The **LA55-P** is a high-performance Hall Effect current transducer commonly used for the electronic measurement of DC, AC, and pulsed currents. It provides galvanic isolation between the primary circuit (high power) and the secondary circuit (electronic control). --- ### 1. Key Technical Specifications The LA55-P operates based on **Closed Loop (Compensated) Hall Effect** technology, which offers high accuracy and linearity. | Parameter | Value | | :--- | :--- | | **Primary Nominal Current ($I_{pn}$)** | 50 A | | **Measuring Range** | 0 to ±70 A | | **Secondary Nominal Current** | 50 mA | | **Conversion Ratio** | 1 : 1000 | | **Supply Voltage ($V_c$)** | ±12 V to ±15 V (±5%) | | **Accuracy** | ±0.65% of $I_{pn}$ | | **Frequency Bandwidth** | DC to 200 kHz | --- ### 2. Internal Electronic Components & Principle The device consists of several critical electronic sub-sections integrated into one module: 1. **Magnetic Core:** A soft magnetic toroid that concentrates the magnetic field generated by the primary current. 2. **Hall Generator:** A semiconductor sensor placed in the air gap of the core that detects the magnetic flux. 3. **Operational Amplifier (Op-Amp):** An internal high-gain amplifier that processes the Hall voltage. 4. **Secondary Compensation Coil:** A winding of 1000 turns ($N_s$) that creates an opposing magnetic field to "null" the flux in the core. 5. **Output Stage:** A push-pull transistor stage that drives the secondary current ($I_s$) through the measurement resistor. --- ### 3. Connection Diagram & Pinout The LA55-P typically features 4 pins for PCB mounting. | Pin | Symbol | Function | | :--- | :--- | :--- | | 1 | **+Vc** | Positive Supply (+12V to +15V) | | 2 | **-Vc** | Negative Supply (-12V to -15V) | | 3 | **M** | Measurement / Output signal | | 4 | **0V** | Common Ground (Reference) | #### Measurement Circuit Logic To read the current with a microcontroller or ADC, you must connect a burden resistor ($R_m$) between the **M** pin and the **0V** ground. ```cpp // V_out = I_primary * (Secondary_Turns / Primary_Turns) * R_m // Example: If Primary = 50A and R_m = 100 Ohms // Secondary Current = 50A / 1000 = 0.05A // Output Voltage = 0.05A * 100 = 5.0V ``` --- ### 4. Typical Applications * **Variable Speed Drives:** Monitoring motor current. * **Battery Management Systems (BMS):** Tracking charge/discharge cycles. * **Uninterruptible Power Supplies (UPS):** Ensuring stable power delivery. * **Welding Inverters:** Precise control of high-current output.