TLC32047C Datasheet, PDF (9/61 Pages) Texas Instruments – Wide-Band Analog Interface Circuit

1 Introduction
The TLC32047 wide-band analog interface circuit (AIC) is a complete analog-to-digital and digital-to-analog
interface system for advanced digital signal processors (DSPs) similar to the TMS32020, TMS320C25, and
TMS320C30. The TLC32047 offers a powerful combination of options under DSP control: three operating
modes [dual-word (telephone interface), word, and byte] combined with two word formats (8 bits and 16 bits)
and synchronous or asynchronous operation. It provides a high level of flexibility in that conversion and
sampling rates, filter bandwidths, input circuitry, receive and transmit gains, and multiplexed analog inputs
are under processor control.
This AIC features a
• band-pass switched-capacitor antialiasing input filter
• 14-bit-resolution A/D converter
• 14-bit-resolution D/A converter
• low-pass switched-capacitor output-reconstruction filter
The antialiasing input filter comprises eighth-order and fourth-order CC-type (Chebyshev/elliptic
transitional) low-pass and high-pass filters, respectively. The input filter is implemented in switched-
capacitor technology and is preceded by a continuous time filter to eliminate any possibility of aliasing
caused by sampled data filtering. When low-pass filtering is desired, the high-pass filter can be switched
out of the signal path. A selectable auxiliary differential analog input is provided for applications where more
than one analog input is required.
The output-reconstruction filter is an eighth-order CC-type (Chebyshev/elliptic transitional low-pass filter)
followed by a second-order (sin x)/x correction filter and is implemented in switched-capacitor technology.
This filter is followed by a continuous-time filter to eliminate images of the sample data signal. The on-board
(sin x)/x correction filter can be switched out of the signal path using digital signal processor control.
The A/D and D/A architectures ensure no missing codes and monotonic operation. An internal voltage
reference is provided to ease the design task and to provide complete control over the performance of the
IC. The internal voltage reference is brought out to REF. Separate analog and digital voltage supplies and
ground are provided to minimize noise and ensure a wide dynamic range. The analog circuit path contains
only differential circuitry to keep noise to a minimum. The exception is the DAC sample-and-hold, which
utilizes pseudo-differential circuitry.
The TLC32047C is characterized for operation from 0°C to 70°C, and the TLC32047I is characterized for
operation from – 40°C to 85°C.
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