Texas Instruments SLOU121, Руководство пользователя

Страница: 34 / 42

Using the TPA6011A4 EVM With the Plug-N-Play Evaluation Platform
3-14 Details
output mode. When the mode control input is tied to GND, the module operates
in the BTL output mode. When this input is tied to V
DD
, the module operates
in the single-ended output mode.
In the typical application, output mode switching allows the TPA6011A4 to
operate in the BTL output mode for increased power to internal speakers and
then switch to single-ended mode to drive headphones when a plug is inserted
into the headphone jack.
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 (see
Figure 3–8). Each control line is pulled down by a 1-k
Ω
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 3–8. Mute/Mode and Polarity Control
J10
Headphone
Jack
R3
240
Ω
R4
1 k
Ω
R5
1 k
Ω
JP8 JP6
U2
Power
Amplifier
Lo
Hi
Polarity
Mode
Mute
VDD
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 shutdown
control input pin or the mode control input pin of the evaluation module.
-
To shut down the TPA6011A4 amplifier module using the control signal
from the platform headphone jack, jumper JP6 to MUTE.
-
To switch the output mode of the TPA6011A4 amplifier between BTL and
single-ended using the control signal from the platform headphone jack,
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.
-
When JP6 is set to mute, use the following JP8 settings for the
TPA6011A4:
J
To shut down the TPA6011A4 amplifier module when a plug is inserted
into the headphone jack, jumper JP8 to Lo (this is the typical setting).
J
To shut down the TPA6011A4 amplifier module until a plug is inserted
into the headphone jack, jumper JP8 to Hi.