LPF-01 - LC Common Mode Power Filter

Update March 2013: It is now possible to select between common mode and single mode filtering. A solder jumper pad on the input side disables filtering on the negative/ground-lead. If you experience issue with OSD systems, try changing the filter to single mode.

This is a compact and effective LC filter designed to clean a noisy DC power supply. Perfect for sensitive FPV- and RC-components in a single battery setup. The filter has properties to reduce the effects of interference radiated through the air and noise conducted via the power wires. One advantage of this filter is that both the negative and positive leads are filtered (common mode).

Suitable for setups up to 16V and maximum 1.5A (1500mA) load. The 3-pin input allows for a single bypass-signal. Custom configuration of leads length and connectors are available.

Problems often occur on sensitive FPV video systems when long power leads (15cm+) are used, limited space for wiring, improperly filtered transmitters, noise from speed controller or switch mode DC-DC voltage converter, or most commonly a shared battery is used to minimize weight. The interference can result in video lines, banding, random drop-outs, and reduced transmission range. A low-pass LC-filter will help attenuation most of the high frequency power supply noise and interference.

A common-mode choke coil is used to provide large impedance (resistance) against common-mode current noise picked up by both power leads. It is more effective for noise suppression than conventional ferrite ring and differential-mode inductor setups. This means that noise coming in on both wires will canceled each other out leaving only the regular differential-mode current flowing through the choke.

The large series inductor will give good current noise suppression between the input and output. Low resistance of the coils cause only minimum voltage drop over the filter (<200mV) and the low-ESR capacitor used will ensure efficient ripple voltage (noise) reduction (<120mVpk-pk).

Only known brand and quality parts are used to offer the great filtering properties. Every filter is tested before being shipped out.

Specifications

• Revision: Rev3 March 2013
• Type: passive common-mode low-pass power ripple filter
• Modes: common mode, single mode - jumper selectable
• Maximum voltage: 16V DC
• Maximum current: ~1.5A
• Cutoff frequency at -3dB: 127 Hz (attenuates higher frequencies/noise)
• Voltage drop over filter: 180mV at 900mA
• Maximum voltage ripple: 120mV
• Capacitor: Japanese Polymer Capacitor
  • Impedance/ESR: 0.012 Ohm at 100kHz/16V
  • Ripple current: 5000mA rms
• Choke: German Common-mode Choke
  • Series resistance (DC): 0.205 Ohm/path
• Wire / trace thickness: twisted 22 AWG / 32 mils
• Operating temperature: -40 °C to +105 °C
• Dimensions: 37.7 L x 8.8 W x 14.5 H mm
• Weight: 8.1 grams (inc. JST connectors)
• RoHS compliant
• Designed and made in Europe