Automotive DC Motor EMC Integrated Solution

Learn how Jaron’s JRN/JRT Series combines EMI filtering and surge protection into one device, reducing BOM, improving ISO 7637-2 compliance, and optimizing automotive DC motor performance.

1. Industry Background: EMC Becomes a Hidden Risk in Automotive Motors

In modern vehicles, more than twenty DC motors work simultaneously—for windows, wipers, tailgates, seat adjusters, fuel pumps, and HVAC fans. Each motor generates electromagnetic interference (EMI) and transient surges that travel through harnesses and disturb control modules. This noise can trigger communication errors or permanent damage if not properly filtered.

Traditional protection networks use RC snubbers, TVS diodes, and EMI capacitors. However, this multi-component approach leads to high BOM cost, large board space, poor consistency, and longer validation cycles. As carmakers move toward modular and compact designs, integrated EMC protection is becoming essential.

2. Technical Breakthrough: The JRN/JRT Integrated EMI + Surge Solution

The JRN/JRT series from Jaron uses a multilayer ceramic-MOV composite structure that provides EMI filtering, voltage clamping, and energy absorption in a single device. This integration replaces up to three discrete components, simplifying the design and improving overall stability.

Key Specifications

Parameter items	Numerical range	Engineering significance
Rated voltage	16V – 56V DC	Suitable for 12V/24V/48V platforms
Response time	<25 ns	Rapidly suppress surge spikes
Capacity range	0.1 – 4.7 µF	Simultaneously filters out high-frequency and low-frequency interference.
Clamping voltage	As low as 1.4×VDC	Improve system security margin
Energy absorption	800A–1200A（8µs）	Meets ISO Level 3–4 requirements

Each device can suppress surges up to 1200A with sub-25ns response time, while providing up to 4.7µF capacitance for broadband EMI filtering. It meets ISO 7637-2 and ISO 16750-2 standards, ideal for Tier-1 and Tier-2 automotive suppliers.

Automotive EMC (2).png

3. Working Principle: Fast Response and Low Residual Voltage

EMI Filtering Layer: Employs high-dielectric-constant ceramic to achieve a low-impedance, high-frequency path, effectively reducing switching transients and carbon brush commutation noise.
Varisor Absorbing Layer: Utilizes the high-voltage conduction characteristics of MOV chips to absorb and shunt surge energy to ground.
Collaborative Control: Matching the dielectric thickness with the nonlinear coefficient ensures stable clamping voltage and short response time.

This hybrid design ensures smooth transition from high impedance to clamping state within nanoseconds, avoiding voltage overshoot.

4. Validation and Test Results

Case A: Chengdu Huachuan Denso (Windshield Wiper/Window Lift System)

Platform Voltage: 12V
Traditional Solution: RC + TVS
Replacement Solution: JRN16B105MXG (1µF, 16VDC, 800A)
Testing Standard: ISO 7637-2 Level 3

Results Comparison:

Residual voltage reduced by 38% (from 72V to 45V)
EMI radiation reduced by 18dB
PCB area saved by 58%
Production consistency improved by 30%

Case B: Wenzhou Shenghuabo (Seat Motor/Tailgate System)

Platform Voltage: 24V
Component: JRT26B225MXG (2.2µF, 26VDC, 800A)
Verification Standard: ISO 16750-2 Load Dump
Results: Surge peak voltage controlled below 82V, passed Level 4 test; excellent thermal stability, no degradation after 50 pulses.

5. Comparative Analysis: Advantages of the Integrated Approach

Comparison Dimensions	Traditional RC+TVS	JRN/JRT Integration Solution	Improvement rate
Number of devices	3–4 piece	1 piece	↓70%
Cost control	high	Low	↓40%
Verification cycle	2-3 rounds	Round 1	↓60%
Space usage	100%	45%	↓55%
residual pressure level	70–80V	40–50V	↓35%

The integrated solution reduces component count by up to 70%, shortens validation time, and improves reliability. It simplifies design while maintaining robust compliance with ISO and CISPR standards.

6. Layout and Implementation Tips

The device should be placed as close as possible to the motor brush end, with the shortest distance to the ground loop;
In shielded grounding systems, it should be connected to the main ground or the housing ground first;
In long harness applications, two devices can be connected in parallel to enhance consistency;
Supports reflow simulation and PSpice modeling for system optimization.

7. Future Outlook: Toward Modular EMC Protection

With the upgrading of ISO standards and the standardization of OEM platforms, integrated protection is becoming a trend in automotive electronics.

The design concept of the JRN/JRT series is being widely adopted by the Tier-1 supply chain for applications such as BCMs, motor control modules, and smart seat systems. Within the next three years, integrated protection solutions are expected to replace more than 70% of traditional RC network designs.

8. Conclusion

The JRN/JRT series delivers three functions in one device—EMI suppression, surge clamping, and energy absorption.
With sub-25ns response and µF-level capacitance, it simplifies circuit design, reduces BOM cost, and guarantees compliance with ISO automotive standards.
For global Tier-1 and Tier-2 suppliers, this integration marks a key step toward smarter, faster, and safer automotive electronics.

Automotive EMC | EMI+Surge Integrated | JRN Series | DC Motor Protection | ISO 7637-2

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