Dust Monitor

Example of Dust Monitor Block Diagram

Circuit Description

Dust Monitor

As the IoT equipment of the air cleaners advances, the dust sensors installed in the air cleaner are not only used for controlling the equipment, but also the data is sent to the cloud, and AI operates the  air cleaner in anticipation of various scenes. In order to transmit the sensed data on the cloud, it is necessary to digitize the sensing signal regardless of whether it is wired or wireless. AD converter (ADC) is generally used to digitally convert 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, high-precision sensors often use delicate sensing elements, and the output signal is often a weak 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. In order to achieve high-precision amplification, high noise performance is required for an operational amplifier for amplifying analog signals of weak sensor outputs to appropriate signal levels at the ADC input. Toshiba offers TC75S67TU, which is an optimum CMOS operational amplifier for amplifying sensor signals. TC75S67TU achieves a low noise level of 6 nV/√Hz (f=1 kHz, GV=40 dB, typical) equivalent input noise voltage.

Stable power supply is 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 operational amplifier is isolated from the power supply for other electronic circuits. The use of Toshiba's LDO regulator TCR3UG series enables high precision power supplies with low current consumption. TCR3UG series has a lineup of 0.1V steps of output voltage. Select the optimum voltage according to the power supply status in the system and the specifications of the sensors and ADCs.

TC75S67TU achieves a low noise level of 6 nV/√Hz (f=1 kHz, GV=40 dB, typical) equivalent input 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)

Toshiba offers a wide choice of LDO regulators in packages ranging from general-purpose to ultra-compact that are suitable for high-performance requirements, such as low noise, high Power Supply Rejection Ratio (PSRR), high output current stability (load transient response), and low current consumption, which are particularly required for advanced analog circuits.

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

Other Circuit Description

Power Management

Motor Drive

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