In-depth Analysis of MLX91205KDC-AAL-003-RE/TU Chip

1. One-sentence Description

MLX91205KDC-AAL-003-RE/TU is an IMC-Hall® current sensor based on Triaxis® technology, which realizes wide-bandwidth and high-precision AC/DC current measurement through contact magnetic induction, specially designed for harsh industrial and automotive environments.

2. Features

• Non-contact measurement: No physical connection to the current conductor is required, achieving electrical isolation.
• High sensitivity: Integrates a magnetic concentrator (IMC-Hall®) with a sensitivity of 280 mV/mT (typical value).
• Wide bandwidth: Supports DC to 100kHz signals with a response time as low as 8μs.
• Low temperature drift: Offset voltage temperature drift < ±0.3 mV/°C, sensitivity temperature drift < ±200 ppm/°C.
• Low noise: Spectral noise density < 125 nT/√Hz (10Hz–10kHz).
• Surface mount: SOIC-8 package, compatible with automated production.

3. Core Technical Indicators

4. The Story Behind the Chip

The innovation of MLX91205 stems from Melexis' breakthrough improvement in Hall technology. Traditional Hall sensors can only sense vertical magnetic fields, while Triaxis® technology, combining planar Hall elements and ferromagnetic materials (IMC), realizes magnetic field measurement parallel to the chip surface for the first time. The ferromagnetic layer is integrated into the CMOS wafer through post-processing, amplifying and focusing the external magnetic field on the Hall element, increasing sensitivity by more than 10 times. At the same time, temperature drift and mechanical stress interference are suppressed through dynamic offset cancellation technology.

5. Design Concept

Centered on "small size and high robustness":

• Single-axis magnetic induction: Simplifies PCB layout without complex magnetic circuit design.
• Proportional output (VDD/2 reference): Maintains output stability during power supply fluctuations.
• Differential signal path (A_out and CO_out): Suppresses common-mode noise and improves signal-to-noise ratio.
• 8μs fast response: Meets the needs of high-speed scenarios such as motor control.

6. Application Scenarios

• New energy systems: Solar MPPT converters, battery management (BMS) current monitoring.
• Motor control: Real-time feedback of brushless motor phase current.
• Industrial power supplies: AC/DC converters, ±600A high-current bus detection (requires PCB copper foil optimization).
• Automotive electronics: OBC (on-board charger), DC-DC module current protection.

7. Unique Advantages

The "parallel magnetic field sensitivity" architecture is its disruptive advantage:

• Traditional Hall sensors require vertical magnetic circuit installation, while MLX91205 can be directly mounted above PCB conductors, reducing board space by 70%.
• Combined with the IMC layer, it achieves extremely low noise of 125 nT/√Hz (typical competitor value > 200 nT/√Hz) in the same volume, with an accuracy of ±0.5% FS.

8. Essential Knowledge for Engineers in Selection

1. Sensitivity versions:
   • AAL-003 (this model): 280 mV/mT low-field version (±10 mT), suitable for 0–30A current.
   • AAH-003: 100 mV/mT high-field version (±25 mT), suitable for >30A scenarios.
2. Calibration flexibility: Supports customer-defined calibration (see section 12.4). By calibrating offset/sensitivity via MCU, system accuracy can reach ±1%.
3. Layout key points:
   • Differential output must be connected to a >1 MΩ load (Figure 13.2). Avoid capacitive loads >10 pF affecting bandwidth.
   • The power supply terminal must be paralleled with 100 nF + 100 pF ceramic capacitors for EMI resistance.
4. Taboos:
   • Avoid direct mechanical stress on the package (IMC layer is sensitive to stress);
   • Wave soldering requires consulting Melexis for process parameters in advance.

Conclusion: If high-precision, wide-bandwidth current detection at the ±30A level is required in a compact space, MLX91205KDC-AAL-003 is a rare integrated solution in the industry. Its parallel magnetic field induction technology redefines the PCB current sensing design paradigm.