1. Introduction
The CM8-001R is a miniature Surface Mount Device (SMD) common mode inductance choke designed for effective filtering of power and signal lines. It is particularly suited for Power over Ethernet (PoE) applications in LAN and Telecom systems, helping to suppress common mode noise and ensure signal integrity. This manual provides essential information for the proper use and integration of this component.
2. Specifications
The CM8-001R common mode choke offers robust performance for noise suppression in various applications. Key specifications are detailed below:
| Parameter | Value | Notes |
|---|---|---|
| Part Number | CM8-001R | |
| Type | Common Mode Inductor Filter | |
| Package | SMD (Surface Mount Device) | |
| Primary Inductance (DCL 100KHz 100mV) | 2.5mH (Min) | |
| Turns Ratio | 1:1 (±2%) | |
| DCR (Max) | 0.6 Ω | |
| LL 100KHz 100mV (Max) | 0.3 | |
| Isolation Voltage | 500VAC/1mA/60S (Min) | |
| Operating Temperature | -40°C to +85°C | |
| Storage Temperature | -25°C to +125°C | |
| Dimensions (L x W x H) | 6.6 mm x 6.2 mm x 5.5 mm (approx.) | Excluding pins |
| Compliance | IEEE 802.3af, FCC Class B, RoHS | |
| PoE Support | 250mA Max on 48Vdc | |
| Time to Live Isolation | 600ms | |
| Max Common Mode Attenuation | at 1MHz |
Impedance (KΩ MIN)
| Frequency | 100KHz | 400KHz | 500KHz | 800KHz | 1MHz | 2MHz |
|---|---|---|---|---|---|---|
| Impedance | 5 | 7 | 8 | 10 | 10 | 7 |
3. Setup and Installation
The CM8-001R is an SMD component and requires proper soldering techniques for installation onto a Printed Circuit Board (PCB). Ensure you have the necessary tools and expertise for SMD soldering.
3.1. Pin Configuration and Dimensions
The component features 8 pins (surfaces) for connection. Refer to the dimension diagram in Figure 2 for precise measurements and recommended PCB footprint design. The overall dimensions are approximately 6.6 mm x 6.2 mm x 5.5 mm.
3.2. Schematic Diagram
The internal schematic of the common mode choke is shown in Figure 2. It consists of two coupled inductors. Pins 2 and 3 form one winding, and pins 6 and 7 form the other. Ensure correct pin orientation and connection to your circuit for optimal performance.
3.3. Placement Considerations
- Proximity to Noise Source: Place the choke as close as possible to the noise source or the entry point of the power/signal line to be filtered.
- Grounding: Ensure proper grounding of the PCB to maximize the effectiveness of the common mode filtering.
- Thermal Management: While miniature, consider the operating temperature range (-40°C to +85°C) and ensure adequate thermal dissipation if the component is expected to carry significant current, especially in PoE applications.
4. Operating Principles
The CM8-001R functions as a passive common mode filter. When integrated into a circuit, it presents a high impedance to common mode currents (noise) while allowing differential mode signals (desired data/power) to pass through with minimal attenuation. This is crucial in applications like PoE where both power and data share the same lines, and common mode noise can degrade signal quality or interfere with other components.
In PoE applications, the choke is designed to support up to 250mA on 48Vdc lines, effectively filtering noise without significantly impacting power delivery or data transmission compliant with IEEE 802.3af standards.
5. Maintenance
As a passive electronic component, the CM8-001R common mode choke requires no routine maintenance. However, proper handling and storage are essential to ensure its longevity and performance.
- Handling: Avoid excessive mechanical stress or impact to the component.
- Storage: Store in a dry, temperature-controlled environment within the specified storage temperature range of -25°C to +125°C. Protect from static discharge.
- Cleaning: If cleaning the PCB, use appropriate electronic cleaning solutions and methods that do not damage the component or its connections.
6. Troubleshooting
If your circuit is not performing as expected after integrating the CM8-001R, consider the following troubleshooting steps:
- Verify Installation: Double-check all solder joints for proper connection and ensure there are no shorts or cold solder joints. Confirm correct pin orientation.
- Component Integrity: Use a multimeter to check for continuity across the windings (pins 2-3 and 6-7) and ensure there are no open circuits. Check for shorts between windings or to ground.
- Circuit Design: Review your PCB layout and schematic to ensure the choke is correctly integrated into the power/signal path as intended for common mode noise suppression.
- External Factors: Ensure that other components in the circuit are functioning correctly and that the power supply is stable and within specifications.
- Noise Source: If noise persists, investigate the source of the common mode noise. The choke's effectiveness depends on the characteristics of the noise and the overall circuit design.
7. User Tips
- Always use appropriate ESD (Electrostatic Discharge) precautions when handling electronic components to prevent damage.
- For optimal noise suppression, consider the impedance characteristics of the choke at the specific noise frequencies present in your application.
- When designing PCBs, ensure sufficient clearance and creepage distances for the component, especially in high-voltage or high-frequency applications, to maintain isolation.
8. Warranty and Support
For warranty information or technical support regarding the CM8-001R common mode inductance choke, please contact your point of purchase or the manufacturer directly. Ensure you have your purchase details and any relevant circuit diagrams available when seeking support.
