Tripath Technology, Inc. - Technical Information
1/2 TC2001
V5
RFBA
RFBA
RFBC
FBKOUT1
Processing
&
Modulation
28
27
OUT1
FBKGND1
OUT1 GROUND
RFBC
RFBB
RFBB
AGND
Figure 3: Modulator Feedback
The modulator feedback resistors are:
R
R
FBA = User specified, typically 1KΩ
R
FBA * VPP
FBB
=
(VPP - 4)
R
FBA * VPP
R
A
FBC
=
4
R
FBC * (RFBA + RFBB )
V - MODULATOR
≈
+ 1
R
FBA * RFBB
The above equations assume that VPP=|VNN|.
For example, in a system with VPPMAX=40V and VNNMAX=-40V,
RFBA = 1kΩ, 1%
R
FBB = 1.097kΩ, use 1.1kΩ, 1%
RFBC = 10.0kΩ, use 10.0kΩ, 1%
The resultant modulator gain is:
10.0k Ω * (1.0k Ω + 1.1k Ω)
A
V - MODULATOR
≈
+ 1 = 20.09V/V
1.0k Ω * 1.1k Ω
Mute
When a logic high signal is supplied to MUTE, both amplifier channels are muted (both high- and
low-side transistors are turned off). When a logic level low is supplied to MUTE, both amplifiers
20
TK2150 – Rev. 1.0/12.02
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