Tri p ath Techn o l o g y, I n c. - T echn i cal I n fo rmation

14

TCA2002 – KLi/0.95/04.06

BBM1

BBM0

Delay

0

0

120 ns

0

1

80 ns

1

0

40 ns

1

1

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.

Ou tpu t Voltag e 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.

O v er-c urrent Prote c t ion

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.

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