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AK2345 Schematic ( PDF Datasheet ) - Asahi Kasei Microsystems

Teilenummer AK2345
Beschreibung FRS CTCSS Encoder/Decoder
Hersteller Asahi Kasei Microsystems
Logo Asahi Kasei Microsystems Logo 




Gesamt 27 Seiten
AK2345 Datasheet, Funktion
ASAHI KASEI
[AK2345]
AK2345
FRS CTCSS Encoder/Decoder
Features
1. CTCSS (Continuous Tone Controlled Squelch System) Encoder/Decoder.
2. Programmable for up to 50 CTCSS frequencies.
3. Integrated CTCSS signal elimination filter.
4. Built-in Adder TX CTCSS/CDCSS and voice signal.
5. Built-in high speed CTCSS Decoder.
6. Conform to CDCSS. (Continuous Digital Controlled Squelch System)
7. Integrated voice signal circuits such as a limiter, splatter filter, etc.
8. Built-in (3.6864 MHz or 4.194304 MHz) oscillator circuit with crystal oscillator.
9. Control register controlled via serial interface.
10. CMOS Process low voltage operation. (1.8V…5.5V)
11. Compact plastic package is used. (24 pin VSOP)
(Page 25)
Description
The AK2345 is an IC which supports CTCSS (Continuous Tone Controlled Squelch System),
compatible with the TIA/EIA-603 standard.
A single CTCSS may be selected from among 50 different frequencies within a range of from
67 to 254.1 Hz. By sending that CTCSS simultaneously with the voice signal during
transmission, and by setting the audio circuit so that it operates only when a CTCSS of that
frequency is detected, it is possible to have multiple communications on the same radio
frequency.
TX has a built-in Adder CTCSS and voice signal, and RX has a built-in high-speed CTCSS
Decoder respectively.
Voice signal filters, a limiter, op-amp, and other circuits are integrated, making it possible to
configure a radio base band unit, especially FRS from a single chip.
Pin assignment
TXIN1
TXIN2
TXINO
MOD
MODIN
SPOUT
RXOUT
VDD
XIN
XOUT
STB
SDATA/DCS
1
2
3
4
5
6
7
8
9
10
11
12
24 RXTONE
23 RXIN
22 RXINO
21 AGNDIN
20 AGND
19 LIMLV
18 LIMBS
17 DREF
16 TXTONE
15 VSS
14 DETOUT
13 SCLK
C0041-E-03
-1-
2006/09






AK2345 Datasheet, Funktion
ASAHI KASEI
[AK2345]
Pin No. Pin Name
14 DETOUT
15 VSS
16 TXTONE
17 DREF
18 LIMBS
19 LIMLV
20 AGND
21 AGNDIN
22 RXINO
23 RXIN
24 RXTONE
I/O Function
CTCSS detects signal output pin. (Open drain output)
O
When in the receive mode, if a CTCSS at the frequency
set by serial data is detected; this signal goes “Low”.
In the transmit mode, it is high impedance at all times.
-
Negative power supply pin.
A voltage of 0V is applied.
Transmit CTCSS/CDCSS monitor pin.
When in the transmit mode, CTCSS of the frequency set
by serial data is output from this pin. CDCSS codes
from CPU input into SDATA/DCS pin, which is limited by
O TSQLPF1, is also output from this pin.
When in the receive mode, the AGND level is output.
When in the standby state, the impedance at this
terminal becomes high.
It can drive a 10kohm (AC resistance) or higher load.
CTCSS detect level adjust pin. The CTCSS decoder's
threshold level is determined by applying a DC voltage
I greater than the AGND level to this pin.
It is computed by Vth=0.575VDD formula.
( Refer to Page 21 and 24)
Limiter level fine adjustment pin.
I
By applying a DC voltage to this pin, fine adjustment of
the lower limit limiter level can be done and the limiter's
symmetry can be adjusted.
Limiter level adjustment pin.
I
The limit level can be adjusted by applying the DC
voltage to this pin. If no connections are made,
the pre-determined limiter level is set.
Analog ground pin. A 1/2VDD voltage, which
O becomes the reference for the analog circuit, is output.
Connect a capacitor to stabilize the analog ground.
I
Analog ground input pin. Connect a capacitor to
stabilize the analog ground.
O
AMP2 output pin. This pin can drive a 30kΩ (AC
resistance) or greater load.
Receive demodulation signal input pin. This is the
I inverted input of AMP2. A pre filter is configured by
connecting resistors and capacitors externally.
Receiving CTCSS/CDCSS monitor pin.
O
In the Receive mode, the designated CTCSS/CDCSS is
selected from the receiving signal. This pin can drive a
10kΩ (AC resistance) or greater load.
C0041-E-03
-6-
2006/09

6 Page









AK2345 pdf, datenblatt
ASAHI KASEI
[AK2345]
Level Diagram
1) TX System
TXAF
AMP1
30dB
at 1kHz
dBx
0
TXTONE
-10dBx
BPF
0dB
VR1
Adder
Limiter
Limiter Level
-8dBx
Splatter
Filter
0dB
AMP3
MOD
Voice:0dB
CTCSS:-10/-20dB
-5
Standard
voice level
-10
-10
-15
-20 -20
CTCSS
-25
-30 -30
-35
-40
2) RX System
DEM
AMP2
BPF
RXOUT
20dB
0dB
TXQBPF1
AMP4
TSQLIM
DETECT
TSQBPF2
13dB
22.5dB
~0dB
Limit Level
-7dBx
dBx (22.5dB)
0
Standard
-10 voice level
-2.5(22.5dB)
-7
-4.9
-10
Standard -12.4 (0dB)
-20 CTCSS level
-25.4
-25(0dB)
-30
-40
-45.4
-50
-38
Min. detection
CTCSS level
-60 -58
Note) when AMP2 is used as De-emphasis, the level diagram of CTCSS is changed.
C0041-E-03
- 12 -
2006/09

12 Page





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