Datasheet

24 TMC222 DATASHEET (V. 1.11 / Novermber 25, 2009)

5.3.3 Chopper Mechanism

The chopper frequency is fixed as specified in chapter 10.4 AC Parameters on page 46. The TMC222

uses an intelligent chopper algorithm to provide a smooth operation with low resonance. The TMC222

uses internal measurements to derive current flowing through coils. If the current is less than the

desired current, the TMC222 switches a H-bridge in a way that the current will increase. Otherwise if

the current is too high, the H-bridge will be switched to decrease the current. For decreasing two

modes are available, slow decay and fast decay, whereas fast decay decreases the current faster than

slow decay. The figure below shows the chopper behavior.

Figure 13: Different Chopper Cycles with Fast and Slow Decay