18F8723 - 12 bit A/D

[Charles Linquis]

For anyone who needs a 12 bit A/D in a PIC, I have successfully used the new 18F8723. PBP doesn't explicitly support the chip, but if you compile for a 18F8722 and set "DEFINE ADC_BITS 10", the result from ADCIN is 12 bits. Even if you only need a 10 bit result, the new chip has lower jitter.
PBP2.47, PBP2.50 and PBPL2.50 all seem to work fine.

[Steve_88]

Thanks Charles for the info.

Where did you find this part?

Sample from MicroChip?

Sure would like to have a few of these around. You are quite pleased with the 12 bit performance?

-Steve

[Charles Linquis]

Yes, these were samples, but I have 100 pcs on order. Should have them any day now.

The A/D's on these parts are definitely less noisy. I plan on switching over to them 100% as soon as I run a few more tests.

[Steve_88]

Hi Charles,

Are you using an opamp to buffer and filter the input to the AtoD channels?
Thanks,
-Steve

[Charles Linquis]

No, I'm measuring power supply voltages, so my source impedance is low. I generally use a voltage divider with about a 2K source Z and a .1uF cap to the analog GND plane right at the PIC's analog input. I get good results. It also helps that I use a 0.1% low-noise Vref and average at least 6 samples.