Si3220/25
Symbol
Input/
Output
Description
Pin Number(s)
Si3220 Si3225
46
46
SDITHRU
O
Serial Data Daisy Chain.
Enables multiple devices to use a single CS for serial port con-
trol. Connect SDITHRU pin from master device to SDI pin of
slave device. An internal pullup resistor holds this pin high dur-
ing idle periods.
47
47
53
CS
I
I
Chip Select.
Active low. When inactive, SCLK and SDI are ignored, and
SDO is high impedance. When active, serial port is operational.
BLKRNG
Ring Generator Sensing Input.
Senses ring-trip condition when using centralized ring genera-
tor. Connect to high side of ring sense resistor. Shared by
channels a and b.
epad
epad
GND
Exposed Die Paddle Ground.
Connect to a low-impedance ground plane via top side PCB
pad directly under the part. See Package Outlines: 64-Pin
TQFP for PCB pad dimensions.
Rev. 1.2
103
SILICON [ SILICON ]
