In general, the I2C bus and SMBus are compatible, but there are some subtle differences between the two that could cause some problems. The following tables summarize the differences between the two buses.
| SMBus | ||
|---|---|---|
| Minimum | none | 10 kHz |
| Maximum | 100 kHz (Standard mode) 400 kHz (Fast mode) 2 MHz (High Speed mode) |
100 kHz |
| Timeout | none | 35 ms |
Electrical Characteristics Comparison
| SMBus | ||
|---|---|---|
| VHIGH | Fixed Voltage: 3.0 to VDD_max + 0.5V VDD Relative: 0.7 to VDD_max + 0.5V |
2.1V to VDD |
| VLOW | Fixed Voltage: -0.5V to 1.5V VDD Relative: -0.5 to 0.3VDD |
to 0.8V |
| Max Current | 3 mA | 350 µA |
For more detailed information, check out: