LMV1089RLEVAL National Semiconductor, LMV1089RLEVAL Datasheet - Page 13

• 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

Note: When the I
AUTOMATIC CALIBRATION VIA I
To initiate the automatic calibration via the I
following procedure is required:
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PERFORMING THE AUTOMATIC CALIBRATION
Automatic calibration can be performed as 'one tone' or as
'three tone' calibration. Three tone calibration is preferred be-
cause the three tone calibration not only compensates for
differences in the gain between the two microphones, but this
function also corrects for a difference in frequency response
between the two microphones and compensates for the
acoustical effects of the enclosure.
The one tone calibration only compensates for the gain dif-
ference between the two microphones at 1kHz and can lead
to less far field noise reduction when compared to three tone
calibration.
Performing a One Tone Calibration
The easiest way to perform an automatic calibration with the
LMV1089 uses one 1kHz tone. This tone can be a steady
From the initial condition where PE is 'low' level
Bring PE to a 'high' level (enable EEprom write)
Write '1' into I
calibration
Apply Audio stimulus (single tone 1kHz or three tone
sequence as described in Performing a One Tone
Calibration and Performing a Three Tone Calibration)
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 current than normal oper-
2
C is operated, make sure that register 'R' (address 0x12)
2
C register 'R' (address 0x12) bit 0 to start
2
C COMMAND
FIGURE 15. Automatic Calibration via CAL pin
2
interface, the
FIGURE 16.
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A tone may be applied prior to the rising of PE or setting the
I
before rising of PE or setting the I
by the calibration system.
state tone or a 1kHz tone that is switched on and off using the
timing from Figure 17.
To perform a one tone calibration, a 1kHz test tone is required
right after the PE and CAL inputs are brought to a logic high
level and that tone should be stable during the time as indi-
cated in Figure 17. At the end of this sequence the calibration
data is automatically stored in the internal EEPROM.
A tone may be applied prior to the rising of CAL start signal
and PE. Signals applied to the microphone outside the limits
shown in Figure 17 andTable 5 are ignored by the calibration
system.
2
C calibration bit . Signals applied to the microphone inputs
Wait at least 790ms
Remove Audio stimulus
Write '0' into I
Bring PE to a 'low' level (disable EEprom write)
ation. The state of the calibration remains active until this bit is reset,
'0”. With the bit set the 'low' to' high' transfer of the CAL pin will be
ignored.
2
C to finish calibration
300606r1
300606r2
2
C calibration bit are ignored
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