RC56D, RC336D, and RC144D Modem Device Sets Designer’s Guide
1154
Conexant
3-17
Table 3-7. RCDSVD SCP Pin Signal Definitions
Label
I/O Type
Signal/Definition
SYSTEM SIGNALS
XTLI, XTLO
R, R
Crystal In and Crystal Out. Connect to an external 56.448 MHz fundamental or third overtone crystal
circuit, oscillator circuit, or the MDP XCLK pin..
~RESET
ID
Reset. After application of +5V power, ~RESET must be held low for at least 15 ms after the +5V power
reaches operating range. The SCP is ready to use 25 ms after the low-to-high transition of ~RESET. The
reset sequence initializes the SCP interface memory to default values. Connect to the modem ~RES pin.
~IARESET
IA
IA Reset. Connect to the SCP ~SLEEPO pin and to GND through 10 k
Ω
.
~SLEEPO
OA
Sleep Out. Connect to the SCP ~IARESET pin.
~EN85
IA
Enable 85 Bus. Connect to GND through 20 k
Ω
.
VDD
PWR
+ 5V Digital Supply Voltage for Digital Circuits. Connect to VCC.
ADVDD
PWR
+ 5V Digital Supply Voltage for Analog Circuit. Connect to VCC.
AVDD
PWR
+ 5V Analog Supply Voltage for Analog Circuit. Connect to VCC through decoupling circuit.
VSS
GND
Digital Ground. Connect to digital ground.
ADVSS
GND
Digital Ground for Analog Circuit. Connect to digital ground.
AVSS
GND
Analog Ground. Connect to analog ground.
MODEM INTERFACE
D0–D7
IA/OB
Data Lines. Connect to the modem external bus D0-D7 lines, respectively.
RS0–RS4
IA
Register Select Lines. Connect to the modem external bus A0–A4 lines, respectively.
~CS
IA
Chip Select. Connect to the modem ~SVDCS line.
~READ
IA
Read Enable. Connect to the modem external bus ~READ line.
~WRITE
IA
Write Enable. Connect to the modem external bus ~WRITE line.
IRQ
IA
Interrupt Request. Connect to the modem IRQ line.
TELEPHONE LINE/AUDIO INTERFACE
MICIN
I(DA)
Microphone In. MICIN is a single-ended input from the audio interface circuit for routing from
microphone input.
SPKP
O(DF)
Speaker Out Positive. The SPKP is a single-ended output to the audio interface circuit for routing to
speaker. The output can drive a 300
Ω
load.
LINEIN
I(DA)
Line In Analog Input. LINEIN is a single-ended input from the audio interface circuit for routing from the
telephone line through the hybrid circuit.
LINEOUT
O(DF)
Line Out Analog Output. LINEOUT is a single-ended output to the audio interface circuit for routing to
the telephone line through the hybrid circuit. The output can drive a 300
Ω
load.
REFERENCE SIGNALS
VREF
REF
High Voltage Reference. Connect to VC through 10 µF (polarized, + terminal to VREF) and 0.1 µF
(ceramic) in parallel.
VC
REF
Low Voltage Reference. Connect to analog ground through 10 µF (polarized, + terminal to VC) and 0.1
µF (ceramic) in parallel.
RBIAS
REF
Reference Bias. Connect to analog ground through 120 k
Ω
.
Содержание RC144D
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