| ??? 08/04/12 00:56 Read: times |
#187993 - Same for ARM Responding to: ???'s previous message |
It started with multiple VCC voltages, but now many ARM chips too have internal DC/DC converters to allow the core to get a lower voltage internally while the external VCC controls the I/O signal levels. Alas, most ARM solutions are still 3V3 for external pins, making it much harder to get good overvoltage protection on ADC inputs without affecting linearity. And requiring sometimes more expensive MOS-FET transistors. Or sometimes requiring the I/O pin to switch between input and output, so it basically tri-states with a 5V pull-up.
Bigger chips normally have two VCC voltages because of the larger current needed to the core. But then the cost of the bigger chip is also a bit higher so extra cost of a separate voltage regulator doesn't matter as much. Requirements for an embedded Linux platform isn't the same as requirements for a design with basically just a single microcontroller and a bit of external glue. |
| Topic | Author | Date |
| CPLD level translators | 01/01/70 00:00 | |
| TI Voltage level translators ? | 01/01/70 00:00 | |
| thanks | 01/01/70 00:00 | |
| Why specifically CPLD? | 01/01/70 00:00 | |
| True | 01/01/70 00:00 | |
| Perhaps certain CPLD's would do the job | 01/01/70 00:00 | |
| Wide Vcc CPLDs sadly rare | 01/01/70 00:00 | |
| forgive my ignorance, but ... | 01/01/70 00:00 | |
| some examples | 01/01/70 00:00 | |
| Same for ARM | 01/01/70 00:00 | |
| some small devices have OCR too | 01/01/70 00:00 | |
| Bigger chips | 01/01/70 00:00 | |
Altera FPGAs | 01/01/70 00:00 |