AK4650 Datasheet, PDF (48/86 Pages) Asahi Kasei Microsystems – 16Bit ΔΣ CODEC with MIC/HP/SPK-AMP & TSC

[AK4650]
■ Voltage Reference (VREF)
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 0.1μF or larger capacitor should be connected for stable operation of the VREF circuit. Settling time depends on this
external capacitance, but 400μs or longer time is required if the external capacitance is 0.1μF.
If an external voltage reference is used, PMVREF bit should be set to “0”.
■ Battery Measurement
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).
AK4650
VBAT
R0
R1=7.5K
R2=2.5K
Internal
VREF
VREF
PD1
AIN+
VREF+
ADC
AIN-
VREF-
Enable
Figure 36. Battery Monitoring
MS0502-E-01
- 48 -
2007/04