ucb1400 NXP Semiconductors, ucb1400 Datasheet - Page 21

• Manufacturer Part Number: ucb1400
• Description: Audio Codec With Touch Screen Controller And Power Management Monitor
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 09611
Product data
9.1.1 Line inputs
9.1.2 Microphone input
9.1.3 Decimation filter
The analog front-end of the UCB1400 consists of two stereo ADCs with a
programmable gain stage. The full scale input voltage of the line input path is
programmable in 1.5 dB steps independently for the left and right channels by setting
the GL[3:0] and GR[3:0] bits in the Record Gain Register (0x1C).
The UCB1400 audio codec input path accepts microphone signals via a DC blocking
capacitor. The ‘ground’ side of the microphone is either connected to the analog
ground (AV
current consumption of active microphones, since the MICGND pin is made Hi-Z
when the microphone input is not selected (SL = LINE_IN_L in Record Select register
(0x1A)).
The LNA gain can be set to 0 or 20 dB via the 20 dB bit in the MIC Volume register
(0x0E). Additional gain in 1.5 dB steps is possible via the GL[3:0] in the Record Gain
register (0x1C).
The decimation from 128 fs is performed in two stages. The first stage realizes
sin(x)/x characteristics with decimation factor of 16. The second stage consists of 3
half-band filters, each decimating by a factor of 2. The filter characteristics are shown
in
Table 6:
Item
Pass-band ripple
Stop band
Dynamic range
a.
Fig 15. Possible microphone connections.
Table
‘Passive’ microphone.
6.
Decimation filter characteristics
SS
) or to the MICGND pin of the UCB1400. The latter will decrease the
MICGND
AV
MICP
AV
Rev. 02 — 21 June 2002
DD
SS
UCB1400
SN00226
Condition
0 to 0.45 fs
> 0.55 fs
0 to 0.45 fs
Audio codec with touch screen controller
b.
‘Active’ microphone.
and power management monitor
© Koninklijke Philips Electronics N.V. 2002. All rights reserved.
Value (dB)
> 135
MICGND
0.015
60
MICP
AV
AV
DD
SS
UCB1400
UCB1400
SN00227
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