| ??? 07/25/06 14:54 Modified: 07/25/06 15:07 Read: times |
#121026 - ADC details? Responding to: ???'s previous message |
Prahald said:
The board uses ARM7 LPC2138 micro and there is no external ADC. I am using micros internal 10 bit ADCs. I tried to find any useful information about the built-in ADC, but, typical for Philips, the datasheet doesn't contain them! Do you have a link to details of ADC, about input resistance, input leakage current, equivalent input circuitry (dynamic loads, mulitplexing scheme), and, important, acquisition time? I wouldn't use a micro where only a preliminary datasheet exists!!! Can be your total ruin!! I have seen this... Prahald said:
Since I needed 4-20mA output that could even drive 600 Ohms loads I used 15V supply derived fron 7815 as analog section supply and 3.3V derived from LM1117-3.3 as digital section supply. To protect analog inputs of micro from accidental high voltage from analog section I used BAT54C schottkey diodes [ Clamp diodes to 3.3V]. In such applications it's useful to drive the ADC by an OPamp which is powered by the same power supply as the micro. Kai |
| Topic | Author | Date |
| Reistor in series in signal from Amp to ADC. | 01/01/70 00:00 | |
| You forgot the other Question | 01/01/70 00:00 | |
| Read the app notes | 01/01/70 00:00 | |
| What ADC? What application? | 01/01/70 00:00 | |
| Re: Application. | 01/01/70 00:00 | |
| That's not good | 01/01/70 00:00 | |
| a much more elaborate protection scheme must be im | 01/01/70 00:00 | |
| Re: RTD & high voltage output. | 01/01/70 00:00 | |
| what about a zener across the RTD? | 01/01/70 00:00 | |
| Some questions | 01/01/70 00:00 | |
| ADC details? | 01/01/70 00:00 | |
| datasheet does not contain because | 01/01/70 00:00 | |
| ADC details still missing! | 01/01/70 00:00 | |
| Yes ADC details Missing,. | 01/01/70 00:00 | |
| That's what we need the details for... | 01/01/70 00:00 | |
| what detail? | 01/01/70 00:00 | |
| Analog input circuitry and timing diagram | 01/01/70 00:00 | |
| Forum Power. | 01/01/70 00:00 | |
| Link? | 01/01/70 00:00 | |
| Re Link. | 01/01/70 00:00 | |
| if you use them, sign up | 01/01/70 00:00 | |
Thanks | 01/01/70 00:00 |