass panel of induction cooktops and accurately measure the temperature at the bottom of the cooking vessel in real time.

Principle

The MLX90617 employs precise optical filtering technology optimized for induction cooker ceramic glass plates. This technology accurately captures infrared radiation originating from the bottom of the cooking vessel that penetrates the ceramic glass plate, and effectively filters out infrared interference emitted by the ceramic glass plate itself through advanced algorithms, ensuring the accuracy and reliability of temperature measurements.

Operating Mode

The MLX90617 is designed to work in conjunction with another non-contact temperature sensor chip (such as the MLX90614 or MLX90632), both of which are installed beneath the ceramic surface of the induction cooktop. Additionally, optional LED and light sensor chips can be added to enable in-situ emissivity measurement, further enhancing measurement accuracy.

To precisely measure the temperature of the cooking vessel, the MLX90617 primarily measures the radiation emitted from the bottom of the cooking vessel, while the other sensor chip monitors the radiation generated by the ceramic glass plate and the sensor itself. The integrated LED and light sensor chip are used to measure the reflectance of the cooking vessel, thereby calculating its emissivity. Through efficient real-time processing algorithms, the system can accurately calculate the temperature at the bottom of the cooking vessel while effectively eliminating interference from the ceramic surface and the sensor chip itself.

Compared to the traditional method of measuring the temperature of the ceramic glass (Tglass) used in conventional induction cookers, the MLX90617 employs advanced optical filtering technology to penetrate the glass in real time and directly measure the temperature at the bottom of the cooking vessel (Tpot). Comparison results show that the measurement results provided by the MLX90617 are significantly closer to the actual temperature of the cooking vessel, fully demonstrating its exceptional temperature measurement accuracy.

Improving Induction Cooker Design

Induction cooker manufacturers can integrate the MLX90617 chip from Melex to create an advanced solution that significantly enhances product accuracy and optimizes the cooking experience for end users.

This sensor chip directly monitors the temperature at the bottom of the cooking vessel rather than the glass surface temperature, enabling the induction cooktop’s electronic control system to more precisely control food temperature. This feature is particularly advantageous for cooking operations requiring precise temperature adjustments within a narrow range. Additionally, the chip features temperature overlimit detection functionality, enhancing system safety and driving the development of more advanced automatic cooking systems.

The MLX90617 chip has a factory-preset wide operating temperature range (0°C to 125°C) and is specifically designed for measuring cookware temperatures within the 70°C to 250°C range. It uses the industry-standard TO39 package, supports a 5V power supply voltage, and can be easily integrated into induction cooker designs via an SMBus digital interface.

The MLX90617 chip integrates an infrared thermopile detection element, signal conditioning ASSP, low-noise amplifier, 17-bit ADC, and high-performance DSP unit within the TO39 package, enabling high-precision, high-reliability temperature measurement functionality.

In-depth development

“Initially, we developed the MLX90617 to address customer needs, but we faced numerous challenges when processing weak short-wave infrared signals, which once made us question its feasibility,” shared Joris Roel, Marketing Manager at Melexis, candidly. “However, through in-depth R&D and application testing, we not only successfully overcame these obstacles but also launched a solution that not only meets customer needs but is also cost-effective and easy to use.”