sta538 STMicroelectronics, sta538 Datasheet - Page 23

• Manufacturer Part Number: sta538
• Description: 2 X 1.3 W Class-d Amplifier With Analog Or Digital Input 2.0 Multichannel Digital Audio Processor With Ffx
• Manufacturer: STMicroelectronics

STA538
6
6.1
6.1.1
Functional description
ADC
This section describes the analog-to-digital converter (ADC).
The STA538 analog input is provided through a low power, low voltage, stereo audio analog-
to-digital converter front-end designed for audio applications. It includes a programmable
gain amplifier, anti-aliasing filter, low-noise microphone biasing circuit, a third-order
MASH2-1 delta-sigma modulator, digital decimating filter, and a first-order DC-removal filter.
This device is fabricated using a 0.18
analog circuits are combined with high-density logic circuits.
The ADC works in a microphone input (mic-in) mode and in a line-input mode.
If the line input mode is selected, the ADC is configured in stereo and all conversion
channels are active.
If the microphone input mode is selected, the ADC is configured in mono. The mono
channel is routed through the left conversion path, and the right conversion path is kept in
power-down mode to minimize power consumption. A programmable gain amplifier (PGA) is
available in mic-in mode, giving the possibility to amplify the signal from 0 to +42 dB in steps
of 6 dB.
Digital filter characteristics
The digital filter characteristics are shown in
Table 15.
Passband
Passband ripple:
Stop band attenuation:
Group delay:
Fs mode
Fs_by_2 mode
Fs_by_4 mode
Fs mode
Fs_by_2 mode
Fs_by_4 mode
Fs mode
Fs_by_2 mode
Fs_by_4 mode
Parameter
Digital filter characteristics
0.08 at 11.025 kHz
µ
0.08 at 22.05 kHz
45 at 11.025 kHz
0.08 at 44.1 kHz
45 at 22.05 kHz
m CMOS process, where high-speed precision
45 at 44.1 kHz
0.4 at 32 kHz
0.7 at 16 kHz
1.4 at 8 kHz
0.4535 * Fs
Typical
Table
15.
Unit
kHz
ms
ms
ms
dB
dB
dB
dB
dB
dB
23/59
ADC