# SMBus: Is 100 kHz clock a risky frequency?

I will communicate with a device via SMBus. I use PIC18F26K83 for this. In SMBus spec it says clock minimum clock frequency is 10 kHz and maximum clock frequency is 100 kHz. Would it be a risk to use 100 kHz clock frequency since it is the boundary and max limit? Or is it safer to go with 75 kHz for example?

I will be using multiplexer and communicating with 3 smart batteries. Reading their SOC and send these data with UART to another PIC. Cable length from batteries to PIC will not be more than 1 meter long. I am planning to make MCU clock also 100 kHz.

• Operating at $100\:\text{kHz}$ is usually okay. Of course, details matter. But generally, it's not risky. We'd need more details about the context and specific details to offer more, I think. – jonk Mar 27 '19 at 7:06
• Okay so I will be using multiplexer and communicating with 3 smart batteries. Reading their SOC and send these data with UART to another PIC. Cable length from batteries to PIC will not be more than 1 meter long. I am planning to make MCU clock also 100 kHz. – Günkut Ağabeyoğlu Mar 27 '19 at 7:19
• Cable capacitance is a considerable issue with I2C, SMBus, etc.. If you are connecting the devices with a 1m long cable you should mention that on your question and not on the comments.. – Wesley Lee Mar 27 '19 at 7:24
• from my understanding, generally 100KHz is defacto standard for most i2c chips and it would work with it without problems (or actually designed to work with it)?. – Hasan alattar Mar 27 '19 at 7:31