Power supply for electrochromic mirrors in high voltage automotive power systems

A vehicular electrical system, comprising:

• a power supply configured to receive power from a vehicle power source having a voltage in excess of about 24 volts, said power supply is further configured to supply power to at least one electrically operated rearview mirror element and at least one electrically powered device at a voltage less than said power source voltage, said electrical system exhibiting an electromagnetic interference level less than about 47.8 dBμV/m for emissions in the frequency range from about 0.4 MHz to about 1000 MHz, wherein said at least one electrically powered device is selected from the group comprising:
• a light-emitting diode, a break light, a center high-mounted stop lamp, a cargo light, a turn signal indicator assembly, a cellular telephone transceiver, a trainable transceiver, a user activated switch, a tire pressure monitoring system, a GPS receiver, a compass, a display, a vehicle bus interface and a light sensor.

A vehicular electrical system, comprising:

• a power supply configured to receive power from a vehicle power source having a voltage in excess of about 24 volts, said power supply is further configured to supply power to at least one electrically operated rearview mirror element and at least one electrically powered device at a voltage less than said power source voltage, said electrical system exhibiting an electromagnetic interference level less than about 28 dBμV/m for narrowband emissions in the AM broadcast band.

A vehicular electrical system, comprising:

• a power supply configured to receive power from a vehicle power source having a voltage, said power supply is further configured to supply power to at least one electrically powered device at a voltage less than said power source voltage, said electrical system exhibiting an electromagnetic interference level less than about 47.8 dBμV/m for emissions in the frequency range from about 0.4 MHz to about 1000 MHz;
• and
• circuitry for dithering the pulse width or the switching frequency of said power supply.