Tripath Technology, Inc. – Preliminary Technical Information
V+
Y
LC filter
L
C
Power
Stage
TCD6001
V+
LC filter
L
C
YB
FBP
FBN
R3
R3
R2
R2
Figure 3 - Feedback network for bridged configurations (1 channel shown)
In bridged configurations like the one shown in Figure 3, R1 is absent (infinity). Since the feedback is now
bridged, the feedback voltage should be cut in half to 2Vpp.
To solve for the values of the feedback resistors in a bridged configuration:
R2 = User specified, typically 1KΩ
25K * R2 VPP - 2
R3 =
*
25K + R 2
2
For example, in a system with VPPMAX=20V,
R2 = 1kΩ, 1%
R3 = 8.654kΩ, use 8.66kΩ, 1%
VCLAMP BIASING
The VCLAMP pins must have DC voltages applied which are proportional to the peak to peak voltage
swings of the power output switching stages in the amplifier system. More explicitly, the potential at the
VCLAMP pins should be 0.525 times the peak to peak differential voltage seen at each channel's feedback
pins (i.e., the full final value voltage swing neglecting any RC settling time effects). This means that the
component values used in the circuitry biasing the VCLAMP pins are direct functions of the chosen feedback
network components.
There are two VCLAMP pins: VCLAMP_SE and VCLAMP_BR. When the SE/BRGB pin is high, the
VCLAMP_SE voltage is used and the VCLAMP_BR voltage is ignored. When the SE/BRGB pin is low, the
VCLAMP_BR voltage is used and the VCLAMP_SE voltage is ignored. In a full bridged system, proper
VCLAMP_BR biasing is achieved via a simple two resistor divider between V+ (the output stage power
supply) and ground, shown in the right-hand portion of the circuit below (excluding the portion in the dotted
line box). In a single ended (half bridge) system, VCLAMP_SE biasing is achieved by the entire six element
circuit below.
39
TCD6001 – JL/Rev. 0.9/07.05
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
