1/2 TC2001
Tripath Technology, Inc. - Technical Information
V5
RFBA
Processing
&
M o d u la tio n
FBKOUT1 28
FBKGND1 27
RFBB
RFBA
RFBC
RFBC
RFBB
OUT1
OUT1 GROUND
AGND
Figure 3: Modulator Feedback
The modulator feedback resistors are:
RFBA = User specified, typically 1K Ω
R FBB = RFBA * VPP
(VPP - 4)
R FBC = R FBA * VPP
4
A V - MODULATOR ≈ R FBC * (R FBA + R FBB ) + 1
R FBA * R FBB
The above equations assume that VPP=|VNN|.
For example, in a system with VPPMAX=40V and VNNMAX=-40V,
RFBA = 1kΩ, 1%
RFBB = 1.097kΩ, use 1.1kΩ, 1%
RFBC = 10.0kΩ, use 10.0kΩ, 1%
The resultant modulator gain is:
AV - MODULATOR ≈ 10.0k Ω * (1.0k Ω + 1.1k Ω ) + 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