Datasheet

TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.03 • 2018-Sept-06
49 / 158
4.9.1 Biquad Filters
The TMC4671 uses standard biquad filters (standard IIR filter of second order) in the following structure.
Y(n) = X(n) · b_0 + X(n-1) · b_1 + X(n-2) · b_2 + Y(n-1) · a_1 + Y(n-2) · a_2 (24)
In this equation X(n) is the actual input sample, while Y(n-1) is the filter output of the last cycle. All
coefficients are S32 values and are normalized to a Q3.29 format. Users must take care of correct
parametrization of the filter. There is no built-in plausibility or stability check. All filters can be disabled or
enabled via register access. Biquad state variables are reset when parameters are changed. The TRINAMIC
IDE supports parametrization with wizards.
A standard biquad filter has the following transfer function in the Laplace-Domain:
G(s) =
b_2_cont · s
2
+ b_1_cont · s + b_0_cont
a_2_cont · s
2
+ a_1_cont · s + a_0_cont
(25)
©2018 TRINAMIC Motion Control GmbH & Co. KG, Hamburg, Germany
Terms of delivery and rights to technical change reserved.
Download newest version at www.trinamic.com