AK2301A Datasheet, PDF (12/20 Pages) Asahi Kasei Microsystems – 3.3V Single channel PCM CODEC LSI

ASAHI KASEI
AK2301A
CIRCUIT DESCRIPTION
BLOCK
AMPT
AMPR
AAF
CODEC
A/D
CODEC
D/A
SMF
BGREF
PCM I/F
AMP1、AMP2
FUNCTION
Op-amp for input gain adjustment. This op-amp is used as an inverting or
differential amplifier. Adjusting the gain with external resistors. The resistor
should be larger than 10kΩ for the feedback resistor.
VFTN: Negative op-amp input.
VFTP: Positive op-amp input.
GST: Op-amp output.
Op-amp for output gain adjustment. This op-amp is used as an inverting
amplifier. Adjusting the gain with external resistors. The combined resistor larger
than 8kΩ is recommended for the feedback and the output load
VFR: Negative op-amp input.
GSR: Op-amp output.
VR and GSR can be used as the differential output.
Integrated anti-aliasing filter which prevents signals around the sampling rate
from folding back into the voice band. AAF is a 2^nd order RC active low-pass filter.
Converting the analog signal to 14bit PCM data.
The band limiting filter is also integrated.
Converting the 14bit PCM data from the DR to the analog signal.
Output of the D/A converter is fed into the SMF to suppress the high frequency
element.
Extracts the inband signal from D/A output. It also corrects the sinx/x effect of the
D/A output.
Provide the stable analog ground voltage using an on-chip band-gap reference
circuit which is temperature compensated. The output voltage is 1.5V for 3.3V
An external capacitor of 1.0uF or larger should be connected between VREF and
VSS to stabilize analog ground (VREF). Please do not connect external load to
this pin. TAGND pin is used as the analog ground level output for the AMPT. An
external capacitor of 1.0uF or larger should be connected between TAGND and
VSS to stabilize analog ground.
For the PCM data rate, both 256kHz or 512kHz are available.
The 14bit PCM data is input/output by the 2’s compliment 16bit serial data
format. Two kinds of serial data format (Long Frame/Short Frame) are available.
Each data format is automatically detected by AK2301A.
PCM data is input to DR pin and output from DX pin.
Universal op-amp for the filter of the external voice path.
The maximum load is 8kΩ (including the feedback resistor and AC load).
These op-amps are assumed as using for the inverting LPF with 20kHz cut off
frequency.
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