Texas Instruments Sensors

Digital sensors (I2C/SPI) offer calibrated accuracy, easy MCU interface, and no need for ADC. Analog sensors (voltage/current output) provide continuous monitoring and faster response. Digital sensors like TMP117 offer ±0.1°C accuracy with no calibration. Analog sensors like LM35 are simpler but require ADC and calibration for accuracy. Choose digital for ease of use and accuracy. Choose analog for simple applications or very fast response times.

Use digital sensors for accuracy and ease of integration. Use analog for simple cost-sensitive applications.

Accuracy requirements by application: Human comfort (HVAC): ±1-2°C is sufficient. Industrial process control: ±0.5°C typical. Medical devices: ±0.1-0.2°C required. Scientific/lab equipment: ±0.01-0.1°C. Consider total error budget including sensor accuracy, drift over time, and self-heating. TMP117 offers ±0.1°C from -55°C to +150°C without calibration. Lower cost sensors like TMP75 offer ±1-2°C accuracy suitable for less critical applications.

Match sensor accuracy to application requirements. Consider total system error budget.

Current sensors measure current without breaking the circuit. Shunt-based sensors (INA series) use a small resistor and measure voltage drop - accurate and low-cost but require galvanic connection. Hall-effect sensors measure magnetic field from current - provide isolation but less accuracy. TI's INA series offers high-side or low-side measurement with integrated amplifiers. Use current sensors for power monitoring, overcurrent protection, and battery management. Choose based on accuracy needs and isolation requirements.

Use shunt sensors for accuracy, Hall-effect for isolation. Select range based on expected current.

Self-heating occurs when the sensor's power dissipation raises its temperature above ambient. Power = V × I for digital sensors. At 3.3V and 100µA, power is 330µW. In still air, this can raise temperature by 0.1-0.5°C depending on package. Minimization techniques: use low-power modes, reduce conversion frequency, ensure good thermal contact to PCB, use larger packages with better heat dissipation, or compensate in software. For highest accuracy, use one-shot conversions with long intervals between measurements.

Use low-power modes and minimize conversion frequency. Consider self-heating in error budget.

Multiple I2C sensors with the same address can be handled by: 1) I2C multiplexer (TCA9548A) - creates separate buses, 2) Address pins - some sensors have pins to select alternate addresses, 3) GPIO-controlled power - power sensors on/off to enable one at a time, 4) Different buses - use separate I2C controllers if available. TCA9548A is the cleanest solution, supporting up to 8 devices with the same address. Software overhead is minimal - just select channel before communication.

Use I2C multiplexer for multiple same-address devices. Use address pins if available.