LMV1089RLEVAL National Semiconductor, LMV1089RLEVAL Datasheet - Page 23

• Manufacturer Part Number: LMV1089RLEVAL
• Description: BOARD EVALUATION LMV1089
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LMV1089RLEVAL

• Main Purpose: Audio, Microphone Amp
• Embedded: No
• Utilized Ic / Part: LMV1089
• Primary Attributes: Dual Input, Single Output
• Secondary Attributes: Graphical User Interface, I²C Interface
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Calibration
Automatic calibration should only be required once, when the
product containing the LMV1089 has completed manufac-
ture, and prior to application packaging. The product contain-
ing the LMV1089 will be calibrated to the microphones, the
microphone spacings, and the acoustical properties of the fi-
nal design.
The compensation or calibration technology is achieved via
memory stored coefficients when the FFNS circuitry activates
the calibration sequence. The purpose of the calibration se-
quence is to choose the optimized coefficients for the FFNS
circuitry for the given microphones, spacing, and acoustical
design of the product containing the LMV1089.
A basic calibration can be performed with a single 1kHz tone,
however to take full advantage of this calibration feature a
three tone calibration (See
CALIBRATION) is preferred .
The automatic calibration process can be initiated from either
a digital interface CALIBRATE pin (CAL) or via the I
face.
The logic level at the PROGRAM ENABLE (PE) pin deter-
mines if the result of the calibration is volatile or permanent.
Note: When the I
0x12) bit 0 is '0' before operating the CAL pin (default value for
this bit). When this bit is set '1' the calibration engine of the
LMV1089 is started and will remain active with a higher supply
2
C is operated, make sure that register 'R' (address
PERFORMING A THREE TONE
FIGURE 9. Automatic Calibration via CAL pin
2
C inter-
23
To make the result of the calibration permanent (stored in the
EEPROM) the PROGRAM ENABLE (PE) pin must be high
during the automatic calibration process.
AUTOMATIC CALIBRATION VIA CAL PIN
To initiate the automatic calibration via the CAL pin, the fol-
lowing procedure is required. See timing diagram Figure 11:
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A tone may be applied prior to the rising of CAL and PE. Sig-
nals applied to the microphone inputs before rising of CAL
and PE are ignored by the calibration system.
From the initial condition where both PE and CAL are at
'low' level
bring PE to a 'high' level (enable EEprom write)
bring CAL to a 'high' level to start Calibration
Apply Audio stimulus (single tone 1kHz or three tone
sequence as described in
TONE
Hold CAL 'high' for at least 790ms
Remove Audio stimulus
bring CAL to a 'low' level to stop Calibration
bring PE to a 'low' level (disable EEprom write)
current than normal operation. The state of the calibration re-
mains active until this bit is reset, '0”. With the bit set the 'low'
to' high' transfer of the CAL pin will be ignored.
CALIBRATION) (see Figure 12).
300472r1
PERFORMING A THREE
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