Texas Instruments TPA3003D2 - Manual (Page 21)

TPA3003D2
SLOS406A − FEBRUARY 2003 − REVISED MARCH 2003
21
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APPLICATION INFORMATION
GND
SD = 0 V
Figure 28. Differential Output With FADE Terminal Held High
MUTE operation
The MUTE pin is an input for controlling the output state of the TPA3003D2. A logic high on this pin disables
the outputs. A logic low on this pin enables the outputs. This pin may be used as a quick disable or enable of
the outputs without a volume fade. Quiescent current is listed in the dc characteristics specification table. The
MUTE pin should never be left floating.
For power conservation, the SD pin should be used to reduce the quiescent current to the absolute minimum
level. The volume will fade, slowly increase or decrease, when leaving or entering the shutdown state if the
FADE terminal is held low. If the FADE terminal is held high, the outputs will transition very quickly. Refer to the
FADE operation section.
SD operation
The TPA3003D2 employs a shutdown mode of operation designed to reduce supply current (I
CC
) to the absolute
minimum level during periods of nonuse for power conservation. The SD input terminal should be held high (see
specification table for trip point)during normal operation when the amplifier is in use. Pulling SD low causes the
outputs to mute and the amplifier to enter a low-current state. SD should never be left unconnected, because
amplifier operation would be unpredictable.
For the best power-off pop performance, the amplifier should be placed in the shutdown mode prior to removing
the power supply voltage.
selection of COSC and ROSC
The switching frequency is determined using the values of the components connected to ROSC (pin 20) and
COSC (pin 21) and may be calculated with the following equation:
f
OSC
= 6.6 / (R
OSC
* C
OSC
)
The frequency may be varied from 225 kHz to 275 kHz by adjusting the values chosen for R
OSC
and C
OSC
.
The recommended values are C
OSC
= 220 pF, R
OSC
=120 k
Ω
for a switching frequency of 250 kHz.