In the fields of intelligent security, energy-saving lighting, and automatic control, CXRT2131, as a digital analog hybrid chip designed specifically for microwave and infrared signal processing, has become an ideal choice for battery powered systems due to its ultra-low power consumption, high integration, and flexible triggering mechanism. This article will delve into its core characteristics, typical application circuits, and design techniques to assist engineers in efficiently developing induction products.
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[ CXRT2131 ]"
Introduction
In the fields of intelligent security, energy-saving lighting, and automatic control,CXRT2131As a digital analog hybrid chip designed specifically for microwave and infrared signal processing, it has become an ideal choice for battery powered systems due to its ultra-low power consumption, high integration, and flexible triggering mechanism. This article will delve into its core characteristics, typical application circuits, and design techniques to assist engineers in efficiently developing induction products.
1、 Core feature: Why choose CXRT2131?
1.1) Extremely low static power consumptionPower consumption<45μ when powered by 3V; A. When powered by 5V,<75μ A， Significantly extend battery life.
1.2) High compatibility and anti-interference abilityHigh input impedance operational amplifiers are suitable for various sensors, and bidirectional amplitude detectors effectively suppress environmental noise.
1.3) Flexible timing control:Built in delay timer (Tx) and lockout timer (Ti), adjust oscillation frequency through external RC (formula:Tosc=0.4R· C）Realize precise timing of 5&ms~50s.
1.4) Wide voltage operation+3V~+5.5V power range, compatible with lithium battery/button battery power supply solutions.
2、 Analysis of Key Pin Functions
| pin | name | Functional Description |
|---|---|---|
| 3 (VC) | Trigger prohibition end | Lock the output when the voltage is less than 0.2VDD; &Allow triggering at 0.2VDD (combined with photoresistor to achieve day night mode switching) |
| 4 (A) | Trigger mode end | A=“ 1” Repeatable triggering (signal continuously refreshes Tx); A=“ 0” Single trigger (reset after Tx+Ti) |
| 6 (OUT) | signal output | Strong driving capability: at 5V± 25mA (can directly drive LED/relay) |
| 7 (CT) | Oscillation control | External capacitor Cr+pull-up resistor RT set frequency (e.g. R=100K, C=1nF→ f=20kHz） |
3、 Typical application scenarios and circuit design
3.1. Human body induction lighting system(Figure 6-1a)
3.1.1) Core componentsPIR infrared sensor+CXRT2131+S8050 transistor driven LED.
3.1.2) Anti interference design：
3.1.2.1)The gain of the first stage operational amplifier is A1=R3/R2 (typical value 300 times), the second stage is fixed at 30 times, and the total gain is 9000 times.
3.1.2.2)C3 (10nF) filters out high-frequency noise, and C2 (10μ F) stabilizes the signal with a DC blocking capacitor.
2. Relay controlled security equipment(Figure 6-1b) The S8050 control relay is driven through the OUT pin, and the HT7533 LDO isolates power supply noise to avoid accidental triggering due to VDD fluctuations.
3. Dual mode photosensitive and microwave induction scheme(Figure 6-1c):Photoresistor (RG) connected to VC terminalWhen the light intensity is greater than or equal to the threshold, turn off the trigger to achieve“ Sleep during the day and start at night;.
4、 Advanced Design Techniques
4.1. Timer Model Selection Guide
| model | Tx (hours) | Ti (hours) | Proportion K | Applicable scenarios |
|---|---|---|---|---|
| CXRT2131A | 100,000 | 20,000 | five | Short latency (<15s) |
| CXRT2131G | 100,000 | 2,000 | fifty | Long delay+short blockade (anti-interference) |
Calculation ExampleWhen Tosc=50μ At s time (R=100K, C=1nF), the total timing time of CXRT2131D is:
Tx = 100,000 × 50μs = 5s Ti = 5,000 × 50μs = 0.25s t_total = 5.25s
4.2. Principle of trigger mode selection
4.2.1) Cannot be triggered repeatedly (A=“ 0”)Suitable for alarm devices to avoid continuous false alarms.
4.2.2) Repeatable triggering (A=“ 1”)Suitable for lighting systems, keeping the human body constantly moving and constantly on.
4.3. Key to Power Supply Design
4.3.1)Add 10μ F+0.1μ F-capacitor combination filtering, using LDO such as HT7533 to isolate motor/relay surge current.
5、 Extreme parameters and electrical characteristics
5.1) Absolute maximum value(Exceeding will result in permanent damage):
5.1.1) Power supply voltage Vd: -0.3V~+6V
5.1.2) Working temperature: -45 ℃~+85 ℃
5.2 Typical Performance（Vdd=5V, TA=25℃）：
5.2.1) Static current ICC: 65μ A (typical value)
5.2.2) OUT drive capability: Output high level≥ 4.5V at 10mA load
Conclusion
The CXRT2131 greatly simplifies the development process of microwave infrared induction products through highly integrated design (operational amplifier+comparator+dual timer). Its milliampere level power consumption and flexible triggering logic are particularly suitable for battery powered smart homes and IoT terminal devices. Developers can choose the appropriate model suffix (A~G) according to their actual needs, and optimize the RC parameters to balance sensitivity and anti-interference.
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Selection Guide for Related Chips; More similar products .....
| Microwave infrared induction; Infrared Induction | ||||||
| model | Working Voltage | quiescent current | feature | encapsulation | remark | |
| CXRT2124 | 3-5V | 50uA@VDD =3V | low power consumption | SOP16 | Microwave infrared induction compatible with BISS0001 | |
| 100uA@VDD =5V | ||||||
| CXRT2122 | 3-6V | 35uA@VDD =3V | low power consumption | SOP8 | The microwave infrared induction package is small, and the CXRT2124 has a simpler peripheral design | |
| 65uA@VDD =5V | ||||||
| CXRT2130 | 3-6V | 45uA@VDD =3V | low power consumption | SOP8\CPC8 | Microwave infrared induction is simpler than the CXRT2122 peripheral, and it lights up during the day when it is in a photosensitive state | |
| 75uA@VDD =5V | ||||||
| CXRT2131 | 3-5.5V | 45uA@VDD =3V | low power consumption | SOP8\CPC8 | Under microwave infrared induction photosensitive state, the light does not turn on during the day | |
| 75uA@VDD =5V | ||||||
| rolling code | ||||||
| model | Working Voltage | quiescent current | feature | encapsulation | remark | |
| CXRT2121 | 3.5-13.0V | 1uA | low power consumption | SOP8 | Rolling code encoding chip | |
| Power amplifier chip | ||||||
| model | Working Voltage | quiescent current | Maximum output power | efficiency | feature | encapsulation |
| CXAR41222 | 3-5V | 3mA@VDD =3V | 3W | 90% | 3W single channel D-class unfiltered audio amplifier | SOP8 |
| 5mA@VDD =5V | ||||||
| CXAR41218 | 2.2-5.2V | 3.6mA@VDD =3V | 3W | 90% | 3W dual channel unfilteredD-class audio amplifier | SOP16 |
| 5mA@VDD =5V | ||||||
| CXAR41219 | 2.5-5.5V | 6mA@VDD =5V | 3W | 88% | 3W anti chipping function dual channel no filterD-class audio amplifier | SOP16 |
| Operational amplifier comparator; Amplifier | ||||||
| model | Working Voltage | quiescent current | Maximum offset voltage | bandwidth | feature | encapsulation |
| CXAR41214 | 2.7-5.5V | 80uA | 6mV | 1M | Low power consumption, rail to rail input-output dual channel operational amplifier | SOP8 |
| CXAR41215 | 2.7-5.5V | 2.7-5.5V | 6mV | 4M | Low power consumption, rail to rail input-output high-speed dual channel rail to rail operational amplifier chip | SOP8 |
| CXAR41327 | 2.7-5.5V | 0.43mA | 6mV | 6M | Operational amplifier comparator, high-speed rail to rail dual channel operational amplifier | SOP8 |
| CXAO42299 | 3-18V | 1.5mA | 5mV | 1M | Operational amplifier comparator with four independent operational amplifiers | SOP14 |
| CXAO42300 | 3-30V | 0.7mA | 5mV | 1M | Operational amplifier comparator dual channel operational amplifier chip | SOP8 |
| CXAO42301 | 2-36V | 0.8mA | 5mV | 1M | Operational amplifier comparator, dual independent comparator | SOP8 |
