MI0707A301 Chip‑type Digital Pyroelectric Infrared Sensor

Product Overview

The surface-mount digital pyroelectric sensor MI0707A301 employs a dedicated human‑body infrared processing integrated circuit as its built-in signal processor. The thermal motion signals detected by the pyroelectric sensing element are fed into the digital chip’s high‑impedance input, where they are converted into 16‑bit digital signals and subjected to digital bandpass filtering. The filtered 16‑bit data is then output serially via the DOCI interface.

Product Features

* Low power consumption, energy-efficient and environmentally friendly, with extended battery life.

* Chip‑on‑board package, suitable for SMD reflow soldering.

* Integrated bandpass filter with strong anti-interference performance, effectively suppressing RF interference from mobile phones, Wi‑Fi, and other sources;

* Wide operating voltage range: 2.5V - 5.0V.

* Digital signal output.

* The peripheral circuit is simple.

Product Applications

* Intelligent security protection, including infrared motion detection

* IoT infrared motion detection

* Automatic lighting control for stairwell lights, indoor lights, corridors, etc.

* Solar-powered automatic sensor light

* The smart home appliance sector, including refrigerators, air conditioners, televisions, and more

* Placeholder detection

Electrical Performance Parameters

1. Maximum Rated Parameters

Any electrical stress exceeding the parameters listed in the table below may result in permanent device damage. Operating under these maximum-rated conditions may compromise the device’s reliability.

2. Operating parameters (ambient temperature 25°C)

Filter and Oscillator Parameters
Parameter	Symbol	Minimum value	Typical value	Maximum value	Unit	Note
Low-pass filter cutoff frequency	F L	—	—	7	Hertz
High-pass filter cutoff frequency	F H	—	—	0.44	Hertz
On-chip oscillator frequency	Fosc	—	—	32	kilohertz
Internal block diagram

3. Function Description

a) Bandpass filter

　　A second-order low-pass filter and a third-order high-pass filter are cascaded to form a bandpass filter, with the corresponding passband spanning 0.44 Hz to 7 Hz.

b) DOCI Serial Data Read Timing

　　DOCI serial data reading is divided into two types: reading based on the interrupt signal of the MI0707A301 and forced reading by defining a timing sequence in the microcontroller.

c) Reading based on the interrupt signal from MI0707A301

　　MI0707A301 generates an active interrupt signal every 16 ms, meaning DOCI is pulled high by MI0707A301 and remains high for two system clock cycles. After waiting 100 ns, the microcontroller asserts a rising edge on the DOCI line and then begins reading data. The first bit read is the most significant bit. This process is repeated until all 16 bits have been read. Once the last bit has been read, the microcontroller must force DOCI low and release it immediately. The DOCI timing diagram is shown in Figure 2, where the solid blue line indicates the microcontroller’s drive and the dashed line indicates MI0707A301’s drive.

Figure 1 DOCI Timing Based on Interrupt Signal Readout

① When the DOCI interface is neither in read mode nor equal to 1, the serial interface completes data updating and generates an interrupt‑valid signal, i.e., MI0707A301 goes high, thereby asserting DOCI.

②MI0707A301 Pull up the DOCI line and maintain it for at least two system clock cycles.

③ The microcontroller pulls the DOCI line low for at least 200 ns.

④ The microcontroller generates a rising edge on the DOCI line, and the high level on the DOCI line is maintained for at least 200 ns.

⑤ DOCI line switching status, outputting the most significant bit (MSB) of the data.

⑥ The microcontroller samples the data’s most significant bit (MSB).

⑦ Repeat steps ③, ④, ⑤, and ⑥; the microcontroller samples the second-highest bit of the data.

⑧ Repeat steps ③, ④, ⑤, and ⑥; the microcontroller samples the least significant bit (LSB) of the data.

⑨ After data reading is complete, the microcontroller forces DOCI to a low level and immediately releases the DOCI line.

⑩ Repeat step ① to begin a new read cycle.

Force a read by defining the timing sequence via the microcontroller.

In this readout mode, as shown in Figure 2, the microcontroller ignores interrupt signals, forces the DOCI line high for at least two system clock cycles, and then begins reading data just as it would in interrupt‑mode readout. To ensure that the output data latch is updated, the microcontroller must either release the DOCI line (triggering automatic data update, similar to the interrupt cycle) or force the DOCI line low for at least 64 system clock cycles (forcing a data update).

Figure 2 DOCI timing during forced read defined by the microcontroller

① The microcontroller ignores the interrupt enable signal from MI0707A301 and directly pulls DOCI high.
② The microcontroller pulls the DOCI line high and maintains it for at least two system clock cycles.
③ The microcontroller pulls the DOCI line low for at least 200 ns.
④ The microcontroller generates a rising edge on the DOCI line, and the high level on the DOCI line is maintained for at least 200 ns.
⑤ DOCI line switching status, outputting the most significant bit (MSB) of the data.
⑥ The microcontroller samples the data’s most significant bit (MSB).
⑦ Repeat steps ③, ④, ⑤, and ⑥; the microcontroller samples the second-highest bit of the data.
⑧ Repeat steps ③, ④, ⑤, and ⑥; the microcontroller samples the least significant bit (LSB) of the data.
⑨ After data reading is complete, the microcontroller forces DOCI to a low level and maintains it for at least 64 system clock cycles to finalize the serial‑port data update. Alternatively, as shown in Figure 2, the microcontroller pulls DOCI low and immediately releases the DOCI line, enabling automatic data updating via interrupt mode.
⑩ Repeat step ① to begin a new read cycle.

Regardless of the reading method employed, the data-reading process can be terminated at any time.
As shown in Figure 3, item ⑦, during the read operation, if the DOCI interface remains at a low level for more than one system clock cycle, the data read process is terminated, and the output data latch is updated.

Figure 3: The read operation terminates because DOCI remains at a low level.

As shown in Figure 4, during the read operation, the DOCI interface is forced high, terminating the read process; however, the output data latch is not updated.

Figure 4: The read operation completes due to DOCI being forcibly pulled high.

Figure 5 Data on the DOCI interface

4. Data Format

Note:

*Overflow flag: “0” indicates normal operation, while “1” indicates that the sensor output has exceeded the internal chip’s conversion range, resulting in data overflow.
*Check the parity bit: when bits B16 through B1 contain an odd number of “1”s, the parity bit outputs “1”; when they contain an even number of “1”s, it outputs “0”.
*The last four bits are optional read bits, but the least significant bit of the read data must be “0”; therefore, the number of read bits must be 19, 20, or 23.
*To convert data from B16 to B1 into a signed binary code, the data must be processed as follows: when B16 is “0,” the data remains unchanged; when B16 is “1,” the bits from B15 to B1 are inverted, and 1 is added to B1. The resulting data has B16 as the sign bit—“0” denotes positive and “1” denotes negative—while B15 through B1 represent the binary value, corresponding sequentially to the most significant bit through the least significant bit.

5. External Dimensions

Reference circuit

Product Reference Reflow Soldering Temperature Profile

Welding precautions:
1. Do not exceed the maximum temperature shown on the temperature curve in the figure above; otherwise, sensor performance may degrade.
2. Do not repeatedly perform reflow soldering or subject the component to repeated heating and removal, as this may degrade sensor performance or render it inoperable.
3. After the sensor is mounted, allow it to stand at room temperature before use; we recommend waiting one hour.
4. Sensor failure caused by temperatures or durations exceeding those shown in the diagram is not covered under warranty.

Precautions

MI0707A301 is a digital pyroelectric infrared sensor that detects changes in infrared radiation. For heat sources other than the human body, or in the absence of any heat source, temperature…
Under conditions of variation in angle and movement, detection may not be possible. Please note the following: be sure to verify performance under actual operating conditions.
and reliability.
1. When detecting heat sources other than the human body, the sensor is prone to false alarms.
1.1 When a small animal enters the detection range.
1.2 When the sensor is directly exposed to far-infrared radiation from sunlight, car headlights, incandescent lamps, and similar sources.
1.3 When the temperature in the test area undergoes significant fluctuations due to warm air, cold air, or water vapor from humidifiers in the cold‑room equipment.
2. The phenomenon of the heat source not being detected occurs.
2.1 Between the sensor and the object being detected, there may be materials such as glass or acrylic that are opaque to mid- and far-infrared radiation.
2.2 Within the detection range, when the heat source is nearly stationary or moving at extremely high speed.
3. In the case of an expanded detection area
When the ambient temperature differs significantly from body temperature (by approximately 20°C or more), the detection area may sometimes expand even outside the specified detection range.
4. Notes on Other Uses
4.1 During testing, the Fresnel lens and the finished housing must be installed first (the sensor’s housing must not be left exposed); otherwise, the sensing performance may be compromised, and wind could cause false triggers.
4.2 When stains adhere to the window, detection performance may be affected; please take note.
4.3 The lens supplied with the probe is made of a fragile material (polyethylene). Applying excessive load or impact to the lens may cause deformation and damage, leading to unstable triggering or degraded performance; therefore, such conditions should be avoided.
4.4 Applying electrostatic charges exceeding ±200 V may cause damage. During operation, take care to avoid direct contact with terminals and other components using your hands.
4.5 Frequent and excessive vibration may cause the sensor’s internal sensing element to fracture; handle with care during use.
4.6 Please avoid cleaning this sensor; otherwise, cleaning fluids may penetrate the interior of the device, potentially degrading its performance.