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sensor:cjmcu_8221 [2026/02/12 18:55] – created - external edit 127.0.0.1sensor:cjmcu_8221 [2026/02/12 19:10] (current) – vamsan
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 ====== LamaPLC: CJMCU-8221 Analog Devices Precision instrumentation amplifier module ====== ====== LamaPLC: CJMCU-8221 Analog Devices Precision instrumentation amplifier module ======
 +{{ :sensor:cjmcu_8221_1.png?120|CJMCU-8221 Analog Devices Precision instrumentation amplifier module}}
 +The **CJMCU-8221** is a high-performance, gain-programmable precision instrumentation amplifier module based on the **AD8221AR** chip by Analog Devices. It is specifically designed to amplify small signals in noisy environments with high accuracy.
  
-The CJMCU-8221 is a high-performance, gain-programmable precision instrumentation amplifier module based on the AD8221AR chip by Analog Devices. It is specifically designed to amplify small signals in noisy environments with high accuracy.+=== Key Technical Specifications === 
 +  * **Core Chip:** Analog Devices AD8221. 
 +  * **Programmable Gain:** Set via a single external resistor from 1 to 1000. 
 +  * **Supply Voltage:** Supports single or dual supplies from ±2.3 V to ±18 V. 
 +  * **High CMRR:** Minimum Common-Mode Rejection Ratio (CMRR) of 80 dB to 90 dB (at G=1), enabling rejection of wideband interference and line harmonics. 
 +  * **Low Noise:** Input voltage noise of approximately 8 nV/√Hz at 1 kHz. 
 +  * **Form Factor:** Compact MSOP package on a breakout board for easy prototyping. 
  
-Key Technical Specifications+=== CJMCU-8221 Pinout === 
 +^Pin #^Mnemonic^Description| 
 +|1|-IN|Negative Input Terminal for the differential signal.| 
 +|2|RG|Gain Setting Terminal. Connect one end of the gain resistor here.| 
 +|3|RG|Gain Setting Terminal. Connect the other end of the resistor here.| 
 +|4|+IN|Positive Input Terminal for the differential signal.| 
 +|5|-VS|Negative Power Supply. Connect to negative rail (e.g., -5V) or Ground for a single supply.| 
 +|6|REF|Reference Voltage. Sets the output "zero" level. Typically connected to Ground (GND).| 
 +|7|VOUT|Output Signal. The amplified result of (+IN) - (-IN).| 
 +|8|+VS|Positive Power Supply. Connect to positive rail (e.g., +5V to +18V).|
  
-Core Chip: Analog Devices AD8221. +  * **Dual vs. Single Supply:** While it can operate on a single supply (4.6V to 36V), using a dual supply (±2.3V to ±18V) is recommended to ensure the output can swing fully to zero. 
-Programmable Gain: Set via a single external resistor from 1 to 1000. +  * **REF Pin:** Do not leave this pin floating. Tie it to GND for a 0V reference or to a specific voltage if you need to level-shift the output. 
-Supply Voltage: Supports single or dual supplies ranging from ±2.3 V to ±18 V. +  * **Decoupling:** Always place bypass capacitors (e.g., 0.1µF) between the supply pins and ground to minimize noise.
-High CMRR: Minimum Common-Mode Rejection Ratio (CMRR) of 80 dB to 90 dB (at G=1), allowing it to reject wideband interference and line harmonics. +
-Low Noise: Input voltage noise of approximately 8 nV/√Hz at 1 kHz. +
-Form Factor: Compact MSOP package on a breakout board for easy prototyping. +
  
-Gain Calculation+=== Gain Calculation ===  
 +The gain (G) of the module is determined by the external resistor (R<sub>G</sub>) connected across the R<sub>G</sub> pins. Use the following formula:
  
-The gain (G) of the module is determined by the external resistor (RG) connected across the RG  pins. Use the following formula: +^Target Gain^Resistor (R<sub>G</sub)|
- +
-^Target Gain^Resistor (RG)|+
 |1|Open (No resistor)| |1|Open (No resistor)|
-|10|| +|10|5.49 kΩ| 
-|100||  +|100|499 Ω|  
-|1000|| +|1000|49.4 Ω|  
 + 
 +//Many breakout boards come with a pre-soldered 499 Ω resistor, setting the default gain to approximately 100.//  
 + 
 +=== Arduino Code Example === 
 +<code c> 
 +void setup() { 
 +  Serial.begin(9600); 
 +} 
 + 
 +void loop() { 
 +  int sensorValue = analogRead(A0); 
 +  // OUT Pin: Connect to an Arduino Analog Input (e.g., A0) 
 +  float voltage = sensorValue * (5.0 / 1023.0); // Convert to voltage 
 +  Serial.println(voltage); 
 +  delay(100); 
 +} 
 +</code>
  
 {{tag>CJMCU-8221 AD8221AR Analog_Devices amplifier sensor}} {{tag>CJMCU-8221 AD8221AR Analog_Devices amplifier sensor}}