Specifications

Si2457/34/15/04
48 Rev. 1.3
9 MISO/RXD/RD Master In Slave Out/Receive Data/Read Enable.
Serial data output from modem in SPI mode. Data output to DTE RXD pin in
UART mode. Active low read enable pin in parallel mode.
10 MOSI/TXD/WR
Master Out Slave In/Transmit Data/Write Enable.
Serial data input to modem in SPI mode. Data input from DTE TXD pin in serial
mode. Active low write enable pin in parallel mode.
11 SCLK/CTS
/CS Serial Data Clock/Clear to Send/Chip Select.
Serial data clock input in SPI mode. Signals that the Si2457/34/15/04 is ready to
receive more digital data on the TXD pin in data mode. Active low chip select in
parallel mode.
12 RESET
Reset Input.
An active low input that is used to reset all control registers to a defined initialized
state.
13 C2A Isolation Capacitor 2A.
Connects to one side of the isolation capacitor, C2.
14 C1A Isolation Capacitor 1A.
Connects to one side of the isolation capacitor, C1.
15 AOUT/INT
Analog Output/Interrupt Output.
Analog output in serial mode. Active low interrupt output in parallel mode.
16 INT
/D0 Interrupt Output/Data Bit.
Active low interrupt output in serial mode. Bidirectional parallel bus data bit 0 in
parallel mode.
17 RI
/D1 Ring Indicator/Data Bit.
The RI
on (active low) indicates the presence of an ON segment of a ring signal
on the telephone line. Bidirectional parallel bus data bit 1 in parallel mode.
18 SDI/EESD/D2 Serial Data In/EEPROM Serial Data Input/Output/Data Bit.
Serial Data In (to codec) output in serial mode. Bidirectional Input/Output to SPI
EEPROM in serial mode when pin 4 is pulled low during power up. Bidirectional
parallel bus data bit 2 in parallel mode.
22 ESC/D3 Escape/Data Bit.
Hardware escape in serial mode. Bidirectional parallel bus data bit 3 in parallel
mode.
23 DCD
/D4 Carrier Detect/Data Bit.
Active low carrier detect in serial mode. Bidirectional parallel bus data bit 4 in par-
allel mode.
24 SDO/EECLK/D5 Serial Data Out/EEPROM Clock/Data Bit 5.
Serial Data Out (from codec) input in serial mode. Clock output for SPI EEPROM
in serial mode when pin 4 is pulled low during power up. Bidirectional parallel bus
data bit 5 in parallel mode.
Pin # Pin Name Description