April 15 2016
This is my candidate to replace the PicoLynx power converter module: The TI TPS62143RGTR (Digikey 296-39448-1-ND) IC REG BUCK 5V 2A SYNC 16QFN, 10 for $2.162 each, 100 for $1.7345 each. The description looks good: input 3-17V, output 0.9-6V, continuous current 2A. The TPS62143 is the non-adjustable 5V version, the TPS62142 is 3.3V, the TPS62141 is 1.8V, and the TPS62140 is the adjustable version. This will require adding an external coil, but not much more.
9.2.2.1 Programming the Output Voltage
While the output voltage of the TPS62140 (TPS62140A) is adjustable, the TPS62141/2/3 are programmed to fixed output voltages. For fixed output versions, the FB pin is pulled down internally and may be left floating. It is recommended to connect to AGND to improve thermal resistance.
So I omit the two resistors and leave FB as no-connect.
The recommended coil is not available from Digikey. The 3.1A rating is overkill for this board, I think 1A would be plenty. The cheap option is the Bourns SRR1005-2R2M FIXED IND 2.2UH 3.1A 27 MOHM SMD (Digikey SRR1005-2R2MCT-ND) at 10 for $0.81 each, 100 for $0.6156.
This puts the cost of the power converter at about 10 for $3.50 each, 100 for $2.35 each. This cuts about a $1.00 from each board compared to the PicoLynx.
Hey, wait a minute... I already have a 2.2uH coil in the BOM. The NR3010T2R2M is rated for 1.1A, which is plenty. I can use this part and save even more money!
Creating the TPS62143 component from scratch. I learned a new DipTrace trick to place two vertical rows of pins and number them correctly. I want pin 1 to be at the top left, pin 16 at the top right. DipTrace/Component doesn't let me renumber the pins like the Pattern editor, instead always numbering them from the bottom up. The trick is to place the left-side row first, do a vertical flip, then place the right-side row.
The single biggest lacking feature in DipTrace is a simple "Align" button.
Here is the redesigned 12 to 5VDC converter. It took about hour and a half, including all the research into the TPS62143.
Woot! I spent another hour removing the old components and adding the new ones. This power converter is much cheaper than the PicoLynx! The per-100 board cost is back under $30. I was also able to reduce the BOM by 4 parts.