Hi Neil Just now, I disconnected TPS79333 from board and used LR6 battery for the analog part of TDC. The result does not show improvement. So I think LDO might not be the primary noise contributor.
Thanks for the suggestion. 2015-01-03 22:01 GMT+08:00 Neil Schroeder <gign...@gmail.com>: > I would reconsider the LDOs while you have some time to play with them. > The TPS79333DBVR is not even remotely "ultralow noise" at most offsets, > despite what TI may say. > > For 5V5 and under up to about 600ma, I would suggest you take a look at the > ADM7155 (adjustable) or ADM7154 (fixed). If you need 800ma, the 7150 is > here for you. > > > http://www.analog.com/en/power-management/linear-regulators/adm7155/products/product.html > > http://www.analog.com/en/power-management/linear-regulators/adm7150/products/product.html > > The TI part has nearly 35 uVRMS of noise at just 2.8a with not very good > PSRR. The 7155 will produce less than 1.0 μVRMS Total Integrated Noise > from 100 Hz to 100 KHz and 1.6 from 10 to 100 KHz,and that's without an RC > noise compensation network. Its a fabulous part for a sensitive > application like yours. > > I'm hoping I am right in assuming that the noise performance of the LDOs is > a concern, and don't mean to even dare suggest that you've done anything > but a great job! :-) > > NS _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.