TCA2002 Datasheet, PDF (14/18 Pages) Tripath Technology Inc. – STEREO CLASS-T™ AUDIO CONTROLLER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology, Inc. - Technical Information
BBM1
0
0
1
1
BBM0
0
1
0
1
Delay
120 ns
80 ns
40 ns
0 ns
Table 1: BBM Delay
The tradeoff involved in making this setting is that as the delay is reduced, distortion levels improve
but shoot-through and power dissipation increase. The actual amount of BBM required is dependent
upon components such as MOSFET type and gate resistor value as well as circuit board layout. The
BBM value selected should be verified in the actual application circuit board. It should also be verified
under maximum temperature and power conditions since shoot-through in the output MOSFETs can
increase under these conditions, possibly requiring a higher BBM setting than at room temperature.
The voltage at the BBM pins is sampled at the falling edge of mute. Thus, the BBM cannot be
dynamically adjusted based on the output level of the amplifier.
Output Voltage Offset
The TCA2002 does not have internal compensation for DC offset. The circuit shown in the Typical
Application circuit is a simple passive circuit that covers the range of expected offset voltage. Tripath
has had success with both active and passive circuits for this purpose; please consult with the Tripath
Applications team for further information.
HMUTE
The HMUTE pin is a 5V logic output that indicates various fault conditions within the device. Also,
HMUTE will be high if the MUTE input is connected to a logic high level.
OVRLDB
The OVRLDB pin is a 5V logic output that is asserted just at the onset of clipping. When low, it
indicates that the level of the input signal has overloaded the amplifier resulting in increased distortion
at the output. The OVRLDB signal can be used to control a distortion indicator light or LED through a
simple buffer circuit, as the OVRLDB cannot drive an LED directly. There is a 20K resistor on chip in
series with the OVRLDB output.
If only 1 channel of the TCA2002 is used, the OVERLDB pin will be permanently low, since one
modulator will not be switching. This can be alleviated if the unused (not connected to a power stage)
modulator is run in self-feedback mode, via a few external resistors. Please contact your local sales
office for more information.
Over-current Protection
The TCA2002 has two over-current protection comparator inputs, located at OCD1 and OCD2.
These inputs can be connected to an external power stage, over current circuit output, such as that of
TP2150B or similar.
When the voltage across R_OCR becomes greater than V_TOC (approximately 0.97V) the TCA2002 will
mute. Please note that the voltage at a given OCDx pin will need to exceed V_TOC for 3uS for the fault
to register. The low pass filter formed by ROCR and COCR further enhances this time-based
deglitching. Upon an over-current fault, the HMUTE signal will be pulled high and both Yx and YxB
will be low. Please note that both channels are muted if an over-current condition occurs.
The reaction to an over-current fault is different than previous Tripath controllers. Unlike previous
controllers that latched an over-current fault, the TCA2002 will automatically try to recover. Once an
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TCA2002 – KLi/0.95/04.06