## Tuesday, May 8, 2012

### What is the difference between Bit Rate and Baud Rate in Power Supply Remote Communications?

Many modern power supplies, such as TDK-Lambda's new Z+ programmable supplies and the HFE series of rack mount supplies, now feature serial data interfaces such as I2C, USB 2.0, and RS485, to name a few. The transmission rates of these serial data interfaces are specified as bits-per-second (bits/s) and/or baud rate. As a refresher, here is a brief review of the difference between Bit rates and Baud rates.

The Bit rate is the number of bits (binary zeros and ones) that are transmitted during one second (bits/s). The Baud rate refers to the number of signal units (symbols or characters) that are transmitted per second.

Equation for Baud Rate:
baud rate = bit rate (bits/s) ÷ N, where N is the number of bits represented by each signal shift (symbol or character).
For example, if the bit rate is 9,600 bits/s and the communications format require 8 bits per symbol, the baud rate would be 9,600 bits/s divided by 8 bits, which would equal 1200 baud.

Equation for Bit Rate:
Bits/s = baud per second x the number of bits per symbol
Therefore, from the above example:
Bits/s = 1200 baud x 8 bits = 9,600 bits/s