Sensor Input

Example of gas detection circuit for measuring degree of air pollution

Circuit Description


For IoT sensor devices, the sensed data must be sent to the cloud with digital data of the sensing signal whether wired or wireless. Analog Digital Converter (ADC) is generally used to digital data conversion from the analog signal of the sensor output. One of the important indicators of ADC applications for accurate digital conversion is the input of an appropriate level of analog signal. Generally speaking, high-precision sensors often use delicate sensing elements and the output signal is often a minute analog signal. Therefore, in some cases, accurate digital conversion cannot be achieved even if the sensor output is directly input to the ADC. An operational amplifier is used in such cases.

An op-amp for amplifying analog signals from small level of signal sensor outputs to appropriate signal levels on the ACD inputs is required to make the noise performance of the op-amp itself extremely small in order to achieve high-precision amplification. It is also important to reduce the power consumption as much as possible in the application to IoT sensor devices. Toshiba offers a lineup of TC75S67TU, which is an optimum CMOS op amp for amplifying sensor signals in such IoT sensor devices. 

Stable power supplies are also critical to the low-noise performance of TC75S67TU. In order to make the power supply more stable, it is also recommended that the power supply for the op-amp be isolated from the power supply for other electronic circuits. The LDO-regulator's TCR3UG Series enables high-precision power supplies with low current draw. 

TC75S67TU achieves a low noise level of 6 nV/√Hz (f=1 kHz, GV=40 dB, typical) input-converted noise voltage. In addition, by adopting CMOS processing, low power dissipation is also realized at the same time.

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Ultra Low Noise Operational Amplifier,  VNI=6nV/√Hz (Typ.) (VDD=2.5V, f=1kHz)

TCR3UG series can contribute to low power consumption of the set due to its low current consumption characteristics, and has a lineup of 0.1V steps of output voltage as standard.

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Low quiescent current 0.34μA (Typ.) (@IOUT=0mA), VOUT=2.5V (Typ.), IOUT=300mA (Max)



Low quiescent current 0.34μA (Typ.) (@IOUT=0mA), VOUT=3.0V (Typ.), IOUT=300mA (Max)



Low quiescent current 0.34μA (Typ.) (@IOUT=0mA), VOUT=3.3V (Typ.), IOUT=300mA (Max)


Low quiescent current 0.34μA (Typ.) (@IOUT=0mA), VOUT=5.0V (Typ.), IOUT=300mA (Max)

Other Circuit Description

AC-DC Power Supply

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