The **HMS150-15-R** is a high-performance current transducer manufactured by **LEM**. It is designed for the electronic measurement of DC, AC, and pulsed currents with galvanic isolation between the primary circuit (high power) and the secondary circuit (electronic circuit). --- ### 1. Key Technical Specifications The following table summarizes the primary electrical characteristics of the HMS150-15-R: | Parameter | Value | | :--- | :--- | | **Nominal Current ($I_{pn}$)** | 150 A | | **Measuring Range ($I_{pm}$)** | 0 to ±450 A | | **Supply Voltage ($V_c$)** | +5 V DC (Single Supply) | | **Output Type** | Ratiometric Voltage Output | | **Output Voltage @ $I_{pn}$** | $V_{ref} \pm 1.25$ V | | **Reference Voltage ($V_{ref}$)** | 2.5 V | | **Accuracy** | ±0.5% (at +25°C) | | **Bandwidth** | DC to 50 kHz (-3 dB) | --- ### 2. Core Electronic Components & Technology The device utilizes several critical electronic principles to function effectively: * **Open Loop Hall Effect Technology:** It uses a Hall effect sensor combined with a magnetic core. The magnetic flux produced by the primary current is concentrated in the magnetic circuit and measured by the Hall cell. * **ASIC (Application Specific Integrated Circuit):** Inside the module, a custom ASIC processes the Hall voltage, provides temperature compensation, and manages the ratiometric output to ensure high linearity. * **Galvanic Isolation:** The design provides physical and electrical separation between the high-current busbar and the low-voltage control electronics, protecting sensitive MCUs (Microcontrollers). --- ### 3. Connection Pinout The HMS series typically features a 4-pin interface for the secondary side: | Pin Number | Name | Function | | :--- | :--- | :--- | | 1 | **$V_c$** | Positive Supply Voltage (+5V) | | 2 | **0V** | Ground / Reference | | 3 | **$V_{out}$** | Measured Current Output Signal | | 4 | **$V_{ref}$** | Reference Voltage (Output or Input) | --- ### 4. Application Integration When integrating this part into a circuit, developers usually follow these steps: 1. **Filtering:** Place a decoupling capacitor (typically 100nF) close to the $V_c$ and 0V pins to minimize noise. 2. **ADC Interface:** The $V_{out}$ is fed directly into an Analog-to-Digital Converter. Since it is ratiometric, if the ADC reference is tied to the same 5V supply, errors in supply voltage cancel out. 3. **Mounting:** The HMS series is usually PCB-mounted with the primary conductor passing through the center aperture or via integrated primary pins.