TFA9812HN PHILIPS [NXP Semiconductors], TFA9812HN Datasheet - Page 8

• Manufacturer Part Number: TFA9812HN
• Description: BTL stereo Class-D audio amplifier with I2S input
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
8. Functional description
TFA9812_2
Preliminary data sheet
8.1 General
Table 3.
The TFA9812 is a high-efficiency stereo BTL Class-D amplifier with a digital I
input. It supports all commonly used I
Figure 1
TFA9812. In the digital domain the audio signal is processed and converted to a pulse
width modulated signal using BD modulation. A BTL configured power comparator carries
out power amplification.
The audio signal processing path is as follows:
Pin
47
48
Exposed
die-paddle
1. The Digital Audio Input (DAI) block translates the I
2. The 10-band parametric equalizer can optionally equalize the stereo audio stream.
3. Volume control in the TFA9812 is done by attenuation. The attenuation depends on
4. The interpolation filter interpolates from 1 fs to the PWM controller sample rate
5. The gain block can boost the signal with 0 dB or +24 dB. Four specific gain settings
6. The power limiter limits the maximum output signal of the TFA9812. The power limiter
7. The PWM controller block transforms the audio signal into a BD-modulated PWM
8. Via four differential comparators the PWM signals are amplified by two BTL power
standard internal stereo audio stream.
Both channels have separate equalization streams. It can be used for speaker transfer
curve compensation to optimize the audio performance of applied speakers.
the volume control settings and the thermal foldback value. Soft mute is also arranged
at this part. In Legacy mode the volume control is done by an on-board
Analog-to-Digital Converter (ADC) which measures the analog voltage on pin 32.
(2048 fs at 44.1 kHz) by cascading FIR filters.
are also provided in this block. These specific gain settings are related to maximum
clip levels of < 0.5 %, 10 %, 20 % or 30 % THD at the TFA9812 output. These
maximum clip levels are only valid with the gain boost set to 0 dB and a 0 dBFS input
signal.
settings are 0 dB, 1.5 dB, 3 dB, and 4.5 dB. This function can be used to reduce
the maximum output power delivered to the speakers at a fixed supply voltage and
speaker impedance.
signal. The BD-modulation provides a high signal-to-noise performance and
eliminates clock jitter noise.
output stages. By default the left audio signal is connected to channel 1 and the right
audio signal to channel 2.
shows the functional block diagram, which includes the key function blocks of the
Pinning description TFA9812
Symbol
MCLK
V
-
SS2
Rev. 02 — 22 January 2009
Type Description
I/O
P
P
Master clock input (I
mode)
PCB ground reference
PCB ground reference
BTL stereo Class-D audio amplifier with I
2
S formats.
…continued
2
S slave mode) or output (I
2
S (-like) input signal into a
© NXP B.V. 2009. All rights reserved.
TFA9812
2
2
S audio
S master
2
S input
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