User Manual
Using The TPA005D02 Class D EVM With the Plug-N-Play Platform
3-25
Details
3.3.4 Mute
The TPA005D02 class D EVM is equipped with a mute control input pin. When
this input is tied to GND, the TPA005D02 amplifier IC on the module enters the
mute mode and dissipates very little power. When the EVM control input is tied
to V
DD
or allowed to float, amplifier operation resumes.
In typical applications, as often found in notebook computers, portable audio
products, and such, the internal speakers mute when headphones are
plugged into the headphone jack, or internal speakers mute when external
speakers are connected. In applications using separate speaker and
headphone amplifiers, the one not being used can be muted to conserve
power.
3.3.4.1 Headphone Jack Control Signals
The platform headphone output jack (J10) contains an internal switch that
changes the state of a pair of control lines when a plug is inserted (Figure
3–19). Each control line is pulled down by a 1-kΩ resistor to ground (R4 and
R5). The switch in the headphone jack pulls one line or the other up to V
DD
through a 240-Ω resistor (R3) depending on whether a plug is inserted in J10
or not.
Figure 3–19. Mute/Mode and Polarity Control
J10
Headphone
Jack
R3
240 Ω
R4
1 kΩ
R5
1 kΩ
JP8 JP6
U2
Power
Amplifier
Lo
Hi
Polarity
Mode
Mute
V
DD
SPK
(U2–U4)
3.3.4.2 Mute/Mode Select (JP6)
A 3-pin jumper header (JP6) on the platform, functioning as an SPDT switch,
routes the control signal from the headphone jack to either the mute control
input pin or the mode control input pin of the evaluation module.
To mute the TPA005D02 class D EVM using the control signal from the
platform headphone jack, jumper JP6 to
MUTE.
To isolate the TPA005D02 class D EVM from the headphone jack
switch (since the TPA005D02 class D EVM has no mode control
input), jumper JP6 to
MODE.
3.3.4.3 Mute/Mode Polarity Select (JP8)
A second 3-pin jumper header (JP8) on the platform selects the control signal
polarity by connecting either the active-high or the active-low line from the
headphone jack to jumper JP6.
To mute the TPA005D02 class D EVM
when
a plug is inserted into the
headphone jack, jumper JP8 to
Lo
(the
Hi
position is NOT recommended).