Infrared thermometer is designed to challenge and device selection

Because of its speed, accuracy, efficiency and cost advantages, infrared (IR) digital thermometers have replaced traditional Mercury thermometer.

Digital ear thermometer with thermopile sensors measure the eardrum dissemination of infrared heat, the heat reflecting the lower temperature shiqiu.

Thermopile infrared sensor consists of a concatenation of multiple thermocouples.

Each thermocouple consists of two different metals, is not the same when the junction temperature will produce a voltage. Thermocouple is located in the hot zone of thermopile and cold zones. Nexus of cold junction temperature stability of welded together, and the environment temperature isolation. Node of the hot end exposed the eardrum of incident radiation. In order to provide effective thermal, heat in the heat, the node is the node and the cold is quarantined. Usually use electric regulator on thermocouple cold measurement nodes to provide precise temperature measurement. Some of the thermopile sensors with built-in heating regulator, can measure temperature, thus allowing to calculate the target temperature.

Thermopile output signal and frequency of relations are very stable, it has a direct and proportional to the incident radiation intensity.

Detection sensor generates 100 μ μ V ~ 900 V output voltage range, the measurement of weak signal is a signal conditioning circuitry for a serious challenge.

Solution

Infrared digital clinical thermometer, battery-powered portable applications requiring low power consumption and use of single-supply operation.

High-precision AD8538 from zero amplifier with low power consumption, low input bias current, very low offset voltage, extremely low offset drift and high open-loop gain, to ensure optimal system performance. AD8538 operating current is low, the maximum supply current 180 μ A, VOS maximum 13 μ V, typical value is TCVOS 30nV/° C. AD8538 have rail-to-rail input/output, voltage 2.7V, 5-lead TSOT package.