uda1380 NXP Semiconductors, uda1380 Datasheet - Page 13

• Manufacturer Part Number: uda1380
• Description: Uda1380 Stereo Audio Coder-decoder For Md, Cd And Mp3
• Manufacturer: NXP Semiconductors

Philips Semiconductors
8.2
The analog front-end of the UDA1380 consists of one
stereo ADC with a selector in front of it (see Fig.6). Using
this selector one can either select the microphone input
with the microphone amplifier (LNA) with a fixed 29 dB
gain and VGA (no PGA, since a real microphone amplifier
is much better with respect to noise), or the line input which
has a PGA for having 0 or 6 dB gain (for supporting 1 and
2 V (RMS) input). The PGA also provides gain control from
0 to 24 dB in steps of 3 dB.
Remark:
8.2.2
The LNA is equipped with a VGA. The function of the VGA
is to have additional variable analog gain from 0 to 30 dB
in steps of 2 dB. This provides more flexibility in the choice
of the microphone.
2004 Apr 22
handbook, full pagewidth
The input impedance of the PGA (line input) is 12 k , for
the LNA this is 5 k
Stereo audio coder-decoder
for MD, CD and MP3
Pin numbers for UDA1380HN in parentheses.
ADC analog front-end
LNA
WITH
VGA
VINR
VINM
VINL
(29)
(27)
(31)
1
31
3
PGA
PGA
LNA
Fig.6 Analog front-end.
SDC
SDC
SDC
13
SEL_LNA
8.2.1
The following Power-down modes and functional modes
are supported:
More information on the analog frond-end is given in
Section 8.11.1.
8.2.3
For the line input it is preferable to have 0 dB and 6 dB
gain settings in order to be able to apply both
1 and 2 V (RMS) input signals, using a series resistance.
For this purpose a PGA is used which has 0 to 24 dB gain,
in steps of 3 dB.
Power-down mode in which the power consumption is
very low (only leakage currents)
In this mode there is no reference voltage at the line
input
Line input mode, in which the PGA can be used
Microphone mode, in which the rest of the non-used
PGAs and ADCs are powered-down
Mixed PGA and LNA mode: one line input and one
microphone input.
ADC
ADC
A
A
PPLICATIONS AND
PPLICATIONS WITH
SEL_MIC
MGU530
bitstream
right
bitstream
left
P
2 V (
OWER
RMS
-
DOWN MODES
Product specification
)
INPUT
UDA1380