| ??? 07/16/06 16:42 Read: times |
#120336 - AD7798 with 89S52 - ADC failure |
AD7798 ADC( 16 bit ADC -Analog devices) was used with Atmel 89S52. Inteface as follows
5V LDO (Micrel make) – 10 uF tantalum and 0.1 uf mlc at output - Vout Vout is given to analog Vcc of ADC through a ferrite bead and a 0.1uF mlc to GND- Va Vout is also given to uC and display circuit through 27ohms and ferrite bead and 0.1 uF mlc – Vdd Va is given to the digital supply of ADC through a ferrite bead and 0.1 uF mlc. We made some pcbs and tested. Initially they were all ok but 25% of them failed within a day. Others continue to work ( now about 3 weeks). After carefull analysis I could make out perhaps one grey area – ie. uC supply is less than that of the ADC. Can it do any harm. Or have I missed any thing ? dileep shenoy |
| Topic | Author | Date |
| AD7798 with 89S52 - ADC failure | 01/01/70 00:00 | |
| Draw it | 01/01/70 00:00 | |
| Input Protection. | 01/01/70 00:00 | |
| LDOs are prone to oscillate! | 01/01/70 00:00 | |
| ADC failure | 01/01/70 00:00 | |
| what do you have on the ports | 01/01/70 00:00 | |
| Nature of the failure? | 01/01/70 00:00 | |
Nature of failure | 01/01/70 00:00 |