Cuizhan Microelectronics Launches Intelligent Ultra-low Power Digital Pyroelectric Sensor

Shanghai, January 8, 2021, Grecon Microelectronics (Shanghai) Co., Ltd. (Grecon) recently announced the launch of an ultra-low power digital chip M9401 for human passive infrared (PIR) applications. In this solution, the pyroelectric infrared sensor detects the human body radiation signal in a non-contact manner, and converts the signal into an electrical signal and inputs it to the chip for signal processing. The chip’s operating current is extremely low, with a typical power consumption of only 4.5µA, and has a wide voltage operating range of 1.4V-3.6V in normal operating mode. At present, the modified chip is already in mass production, and it can provide users with test wafers or DFN8L2X2 packages in batches, as well as products in other package forms defined by users.

M9401 is specially designed for intelligent single-chip pyroelectric sensors, reducing the external single-chip and operational amplifier circuits. It has a very small chip area, special input and output circuit structure and on-chip signal processing capabilities. It can be integrated in the PIR probe and directly connected to the ceramic sensitive element, detects human body induction and outputs trigger events. We call it a smart PIR sensor (bottom right), which replaces the traditional analog probe plus external chip discrete solution (bottom left). This intelligent solution has the advantages of high sensitivity, extremely low power consumption, simple and flexible peripheral circuit configuration, high reliability, and excellent anti-RF interference ability. Based on the above advantages, the solution can be applied to a very wide range of applications while reducing the number of external components as much as possible.

M9401 is a brand-new intelligent pyroelectric PIR (Passive Infrared) sensor signal conditioning chip, which integrates all the functional modules required by passive infrared sensors. The chip M9401 is a high-impedance differential signal input mode, which can be directly connected to the pyroelectric sensor, and has a built-in 15-bit ADC and algorithm logic for human body movement. The input PIR analog signal is first converted into a digital signal by ADC, filtered and transmitted to the internal logic circuit for calculation. When the chip reaches the trigger condition, the MTRG pin of the push-pull structure outputs a trigger event, that is, a high-level signal to drive External MCU or other load circuit. The output high level holding time of MTRG and the sensor sensitivity threshold can be set by the resistor divider, and the internal 7-bit ADC collects the pin level signal for subsequent analysis and processing. At the same time, the chip provides DOCI communication interface and self-check mode, which is convenient for users to develop and test in mass production.

M9401-Low-power intelligent pyroelectric signal conditioning chip

main feature

· Compatible with differential mode and common mode PIR signal input mode

· Wide voltage working range 1.4V~3.6V

· Very low operating current, 4.5µA typical

· 128 gears “ON-TIME” output time is continuously adjustable

· Compatible with differential mode and common mode PIR signal input mode

· Four test modes to choose from

· Single wire communication interface mode (DOCI)

Application area

· Digital PIR sensor, high-end application scenarios

· Human intrusion detection

· Industrial security, alarm

· Smart buildings, smart lighting, smart homes

Typical application circuit

Built-in M9401-intelligent pyroelectric sensor minimum working system

The picture above is the smallest working system of the intelligent pyroelectric sensor with built-in M9401 chip. A new intelligent PIR signal conditioning chip M9401 is integrated in the pyroelectric digital probe. The sensitivity of the sensor and the value of ONTIME can be designed with a resistor divider or a potentiometer on these two pins, and the different working states of the sensor can be adjusted by adjusting these hardware circuits. In addition, the OEN pin can be connected to an external photoresistor to control the sensor to work alternately in the daytime, day and night environment. Compared with the previous smart digital probe, the power consumption of the probe using the M9401 chip is greatly reduced. At the same time, its self-checking function can meet the automatic detection of semi-finished products of the probe manufacturer, saving the cost of the subsequent detection process.