Si2401
Preliminary Rev. 0.9
67
Pin Descriptions: Si2401
Pin #
Pin Name
Description
1
CLKIN/XTALI
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.
2
XTALO
XTALO—Crystal Oscillator Pin.
Serves as the output of the crystal amplifier.
3
GPI05/RI
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.
4
V
D
Supply Voltage.
Provides the 3.3 V supply voltage to the Si2401.
5
RXD
Receive Data.
Serial communication data from the Si2401.
6
TXD
Transmit Data.
Serial communication data to the Si2401.
7
CTS
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.
8
RESET
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.
9
C2A
Isolation Capacitor 2A.
Connects to one side of the isolation capacitor C2.
10
C1A
Isolation Capacitor 1A.
Connects to one side of the isolation capacitor C1.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CLKIN/XTALI
XTALO
CTS
V
D
TXD
RXD
RESET
GPIO5/RI
GPIO1/EOFR
GPIO2/CD
GPIO3/ESC
V
A
GND
GPIO4/INT/AOUT
C1A
C2A