PCM3793A
PCM3794A
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SLAS529A–JANUARY 2007–REVISED FEBRUARY 2007
Digital Monaural Mixing
The audio data can be converted from stereo digital data to mixed monaural digital data. The conversion occurs
in the internal audio interface section and is controlled by register 96 (MXEN).
Zero-Cross Detection
Zero-cross detection minimizes audible zipper noise while changing analog volume and digital attenuation. This
function applies to the digital input or digital output as defined by register 86 (ZCRS).
Short Protection
The short-circuit protection on each headphone output prevents damage to the device while an output is shorted
to VPA, an output is shorted to PGND, or any two outputs are shorted together. When the short circuit is detected
on the outputs, the PCM3793A/94A powers down the shorted amplifier immediately. The short-protection status
can be monitored by reading register 77 (STHC, STHL, SCHR) through the I2C interface. Short-circuit protection
operates in any enabled headphone amplifier.
Thermal Protection
The thermal protection on the speaker amplifier prevents damage to the device when the internal die
temperature exceeds approximately 150°C. Once the die temperature exceeds the thermal set point, all analog
outputs are powered down. This status can be reset by setting register 76 (RLSR, RLSL) and can be watched
by reading register 77 (STSR, STSL) through the two-wire (I2C) interface. Thermal protection operates in any
enabled speaker amplifier.
Pop-Noise Reduction Circuit
The pop-noise reduction circuit prevents audible noise when turning the power supply on/off and powering the
device up/down in portable applications. It is recommended to establish the register settings in the sequence
that is shown in Table 3 and Table 4. No particular external parts are required.
Power Up/Down for Each Module
Using register 72 (PMXL, PMXR), register 73 (PBIS, PDAR, PDAL, PHPC, PHPR, PHPL, PSPR, PSPL), register
82 (PAIR, PAIL, PADS, PMCB, PADR, PADL), and register 90 (PCOM), unused modules can be powered down
to minimize power consumption (7 mW during playback only and 13 mW when recording only).
Digital Audio Interface
The PCM3793A/94A can receive I2S, right-justified, left-justified, and DSP formats in both master and slave
modes. These options can be selected in register 70 (PFM[1:0]), register 81 (RFM[1:0]) and register 84 (MSTR).
Digital Interface
All digital I/O pins can interface at various power supply voltages. VIO pin can be connected to a 1.71-V to 3.6-V
power supply.
Power Supply
The VCC pin and the VPA pin can be connected to 2.4 V to 3.6 V. The same voltage must be applied to both pins.
The VDD pin and the VIO pin can be connected to 1.71 V to 3.6 V. A different voltage can be applied to each of
these pins (for example, VDD = 1.8 V, VIO = 3.3 V).
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