A programmable monolithic temperature logging device

This paper describes the design and the implementation of a miniature archival temperature monitoring device. The complete system consists of two components: a micro-chip and a small 3 V lithium battery with a charge of 30 mAh. Due to the nature of the application, the tag will spend most of its time in a sleeping mode. The MOS devices constituting the continuously operating oscillator are operated in weak inversion and thus dissipate not more than 1.5 μW. The power consumed by the remainder of the chip´s circuitry is minimized through effective power management. The temperature sampling events are controlled by an application specific protocol, which will be imported from a host PC prior to tag´s deployment. The chip´s memory consists of static RAM and can hold a maximum of 1,024 temperature readings.