xe3006 Semtech Corporation, xe3006 Datasheet - Page 17

• Manufacturer Part Number: xe3006
• Description: Sandman? Codec | Semtech
• Manufacturer: Semtech Corporation

4
The Sandman™ function analyzes the audio signals in the ADC and DAC. Its output signals indicate whether an audio
signal is present in the ADC or DAC or if the processed signal is just noise. The threshold or reference value between
noise and audio signal as well as the minimum duration of an audio signal is user-programmable through the SPI
interface. If the XE3006 CODEC is used in a system that includes a microcontroller, a DSP or an RF link, the outputs of
the Sandman™ Interface can be used to bring these devices into standby or sleep mode whenever no audio signal is
being processed. In this way, the Sandman™ function contributes to significant additional power savings on the system
level outside the XE3006 chip.
The Sandman™ Interface consists of 2 digital outputs:
The Sandman™ Interface is implemented for the ADC and for the DAC in an identical way. It works with a set of 4 user-
defined parameters: off time, on-time, ADC-reference and DAC-reference. The on time and the off time are the same for
ADC and DAC. However, the reference values for the ADC and the DAC are adjusted separately, as indicated in the
table below.
The Sandman™ Interface (for the ADC as well as for the DAC) is configured with three parameters:
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• The SMAD detects whether the ADC processes an audio signal. The calculation is made with the digital data leaving
• The SMDA detects whether an audio signal is processed by the DAC. The calculation is made with the digital data
• Reference (7:0): Absolute value under which the signal is considered noise and above which the signal is
• Off-time (15:0): Time until power down. The number of sequential samples that have to be lower than the
the ADC.
entering through the Audio Interface.
considered to be an audio signal. The Sandman™ function is disabled (SMAD or SMDA at logic 1) if this parameter
is zero. The ADC and the DAC have separate Reference values.
Reference for the power down signal to become active. The Sandman™ function is disabled (SMAD or SMDA at
logic 1) if this parameter is zero. The ADC and DAC have one common Off-time value.
SANDMAN™ FUNCTION (XE3006)
mosi
sck
ss
ADC_reference(7:0)
DAC_reference(7:0)
Input parameters
Off-time2(15:8)
Off-time1(7:0)
On-time(7:0)
1
request (write to address A(4:0))
0
0
Figure 18: SPI signal timing in write mode
A4
A3
Register
M
O
N
P
L
A2
A1
17
A0
Sandman ADC
msb
write data D(7:0) to address A(4:0)
X
X
X
X
-
XE3005/XE3006
Sandman DAC
X
X
X
X
-
lsb
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