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Kieran McDonald

Field Applications Systems Engineer
Kieran McDonald has worked in the electronics and semiconductor industry for 16 years with 13 of those years as a Field Application Systems Engineer at ON Semiconductor. Based near Cambridge, UK, his work is focused in the area of automotive systems, about which he has published numerous articles. Kieran holds an MSc Advanced Microelectronics degree from the University of Bolton, UK.

Swimming Upstream! Considerations in Automotive Upstream Point-of-Load Conversion 

by Kieran McDonald - 2015-07-08 09:31:50.0

Many automotive power supply architectures require upstream point-of-load (POL) conversion, particularly Advanced/Autonomous Driver Assistance Systems (ADAS) applications where the low core voltage of many System-On-Chips (SoC) and Digital Signal Processors (DSP) are beyond todays Switched Mode Power Supply’s (SMPS) maximum conversion ratio or main switch minimum off-time capability.  POL conversion typically involves down conversion from a primary, battery connected rail voltage to a lower secondary voltage rail required by a particular load.  Other application and load dependent attributes may be required too, such as low noise, high PSRR or high levels of load transient response.  However, adding secondary power supplies upstream of the battery connected primary converter can lead to issues.




The Dilemmas of Free-Wheeling: Choosing a Schottky Rectifier for an Automotive Synchronous Converter 

by Kieran McDonald - 2015-04-06 14:50:44.0

For many low and medium power rails, within a given automotive system, the asynchronous buck converter remains the optimum compromise between cost and efficiency.  Implied and critical to this approach is the choice of buck diode.  Despite this, pondering the diode doesn’t pre-occupy many, yet the wrong choice can lead to low efficiency, high power dissipation and high electro-magnetic emissions (EME) or worse!




Cranky on a Cold Day! Guaranteeing Automotive System Minimum Input Volts 

by Kieran McDonald - 2014-12-16 10:34:52.0

The normal voltage level of what is designated as a 12 V vehicle lead acid battery may vary between 9 V and 16 V.  However, subject to extreme cold temperatures, the battery voltage level when the starter is engaged can be as low as 3.0 V, a condition that might last for as long as 19 mS.   The conventional vehicle power supply architecture can be adapted to guarantee vehicle system operation through such conditions.  

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