re ??1232:

On an older design, still produced, with 10.000+ in the field we have had problems with the 1232.

All problems are gone when a 100nF capacitor is soldered DIRECTLY across Vcc and Gnd on the chip.

The (no adjective - would be rude) person that laid out the original board allowed 1"+ traces from the chip to the decoupling capacitor and many of those boards require that we solder a cap atop the 1232 (of course, we do it on all of them when they show up).

Without the added capacitor (a rough measurement of noise suspectability) we have tried various 1232s and found that the worst is Microchip and the best is MAX. Today we use only the MAX and have a new layout of the board that put the decoupling caps right at the chips.

Erik