SOT Temperature Sensors with Period/Frequency Output

This is a low-current temperature sensors with a single-wire output. The number of pins that needed to interface with a microprocessor is minimized by this circuit because it uses a single-wire output. This circuit can be used in many appplication such as critical µP and µC monitoring, cell phones, networking and telecom equipment, hard drives/tape drives, portable battery-powered equipment, medical equipment, automotive electronics and battery packs. Here is the cricuit :

This circuit uses the MAX6576/MAX6577 as temperature sensor because both are low cost. The ambient temperature converted into a square wave with a frequency proportional to absolute temperature by the MAX6577 and the ambient temperature converted into a square wave with a period proportional to absolute temperature (°K) by the MAX6576. So we have two output types , temperature to frequency (Hz) and temperature to period (µs). This circuit requires  +2.7V to +5.5V supply voltage and low 140µA typical supply current. It can be operated in temperature range: -40°C to +125°C. The accuracy of this circuit is ±0.8°C accuracy at +25°C (±3°C max). Also, this circuit has small 6-Pin SOT23 Package and we doesn’t need any external components. [Source: maxim-ic.com]