ak4650 AKM Semiconductor, Inc., ak4650 Datasheet - Page 48

• Manufacturer Part Number: ak4650
• Description: 16bit 6 Codec With Mic/hp/spk-amp & Tsc
• Manufacturer: AKM Semiconductor, Inc.

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The AK4650 has an internal 2.5V voltage reference. This reference can be turned ON when PMVREF = “1”, and OFF
when PMVREF = “0”. This reference is used in the single-ended mode for the battery monitoring, or for auxiliary input.
A 0.1 F or larger capacitor should be connected for stable operation of the VREF circuit. Settling time depends on this
external capacitance, but 400 s or longer time is required if the external capacitance is 0.1 F.
If an external voltage reference is used, PMVREF bit should be set to “0”.
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The AK4650 can measure the battery voltage of 5V or less directly while the AK4650 operates at 2.7V to 3.6V. The input
voltage is internally divided down by four.
When the tracking time is adjusted at battery measurement, the method using ADEXE pin is available. ADEXE1-0 bits
select the tracking edge (Table 53).
MS0502-E-01
Voltage Reference (VREF)
Battery Measurement
VBAT
R0
AK4650
R2=2.5K
R1=7.5K
Figure 36. Battery Monitoring
Enable
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Internal
VREF
AIN+
AIN-
ADC
VREF+
PD1
VREF-
VREF
[AK4650]
2007/04