EM78568 データシートの表示（PDF） - ELAN Microelectronics
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EM78568 Datasheet PDF : 61 Pages
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EM78P568
8-bit OTP Micro-controller
(3) TX : transmitting audio
RXO
RXI
RXPWR
Rx AMP
VRF
MICO
MICI
VRX1
MUX
MIC AMP
MICO
MUX VTX1 ASW1 = 1
VRF
TXPWR = 1
AMUTE = 0
VRX3
CTCSS tone input
VTX3 MUX
(from DAC output buffer B2)
ASW3
RXPWR
BPFPWR = 1
ZC
DETO
Audio
BPF
MUX
ASW2 = 1
VRX2
VTX2
AURX
PORT65 MUX
AURX/P65
P65S
Sub-Audio
LPF
LPFPWR
MUX
0dB
VRX4
-10dB
VTX4
ASW4
VRF
Summing
AMP
MTX
PORT66 MUX
TXPWR = 1
P66S = 1
MTX/P66
(4) TX : transmitting CTCSS tone
Fig.20
RXO
RXI
RXPWR
Rx AMP
VRF
MICO
MICI
VRX1
MUX
MIC AMP
MICO
MUX VTX1 ASW1
VRF
TXPWR
AMUTE
VRX3
CTCSS tone input
VTX3 MUX
(from DAC output buffer B2)
ASW3 = 1
BPFPWR
Audio
BPF
Sub-Audio
LPF
LPFPWR = 1
RXPWR
ZC
DETO
MUX
ASW2
VRX2
VTX2
AURX
PORT65 MUX
AURX/P65
P65S
MUX
0dB
VRX4
-10dB
VTX4
VRF
ASW4 = 1
Summing
AMP
MTX
PORT66 MUX
TXPWR = 1
P66S = 1
MTX/P66
Fig.21
VII.10.2 Special application on Audio/CTCSS tone mixing output
Generally speaking, users can use built-in DAC tone gen.(described in VII.9) to generate CTCSS
tone accompanied with audio on MTX/P66 pin output without problem. For some customers, due to
modulation index criteria of their FM modulator cannot accept built-in CTCSS tone because this level is
too large for them to use.
In this case, there are two ways to solve this problem :
(1) One way is not to use built-in DAC tone gen. but need to program built-in DAC to generate CTCSS
tone by user software algorithm. User software algorithm can normalize the final CTCSS tone level
to their requirement without adding any external elements.
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* This specification are subject to be changed without notice.
46
01/31/2004 V4.7
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