SI3021 datasheet(47/54 Pages) ETC

47 / 54 page

Si3035

Rev. 1.2

Mode Select 1 Input.

The second of two mode select pins that is used to select the operation of the

serial port/DSP interface.

C1A

Isolation Capacitor 1A.

Connects to one side of the isolation capacitor C1. Used to communicated

with the line-side device.

GND

Ground.

Connects to the system digital ground.

Analog Supply Voltage.

Provides the analog supply voltage for the Si3021, nominally 5 V. This supply

is typically generated internally with an on-chip charge pump set through a

control register.

Mode Select 0 Input.

The first of two mode select pins that is used to select the operation of the

serial port/DSP interface.

RGDT/FSD

Ring Detect/Delayed Frame Sync Output.

Output signal that indicates the status of a ring signal. Produces an active

low rectified version of the ring signal. When daisy chain is enabled, this sig-

nal becomes a delayed frame sync to drive a slave device.

OFHK

Off-Hook Input.

An active low input control signal that provides a termination across TIP and

RING for line seizing and pulse dialing.

Table 21. Si3021 Pin Descriptions (Continued)

SOIC

Pin #

TSSOP

Pin #

Pin Name

Description

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