Power over your Coax


Many smaller automotive electronic sub-systems receive their power from a coaxial cable.  This cable combines the power and data transmission to reduce the number of cables required.  This cable reduction decreases the extra weight and cost from the additional sub-system.  The numerous cameras appearing in new cars frequently use this “power over coax” scheme to deliver a few watts of power to the camera.

While the power sent over the coaxial cable is often protected from the battery’s extremely wide voltage excursions (3V to 60V, for example), a frequent challenge with power over coax is lesser voltage excursions produced by load changes and the subsequent voltage drop (IR drop) across the cable.  While the voltage at the Engine Control Unit (ECU) end of the cable might be regulated to 9V, the voltage at the camera end could be several volts different in either direction.  Supporting a wide input voltage range, such as 6V to 12V, and still delivering a well-regulated and low-noise output voltage is essential.

Since this camera sub-system is small and very low power, the power supply receiving the power over coax power should also be very small and highly integrated.  Due to the higher input voltage and small area available to dissipate heat, a linear regulator is not typically an option due to its low efficiency and high temperature rise at higher input voltages.

The new TPS62160-Q1, TPS62170-Q1 and TPS62172-Q1 fulfill this need.  These devices are very small, highly integrated, Q100 qualified, step-down converters supporting the wide input voltage range required for camera module applications.  Packaged in a 2-mm by 2-mm SON package and supporting a total solution size of less than 50 mm2, these devices convert a 3-V to 17-V input voltage down to a lower voltage rail to operate the entire sub-system. Over 90% efficiency keep the sub-system cooler--all the while making the best use of the limited power available.

What sub-systems are you powering with power over coax?