LMV1089RLEVAL National Semiconductor, LMV1089RLEVAL Datasheet - Page 14

• 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

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Performing a Three Tone Calibration
In a system with two microphones in an enclosure there will
always be a difference in the transfer function in both gain and
frequency response. The LMV1089 has the capability to per-
form an automatic calibration function to minimize these dif-
ferences. To perform this calibration, a test sequence of three
tones is required right after the PE and CAL inputs are brought
to a logic high level. At the end of this sequence the calibration
data is automatically stored in the internal EEPROM.
The three tones have to be applied as follows:
•
A first tone with a frequency of 1kHz
FIGURE 17. One Tone Calibration Timing
FIGURE 18. Calibration Timing
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•
•
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 18 and Table 5 are ignored by the calibration
system.
Between each tone pair there is a small time, indicated by a
cross, to change the frequency. During that time the input tone
is ignored by the calibration system.
The total calibration sequence requires less than 790ms.
A second tone with a frequency of 300Hz
A third tone with a frequency of 3kHz
300606r4
300606r3