Power
Management for
Mobiles (PM)
AT73C213
Audio Interface
for Portable
Handsets
2744A–PMGMT–27-Jan-05
Features
• Stereo Audio DAC
– 2.7V to 3.3V Analog Supply Operation
– 2.4V to 3.3V Digital Supply Operation
– 20-bit Stereo Audio DAC
– 93 dB SNR Playback Stereo Channels
– 32 Ohm/20 mW Stereo Headset Drivers with Master Volume and Mute Controls
– Stereo Line Level Input with Volume Control/mute and Playback through the
Headset Drivers
– Differential Monaural Auxiliary Input, with Volume Control/mute and Playback
through the Headset Drivers
– Accepts Mixed Signals from All Signal Paths (Line Inputs, External Mono and DAC
Output)
– 8, 11.024, 16, 22.05, 24, 32, 44.1 and 48 kHz Sampling Rates
– 256x or 384xFs Master Clock Frequency
– I2S Serial Audio Interface
Mono Audio Power Amplifier
– Supply Input from Main Li-Ion Battery
– 440mW on 8 Ohm Load
– Low Power Mode for Earphone
– Programmable Volume Control (-22 to +20 dB)
– Fully Differential Structure, Input and Output
– 8 mA Drain Current in Full Power Mode
– Power-down mode (Consumption Less than 2uA)
– Minimum External Components (Direct Connection of the Loudspeaker)
Applications: Mobile Phones, Digital Cameras, PDAs, SmartPhones, DECT Phones,
Music Players
1. Description
The AT73C213 is a fully integrated, low-cost, combined stereo audio DAC and audio
power amplifier circuit targeted for Li-Ion or Ni-Mh battery powered devices such as
mobile phones, smartphones, PDA, DECT phones, digital still cameras, music players
or any other type of handheld device where an audio interface is needed.
The stereo DAC section is a complete high performance, stereo audio digital-to-ana-
log converter delivering a 93 dB dynamic range. It comprises a multibit sigma-delta
modulator with dither, continuous time analog filters and analog output drive circuitry.
This architecture provides a high insensitivity to clock jitter. The digital interpolation fil-
ter increases the sample rate by a factor of 8 using 3 linear phase half-band filters
cascaded, followed by a first order SINC interpolator with a factor of 8. This filter elim-
inates the images of baseband audio, retaining only the image at 64x the input sample
rate, which is eliminated by the analog post filter. Optionally, a dither signal can be
added that reduces possible noise tones at the output. However, the use of a multibit
sigma-delta modulator already provides extremely low noise tone energy.
Master clock is from 256 or 384 times the input data rate, allowing choice of input data
rate up to 50 kHz, including standard audio rates of 48, 44.1, 32, 16 and 8 kHz.
The DAC section is followed by a volume and mute control and can be simultaneously
played back directly through a stereo 32 Ohm headset pair of drivers.