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Small Form Factor Temperature Sensors: The Latest Thermal Management Industry Trend

Today, more and more customer applications are concerned about thermal management, however, the problem is that many customers have very limited board space to place a discrete temperature sensor. That’s largely because circuit board form factors are becoming increasingly smaller, making board space real estate compact and critical.  

What’s needed is a tiny, simple and easy to use temperature sensor in the smallest form factor package possible and Microchip has the perfect solution with its AT30TS74 single-channel digital temperature sensor. It’s available in a very small form factor package option called Wafer Level Chip Scale Package (WLCSP) with two different pinouts available. The WLCSP is a true die size package with the overall AT30TS74 size being less than 1mm².  

You might be thinking… how is this possible?  

It’s possible through a special post wafer fab process that routes the device pin signals to a specific solder ball contact and is available in either a 4-ball (four signals) or 5-ball (five signals) WLCSP. The 4-ball package pinout signals are clock and data lines along with ground and Vdd. The 5-ball WLCSP has the same 4-ball signals already noted with one additional signal of the alert pin. The alert pin is important because it allows the temperature sensor the capability to drive an external pin to alert the hardware. 

One added benefit of using the AT30TS74 WLCSP product in any application is it allows for the temperature sensor to be placed as close as possible to the heat source being measured, such as a power source, heat generating component like an MCU, analog component or other heat generating components. The AT30TS74 senses an application’s board temperature through the board traces that are connected to the AT30TS74 pins. Therefore, if the AT30TS74 is placed closer to the heat source being measured on the board, the thermal lag is reduced to provide a better temperature response. This means the temperature sensor can react faster to any temperature changes since the physical propagation delay is reduced.  

Further, this means the AT30TS74 can immediately alert the host controller/MCU faster once its internally preset temperature limits are exceeded and or react faster by driving the available hardware alert signal pin when a temperature limit violation occurs. The AT30TS74 is factory-calibrated and requires no external components to measure temperature and with its high-degree of accuracy, the AT30TS74 is ideal for extended temperature measurements in a wide variety of communication, computer, consumer, environmental, industrial and instrumentation applications. 

It should be noted that the AT30TS74 has user-programmable internal registers to configure the temperature sensor’s performance and response to high and low temperature limit conditions.

The AT30TS74 in the WLCSP package can measure temperatures over the full -55°C to +125°C temperature range and has a typical temperature accuracy of ±1°C over the temperature range of -10°C to +100°C. The results of the digitized temperature measurements are stored in one of the AT30TS74 internal registers, which is readable at any time through the device's serial interface.

The benefits of using the AT30TS74 WLCSPs are:

• Overall size is less than 1mm² making it ideal for extremely densely packed component boards

• Allows the WLCSP to be placed closer to the hot spot to be monitored reducing thermal lag for a better temperature response

• The maximum package height is less than 0.330 mm making it perfect for height constrained applications like wearables, IoT, handheld and consumer products

• Has a ±1°C typical temperature accuracy over a wide temperature range of -10°C to 100°C

• Industry’s widest Vcc range of 1.7 Vcc to 5.5 Vcc to cover a wide Vcc range all with one-part number

To learn more, please visit this page.

Bryce Morgan, Jan 6, 2022