
MODES OF OPERATION
Mux Output Mode
Differential Input Mode
START-UP SEQUENCING AND SHUTDOWN CONTROL
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The TPA2054D4 has several operating modes for single-ended and differential inputs. Stereo 1 refers to the
LIN_1 and RIN_1 input pair; Stereo 2 refers to the LIN_2 and RIN_2 input pair.
The input mux selects which device input is directed to both the Class-D and headphone amplifiers. Mux
summing and output are after the channel volume controls, as shown in the Simplified Functional Diagram.
Program the mux mode using the Mode[2:0] bits in Mux Output Control (Register 3, Bits 0–2). Select the
appropriate mode according to the table below.
MODE
MUX OUTPUT
BYTE:
MUX MODE
MUX OUTPUT DESCRIPTION
LEFT
RIGHT
MODE[2:0]
000
Mono Input
Mono+ – Mono-
Differential mono input
001
Stereo 1 Input
LIN_1
RIN_1
LIN_1 and RIN_1 stereo single-ended input
010
Stereo 2 Input
LIN_2
RIN_2
LIN_2 and RIN_2 stereo single-ended input
LIN_1 and RIN_1 compose the left channel; LIN_2 and
011
Stereo Differential
LIN_1–RIN_1
LIN_2–RIN_2
RIN_2 compose the right channel
Stereo Differential
(LIN_1–RIN_1) +
Left and right differential inputs summed and directed to
100
(mono-mode)
(LIN_2–RIN_2)
left and right mux output
Stereo 1
LIN_1 + RIN_1 distributed to both left and right inputs of
101
LIN_1 + RIN_1
(mono-mode)
the headphone and Class-D amplifiers
Stereo 2
LIN_2 + RIN_2 distributed to both left and right inputs of
110
LIN_2 + RIN_2
(mono-mode)
the headphone and Class-D amplifiers
111
Mute
All inputs muted; no audio available at mux output
The LIN_1 and RIN_1 input pair and the LIN_2 and RIN_2 input pair are configurable as either single-ended or
differential inputs. Differential transmission between an audio source and the TPA2054D4 input improves system
noise rejection when compared to single-ended transmission.
In differential input modes, connect the Left+ and Left– source signal to LIN_1 and RIN_1, respectively; connect
Right+ and Right– to LIN_2 and RIN_2, respectively. Single-ended input modes allow selection between two
stereo sources. Differential input modes allow connection to only one stereo source.
For correct start up with no turn-on pop, apply PVDD and VDDHP before applying DVDD while keeping RESET
at logic low. Once DVDD has settled to a minimum of 1.7 V, set RESET to logic high to complete the start-up
sequence. The TPA2054D4 starts up in soft shutdown mode with the SWS bit (Register 2, Bit 4) at logic high.
The stereo Class-D power amplifiers, left headphone amplifier, and right headphone amplifier each have their
own enable bits within the Power Management byte (Register 2, Bits 3–1). Set the corresponding bit to logic high
to enable these amplifiers. Disabling an amplifier mutes its output and reduces supply current. Set SWS to logic
high to deactivate all sections except the I2C interface, reducing total supply current to 2
A, max.
Set RESET to logic low to deactivate all sections including the I2C interface. The I2C registers cannot be
programmed while RESET remains at logic low. Refer to the Headphone Output Limiter Lockout section for more
details on using RESET.
All register contents are maintained provided the supply voltage is not powered down and RESET remains at
logic high. On deactivation of DVDD or PVDD, or on RESET set to logic low, all information programmed into the
registers by the user is lost, returning to their default state once power is reapplied.
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Copyright 2009, Texas Instruments Incorporated