AK2347B Datasheet, PDF (5/34 Pages) Asahi Kasei Microsystems – Two-way Radio Audio & Sub-Audio Processor

ASAHI KASEI
[AK2347B]
Block
DTA1
Sub-Audio
Programmable LPF
VR5
AGND
OSC
Control
Register
Function
Operational amplifier for gain adjustment of the Sub-Audio LPF input signal and for the
filter for preventing aliasing noise in the SCF circuit in the subsequent stage. Use
external resistors and capacitors to set the gain to 0dB or less and the cut-off frequency
to around 10kHz.
Low-pass filter to eliminate components of the DAT1 signal in the transmit operation and
of RXA1 signal in the receive. This circuit is controlled by the SASW register for transmit
or receive and by the SA5 to SA0 for cut-off frequency.
This circuit controls the volume for adjusting the output level from the Sub-Audio LPF
signal.
Setting registers: VR54 to VR50, adjustment range: -6.0dB to +6.0dB in 0.5dB steps
This circuit generates the reference voltage (1/2VDD) for internal analog signals.
This circuit generates a 3.6864MHz or 3.579545MHz reference clock signal from an
external resistor and crystal oscillator. This circuit is controlled by the MCKSL register.
Control registers set the switch status and volume for level adjustment inside the IC
according to the serial input data consisting of 1-bit instruction and 4-bit address and
8-bit data. At power-up, the registers are set to the power-down values by the power-on
reset circuit. This circuit has a software reset named RSTN register.
(See the description of the registers)
6. Pin Functions
Pin
number
Pin name
1 AGNDIN
2 AGND
3 TXINO
4 TXIN
5 EXTIN
6 EXTINO
7 LIMLV
8 MOD
9 VSS
10 SDATA
Pin
type
AI
AO
AO
AI
AI
AO
AI
AO
PWR
DB
Power-
down
status
*3)
*3)
Function
Analog ground input pin
This pin is connected to a capacitor to stabilize the analog ground
level.
Analog ground output pin
This pin is connected to a capacitor to stabilize the analog ground
level.
Z Output pin of TXA1 *1)
Transmit audio signal input pin
Z This pin is the inverting input pin of TXA1. This pin, with resistors
and capacitors externally connected, forms a microphone amplifier.
External input pin
This pin is the inverting input pin of TXA2. This pin, with resistors
Z and capacitors externally connected, forms a amplifier.
An external signal such as a tone signal other than the audio signal
can be input.
*3) Output pin of TXA2 *1)
Limit level adjustment pin
*4)
The limit level can be adjusted by applying a DC voltage to this pin.
When this pin is left open, the limit level predetermined within the
device is set.
Z Modulated transmit signal output pin *2)
-
Negative power supply pin
Normally, apply 0V.
Z Serial data input and output control pin
MS1419-E-00
-5-
2012/05