Silicon Laboratories Si3210 Design Manual

D G
E S I G N U ID E F O R T H E
1. Introduction
The ProSLIC® from Silicon Laboratories integrates a
complete analog telephone
low-voltage CMOS device and offers extensive software
programmability to meet many global telephony
requirements and customer specifications. In addition to
performing all BORSCHT functions, the Si321x also
dynamically generates and controls its own battery
voltage, eliminating the need for external battery
supplies. Two different battery generation architectures
are supported: a BJT/inductor design offering a low-cost
battery supply solution, and a MOSFET/transformer
design offering increased power efficiency and a wider
range of input voltages. This application note gives
Input
+
V
DC
–
Rev. 0.61 8/09
S i 3 2 1 0 / 1 5 / 1 6 D C - D C C
interface into one
Output
+
DC-DC
V
Converter BAT
–
Linefeed Circuitry
Figure 1. Linefeed Power Diagram
Copyright © 2009 by Silicon Laboratories
specific guidance in determining dc-dc converter power
requirements and selecting component values for each
of the dc-dc converter architectures.
1.1. Si321x DC-DC Converter Description
The dc-dc converter dynamically generates the large
negative voltages required to operate the linefeed
interface. The Si321x acts as the controller for a
buck-boost dc-dc converter that converts a positive dc
voltage into the desired negative battery voltage. In
addition to eliminating external power supplies, this
allows the Si321x to minimize power dissipation by
dynamically controlling the battery voltage to the
minimum required for any given mode of operation.
Twisted
Pair Line
R
LINE
2
TIP
+
V
TR
R
LINE
–
2
RING
Ringer
AN45
O N V E R T E R
Telephone
Hook SW.
RDC
AN45