The **MPX53** series (specifically the MPX53GP or MPX53D) is a silicon piezoresistive pressure sensor manufactured by NXP (formerly Freescale). It is designed for a wide range of applications, particularly those requiring a low-cost, high-accuracy sensor with a linear output proportional to applied pressure. --- ## 1. Technical Specifications The MPX53 is part of the "uncompensated" family, meaning the raw output requires external circuitry for temperature compensation and amplification. | Characteristic | Specification (Typical) | | :--- | :--- | | **Pressure Range** | 0 to 50 kPa (0 to 7.25 psi) | | **Supply Voltage ($V_S$)** | 3.0 Vdc (Nominal) | | **Sensitivity** | 1.2 mV / kPa | | **Full Scale Span** | 60 mV | | **Linearity** | ±0.25% to ±0.5% VFS | | **Input Impedance** | 400 $\Omega$ to 550 $\Omega$ | | **Operating Temp** | -40°C to +125°C | --- ## 2. Key Internal Components The sensor utilizes advanced micromachining techniques to integrate the following parts into a single monolithic silicon chip: ### A. Piezoresistive Strain Gauge The core "electronic part" is an **X-ducer** element. This is a single ion-implanted strain gauge. Unlike traditional Wheatstone bridges that use four resistors, the X-ducer uses a single transverse voltage element, which simplifies the design and improves linear repeatability. ### B. The Diaphragm The silicon chip is etched to create a thin diaphragm. When pressure is applied, the diaphragm deflects, creating mechanical stress that changes the electrical resistance of the X-ducer via the piezoresistive effect. ### C. Package Types (Case 344) * **MPX53D:** Basic element (Unported). * **MPX53GP:** Gauge Ported (includes a thermoplastic lead frame and a port for tube connection). --- ## 3. Pin Configuration The MPX53 typically comes in a 4-pin SIP (Single In-line Package) or similar configuration. | Pin Number | Function | Description | | :--- | :--- | :--- | | **1** | **GND** | Ground / Negative Supply | | **2** | **$V_{out}+$** | Positive Output Signal | | **3** | **$V_S$** | Supply Voltage (Positive) | | **4** | **$V_{out}-$** | Negative Output Signal | --- ## 4. Implementation Circuitry Because the MPX53 is an **uncompensated/unconditioned** sensor, you cannot connect it directly to a microcontroller ADC without additional parts: 1. **Instrumentation Amplifier:** Since the output is in millivolts (60mV max), you need an Op-Amp circuit (like an AD620 or INA126) to boost the signal to 0-5V. 2. **Temperature Compensation:** The sensitivity changes with temperature. A thermistor or a software-based correction algorithm is usually required for precision. 3. **Filtering:** A simple RC low-pass filter is recommended at the output pins to reduce high-frequency noise. ```python # Example: Calculating Pressure from Voltage # V_out = Sensitivity * Pressure # Pressure = V_out / 1.2 mV def get_pressure_kpa(milli_volts): sensitivity = 1.2 # mV/kPa return milli_volts / sensitivity ``` ---