si2401 Silicon Laboratories, si2401 Datasheet - Page 69

• Manufacturer Part Number: si2401
• Description: V.22bis Isomodem With Integrated Global Daa
• Manufacturer: Silicon Laboratories

8. Pin Descriptions: Si2401
Pin #
10
1
2
3
4
5
6
7
8
9
CLKIN/XTALI
Pin Name
GPI05/RI
RESET
XTALO
RXD
TXD
CTS
C2A
C1A
V
D
XTALI—Crystal Oscillator Pin.
These pins provide support for parallel resonant AT cut crystals. XTALI also acts as an
input in the event that an external clock source is used in place of a crystal. A
4.9152 MHz crystal is required or a 4.9152 or 27 MHz clock on XTALI.
XTALO—Crystal Oscillator Pin.
Serves as the output of the crystal amplifier.
General Purpose Input/RI.
This pin can be either a GPIO pin (digital in, digital out) or the RI pin. Default is digital
in. When programmed as RI, it indicates the presence of an ON segment of a ring
signal on the telephone line.
Supply Voltage.
Provides the 3.3 V supply voltage to the Si2401.
Receive Data.
Serial communication data from the Si2401.
Transmit Data.
Serial communication data to the Si2401.
Clear to Send.
Clear to send output used by the Si2401 to signal that the device is ready to receive
more digital data on the TXD pin.
Reset Input.
An active low input that is used to reset all control registers to a defined, initialized
state. Also used to bring the Si2401 out of sleep mode.
Isolation Capacitor 2A.
Connects to one side of the isolation capacitor C2.
Isolation Capacitor 1A.
Connects to one side of the isolation capacitor C1.
CLKIN/XTALI
GPIO5/RI
RESET
XTALO
RXD
CTS
TXD
V
D
1
2
3
4
5
6
7
8
Rev. 1.0
16
15
14
13
12
11
10
9
Description
GPIO1/EOFR
GPIO2/CD
GPIO3/ESC
GND
GPIO4/INT/AOUT
C1A
C2A
V
A
Si2401
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