TCD6000 Datasheet, PDF (32/36 Pages) Tripath Technology Inc. – 6 CHANNEL CLASS-T DIGITAL AUDIO PROCESSOR USING DIGITAL POWER PROCESSINGTM TECHNOLOGY

FEEDBACK CONNECTIONS
V+
Y
TCD6000
YB
FBN
FBP
5V
V-
R1
R1
R3
R3
R2
R2
Tripath Technology, Inc. – Preliminary Technical Information
LC filter
L
C
Figure 2 - Feedback network for single ended configurations (1 channel shown)
Differential feedback from the power stage outputs to the TCD6000 FB inputs is required. This feedback is
taken directly from the outputs of the power stage, before the LC filter stage. It allows the TCD6000 to
compensate for power stage distortion (non-linearity, power supply noise, etc.) and to deliver an ultra-low
THD that is unique to class-T technology. Total harmonic distortion is typically less than 0.03% with most
power stages.
Resistors R1, R2, and R3 create a voltage divider structure to reduce the unfiltered output of the power
stage for the feedback pins. In single ended output configurations like the one shown in Figure 2, the
feedback voltage should be approximately 4Vpp. R1 and R2 bias the feedback signal to approximately 2.5V
and R3 scales the large output voltages down to 4Vpp. The input impedance of the TCD6000 feedback pins
is approximately 25K.
To solve for the values of the feedback resistors in a single ended configuration:
R1 = User specified, typically 1K Ω
R2
=
(VPP
R1 * VPP
-
4
-
VPP *
25K
R1
)
R3
=
R1 * VPP
4
The above equations assume that VPP = |VNN|.
For example, in a system with VPP_MAX = +28V and VNN_MAX = -28V,
R1 = 1kΩ, 1%
R2 = 1.224kΩ, use 1.21kΩ, 1%
R3 = 7.00kΩ, use 6.98kΩ, 1%
32
TCD6000 – Rev. 1.0/09.04