II-VI Marlow

Advances in Microcontroller Based Temperature Control

This entry was posted in temperature control and Microcontroller on July 08, 2016 by II-VI Marlow Industries

The semiconductor manufacturing industry has continued to advance state-of-the-art processing capability resulting in lower cost, reduced power, faster Central Processing Units (CPUs) and denser memory. These continuous improvements enable highly integrated smaller footprint integrated circuits (ICs), and System-on-Chip (SoC) technologies.

Microcontroller Advancements Enable Next Generation Temperature Control

As a result, microcontroller (MCU) advancements continue to enable the development of next-generation compact consumer products, scientific instruments, medical devices and industrial controls with enhanced features and connectivity options. II-VI Marlow has taken advantage of this trend by developing and offering advanced thermoelectric (TE) temperature controllers to augment our thermoelectric cooler product line, which is well known for world class quality combined with ability to quickly customize and mass produce thermoelectric modules to fit the specific needs of our customers across multiple industries.

Microcontroller and Thermoelectric Cooler Integration

Microcontrollers are often confused with microprocessors, which are better known due to their association with the Personal Computer (PC) market. Microprocessors contain a general purpose CPU core along with the interface, or bus structure, to allow external peripherals (memory, input/output devices, etc) to interface with the CPU. Microcontrollers incorporate a CPU core along with embedded peripherals in a single IC. The following peripherals are examples of what may be embedded:

• 8/16/32-bit CPU Core
• GPIO – General Purpose Input/Output
• ADCs – Analog-to-Digital Converters
• DACs – Digital-to-Analog Converters
• PWMs - Pulse Width Modulators
• USARTs – Universal Synchronous/Asynchronous Receiver/Transmitter
• SPI Bus – Serial Peripheral Interface
• I2C Bus – Inter-integrated Circuit

II-VI Marlow utilizes MCUs in programmable TE temperature controllers. The CPU core executes application specific embedded software instructions, including closed-loop control algorithms, efficiently regulating thermoelectric temperature to a programmable set point that can be input via the Bluetooth, Wi-Fi or RS232/485 communication ports.

Microcontroller Peripheral TE Controller Function
GPIO Select heating or cooling
ADC Convert analog voltage to a numeric representation
DAC Convert the digital signal back to the analog interface
PWM Convert numeric value to an average analog representation by varying the duty cycle of a square wave with a fixed carrier frequency
USART Enables full duplex communication between devices
SPI Bus Enables high speed communication between compliant ICs on the Printed Circuit Board Assembly (PCBA)
I2C Bus Enables high speed communication between compliant ICs on the PCBA

 

Typical PWM carrier frequencies will range from 1–10 kHz in most TE applications. The sampling frequency, PWM refresh rate and Proportional Integral Derivative (PID) tuning parameters are often optimized and may be application specific for a given thermal mass and overall system time constants. Humidity sensor integration is optional to provide additional feedback for customized performance over a wide range of operating conditions. The H-Bridge Amplifier is bi-directional to support both heating and cooling, while implementing thermal management features to assure reliability and safe operation. The serial memory device is used to store configuration, manufacturing and application specific data such as tuning parameters.

The integrated peripherals in the MCU coupled with the II-VI Marlow embedded software library can result in rapid integration and customization of common process parameters and user interfaces.

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Summary

II-VI Marlow TE temperature controllers provide features including automated digital calibration, digital closed loop control, embedded diagnostics and multiple connectivity options, including Bluetooth, Wi-Fi and RS232/RS485, to better serve Programmable Thermoelectric Temperature Control Applications. The embedded software architecture is modular and supports firmware over-the-air (OTA) updates that will expedite customization and insure optimization throughout the product life cycle.

Have a custom project? Contact II-VI Marlow today.

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