TCA2002 Datasheet, PDF (13/18 Pages) Tripath Technology Inc. – STEREO CLASS-T™ AUDIO CONTROLLER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology, Inc. - Technical Information
Figure 5 shows the basic single supply, bridged output amplifier using a TCA2002. The MOSFET
output stage operates from a single power supply, VPP (for instance 60VDC). Both terminals of the
speaker are actively driven. Differential feedback is taken from each half-bridge output. The resistor
divider networks at the TCA2002 scale the feedback signals. The resistor values are determined
based on the supply voltage, as explained below.
It should be noted that only one channel of the modulator is required to create a bridged amplifier.
This is done by reversing the Y1 and Y1B connections to the second FET driver. This creates an out
of phase signal at HB OUTN with respect to HB OUTP.
A bridged amplifier has the advantage of potentially 4 times the output power for a given supply rail.
But the disadvantage is that the required number of FET drivers and MOSFETs per channel
increases by a factor of two.
The modulator feedback resistors are:
RFBB = User specified, typically 1K Ω
R FBC = 350 * VPP − 1000
R FBB = ^{2333.33 * R FBC}
(1000 + RFBC )
AV - MODULATOR ≈ ^{R FBC * (R FBA + R FBB )} + 1
R FBA * R FBB
For example, in a system with a SINGLE-SUPPLY, BRIDGED OUTPUT amplifier of VPP_MAX = 60V,
R_FBA = 2.22kΩ, use 2.21kΩ, 1%
R_FBB = 1kΩ, 1%
R_FBC = 20kΩ, 1%
The resultant modulator gain is:
AV - MODULATOR ≈ ^{20.0k Ω * (1.0k Ω + 2.21k Ω )} + 1 = 30.05V/V
1.0k Ω * 2.21k Ω
Mute Control
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 are fully
operational. Please note, that unlike previous Tripath controllers such as TC2000 and TC2001, the
state of MUTE does not effect the input stage biasing. Thus, even if MUTE is high, the bias at INV1
will be active. This will keep the input capacitor, C_I, charged via R_I, thus, minimizing turn-on pops.
Please note that the TCA2002 requires about 250mS to become active, after the de-assertion of
MUTE (MUTE logic high MUTE logic low). Also, the TCA2002 requires about 350uS to go into
mute, after the assertion of MUTE (MUTE logic low logic high).
Break-Before-Make (BBM) Timing Control
The TCA2002 can also insert a delay between the Yx and YxB output signals. This dead time will
minimize shoot thru currents, in the case that the output driver or power stage does not have built in
BBM circuitry. BBM0 and BBM1 are logic inputs (connected to logic high or pulled down to logic low)
that control the break-before-make timing of the output transistors according to the following table.
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TCA2002 – KLi/0.95/04.06