1. One-Sentence Description
The LF 305-S is an industrial-grade current sensor based on closed-loop Hall-effect compensation technology, supporting DC/AC/pulse current measurement (0–±500A). With ±0.5% high accuracy and 100kHz bandwidth, it is designed for precision control in harsh electromagnetic environments.
2. Core Features
- Closed-Loop Hall Compensation Architecture: Eliminates temperature drift and nonlinear errors through magnetic flux balance principle, achieving ±0.1% typical linearity.
- Dual Insulation Protection: UL 94-V0 flame-retardant housing + 3.8kVAC withstand voltage design, compliant with EN 50178/IEC 61010 dual certification.
- Wide-Range Adaptability: Operates in an ultra-wide temperature range of -40°C to +85°C, supports ±12V to ±20V wide-voltage power supply.
- Ultra-Fast Response: <1μs step response (90% output), 100kHz bandwidth (-1dB).
- Modular Design: M4 screws/PTKA screws dual installation options, compatible with standard rails and PCB integration.
3. Core Technical Specifications
| Category | Key Parameter | Typical Value |
| Electrical Performance | Rated Current (IPN) | 300A |
| Secondary Current (ISN) | 150mA | |
| Total Error @25°C | ±0.5% | |
| Dynamic Performance | Delay Time (10%~90%) | <1μs |
| Bandwidth (-1dB) | DC~100kHz | |
| Environmental Adaptability | Operating Temperature | -40°C~+85°C |
| Storage Temperature | -40°C~+85°C | |
| Safety Protection | Impulse Withstand Voltage | 10kV (1.2/50μs) |
| Creepage Distance/Electrical Clearance | 11.1mm/10.6mm |
4. The Story Behind the Chip
The LF 305-S was born from the urgent demand for equipment intelligence in Industry 4.0. Traditional current transformers faced challenges like magnetic saturation and insufficient frequency response in high-frequency, high-voltage scenarios. The LEM R&D team spent three years overcoming three major technical barriers:
- Nano-Level Hall Element Array: Achieves digital sampling of magnetic field distribution through MEMS technology.
- Dynamic Compensation Algorithm: Integrates FPGA for real-time correction of temperature drift and phase shift.
- Composite Insulation Material: Uses polyimide + glass fiber composite substrate to enhance voltage resistance.
This technological breakthrough has enabled the sensor to rapidly replace traditional solutions in emerging fields like EV charging stations and photovoltaic inverters.
5. Innovative Design Philosophy
The LF 305-S adopts a **”Triple Redundancy Architecture”**:
- Electrical Isolation Layer: A 3μm alumina insulation layer formed by physical vapor deposition (PVD).
- Dual-Core Signal Processing: Main control chip + monitoring unit for real-time cross-verification.
- Thermal Management Channel: Bottom hollow design paired with thermal grease achieves 8W/mK heat dissipation efficiency.
This modular design ensures ±0.3% accuracy even at -40°C, improving reliability by 40% compared to similar products.
6. Typical Application Scenarios
- New Energy Sector: Photovoltaic MPPT tracking systems (±500A large current monitoring).
- Industrial Automation: Servo motor vector control (100kHz current loop closed-loop).
- Power Electronics: UPS input/output characteristic analysis (10kV surge test passed).
- Rail Transit: Traction converter IGBT module protection (compatible with -40°C cold start).
7. Ultimate Performance Advantages
- Extreme Bandwidth: 100kHz response easily handles SiC MOSFET high-frequency switching noise.
- Superior Overload Capacity: Supports 3x rated current for 3-second pulse tests.
- Zero Hysteresis: Core uses permalloy + laser welding process, residual magnetism <10ppm.
- Smart Diagnostics: Built-in self-test function, feedbacks sensor health status via current output.
8. Must-Read for Engineer Selection
- Key Parameter Matching: Ensure IPN ≥ peak measured current, ISN matches backend ADC range.
- Power Supply Selection: ±20V power supply delivers optimal SNR (minimum load impedance 0.8Ω).
- Installation Notes: Primary aperture of 20.1mm must fully penetrate conductor to avoid edge effects.
- Certification Compliance: Medical/rail transit fields require additional CTI/EMC test reports.
- Lifetime Prediction Model: Refer to JEDEC standards—every 10°C increase reduces lifespan by 50% (junction temperature ≤125°C).
Technical Upgrade Tip: For new energy vehicle applications, the enhanced version of LF 305-S (explosion-proof packaging + ISO 26262 certification) is recommended, capable of withstanding IEC 60068-2-64 Class 3 vibration levels.
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