We’ll show you how using an integrated EEPROM provides a simple and cost-effective method of accurate temperature measurement that simultaneously records and tracks the use of the sensor.
This paper details the role of integrated EEPROMs in I 2 C temperature sensors with digital output. In addition to technical explanations, examples are given of how to implement a simple EEPROM write sequence for designs.
I 2 C temperature sensors are integrated circuits that have sold billions since their introduction over 20 years ago. They are a popular solution for temperature monitoring in countless electronic products and systems. They help developers measure and regulate the temperature of their products in real time and respond to temperature extremes.
I 2 C temperature sensors provide a comprehensive solution for temperature monitoring. They measure their internal temperature, convert it to a digital value that can then be easily evaluated using the standard I 2 C protocol. These sensors output digital temperature data, eliminating the need for external components such as A / D converters or post-processing ICs.
A “digital” temperature sensor is factory calibrated to meet well-defined temperature accuracy requirements within a given temperature range. The devices of different suppliers have a maximum accuracy of ± 1 ° C (or better) over a temperature range of -40 to 125 ° C.
If an EEPROM (Electrical Erasable Programmable Read-Only Memory) is integrated into the temperature sensor, the user can store critical application-specific data. The EEPROM is a dedicated nonvolatile memory of various sizes intended as a user memory area.
The main feature of an EEPROM is that each byte-of-memory location can be written more than one million times. The memory is therefore ideal for frequent data changes in almost all products and applications.
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Three reasons why you should use a temperature sensor with integrated EEPROM
First, the integrated memory provides the ability to record critical temperature sensor data locally. Examples are the logging of temperature extremes (shutdown or system failure), the general recording of temperatures, date/time, number of errors as well as logging the duty cycle and many other conditions that should be avoided.
The memory integrated into the temperature sensor is read out to see how often the product has reached a critical temperature. In the event of a warranty claim, this data documents whether the user has operated the product in a constantly high-temperature environment, which may void the warranty or the warranty. Or if the product was overclocked or misused.
The stored data can also help in the search for the cause of the error. Embedded memory reduces the risk of data manipulation and the stored data helps determine if warranty claims are warranted.
The second reason for an integrated EEPROM is that the integrated memory lets you track how end users use the product. This will determine if the user is using certain features or not.
The third reason for using an integrated EEPROM is the storage of factory settings, system configuration and parameters. It would be possible to save how the product was checked with a test program. The test setup and location of the instrument along with its parameters would help with a return as it is understandable how the product was tested at the factory.
In addition, the onboard memory may contain important system configuration data that supports the power-on and initialization process of the system or product. Future product upgrades can be accomplished by simply reprogramming the existing configuration data in a simple programming operation.
Example of a write sequence for checking functions
Maybe you have integrated new features into your current product? Now you want to know if customers use them. Below, I show how this could be implemented with a simple write sequence.
This could be done via two EEPROM byte locations, which are assigned two different values. Thus, you know in advance that these two values store the specific feature or product function. The first-byte location can store the incremented value each time the function is used.
The second-byte location is used as a date and time stamp to see when the function was last used. It also makes sense to get real-time data from customers to know if and when they are using a function. These results are much more valuable than a customer survey or focus group.
An I 2 C temperature sensor with integrated EEPROM, such as the AT30TSE758A, allows manufacturers to take advantage of the three benefits listed above. Accurate temperature control ICs combine a high-precision digital temperature sensor, programmable limits for high and low-temperature alarms, integrated nonvolatile registers, and 8kBit EEPROM in a compact package (Figure 1).
Thus, these sensors are suitable for many applications where the measurement of local temperatures is an integral part of the function and reliability of the system. Figure 1 describes the basic structure of such a sensor.
The described sensor can measure temperatures over a range of -55 to 125 ° C and provides an accuracy of ± 0.5 ° C between 0 and 85 ° C. The results of the digitized temperature measurements are stored in one of the internal registers, which can be read at any time via the serial I 2 C interface of the sensor.
Another way to improve the thermal management of a system is a temperature sensor with nonvolatile registers. This allows the configuration and temperature limits to be saved and maintained even after the device is turned off and on again. This eliminates the need to reconfigure the system after each power-up, allowing for stand-alone operation. Thus, the system does not have to rely on a host controller for device configuration to go through the initialization sequence at power up.
An integrated EEPROM in a temperature sensor offers numerous advantages for implementing thermal management functions and possible design considerations.