Power Manager II: How many I2C loads can I put on an I2C chain for Power Manager II devices?
When using the Power Manager-II; POWR1220AT8, POWR1014A or POWR6AT6, it is important to know the loading and driving source of the full set-up. In a case where there are just a few I2C loads, whether Lattice POWR devices or others, the designer needs to consider the capacitance that each of these hangs on the open drain signals SDA and SCL. As a general rule when using 6-8 devices or more, buffering may be needed. In the cases where there are just a few devices use 2.2k to 4.7k pull-ups to achieve a good rise-time and signals for each device. A quick scope check will assure you have good signals, don't forget the capacitance of the probe acts as a load too.