SI3233 datasheet(18/100 Pages) SILABS

18 / 100 page

Si3233

Preliminary Rev. 0.5

2. Functional Description

The Si3233 ProSLIC® is a feature-rich low-voltage

CMOS device that provides all the SLIC, DTMF, and

signal generation functions needed for a complete

analog telephone interface when connected to an

external codec. The ProSLIC performs all battery,

overvoltage, ringing, supervision, and test functions.

Unlike most monolithic SLICs, the Si3233 does not

require

externally

supplied

high-voltage

battery

supplies. It generates all necessary battery voltages

from a positive dc supply using its own dc-dc converter

controller. Two fully programmable tone generators can

produce DTMF tones, phase continuous FSK (caller ID)

signaling, and call progress tones. The Si3201 linefeed

interface IC performs all high voltage functions. The

Si3201 can also be replaced with low-cost discrete

circuits as shown in the typical application in Figure 6.

The Si3233 is designed to be used with Broadcom

devices

such

BCM1101,

BCM3351/52,

and

BCM6352. Special directions are required to interface

the Si3233 to other devices. Please contact Silicon

Laboratories for guidance.

The linefeed provides programmable on-hook voltage,

programmable off-hook loop current, reverse battery

operation, loop or ground start operation, and on-hook

transmission ringing voltage. Loop current and voltage

are continuously monitored using an integrated A/D

converter. Balanced 5 REN ringing with or without a

programmable dc offset is supported. Programmable

offset, frequency, waveshape, and cadence allow the

Si3233 to ring the widest variety of terminal devices and

to reduce external controller requirements.

2.1. Si3230 to Si3233 Differences

The hardware and software differences between the

Si3230 and the Si3233 are highlighted below for

customers migrating designs from the Si3230 to the

Si3233.

2.1.1. Hardware Changes

The Si3233 adds China and Japan impedances. See

"2.6. Two-Wire Impedance Matching" on page 34.

Pulse metering and DTMF detection are removed

from the Si3233.

External resistors R8 and R9 are changed from

470

Ω to 4.7 kΩ. See the typical application circuits

in Figure 3 on page 12 and Figure 6 on page 15.

The Si3233 adds PLL free-run mode. PLL free-run

mode is described in Section "2.8. PLL Free-run

Operation" on page 34.

2.1.2. Software Changes

The sample rate for the two-tone oscillators has

changed from 8 kHz to 16 kHz, therefore, the audio

tone coefficient equation has changed. See "2.4.2.

Oscillator Frequency and Amplitude" on page 27 for

a complete description.

The Si3233 provides an automatic calibration routine

for gain mismatch. Manual calibration is not

required. Refer to "AN35: Si321x User's Quick

Reference Guide".

The Indirect Registers have been re-mapped. When

porting code from the Si3230 to the Si3233, the

indirect register access function needs to be

modified. See"4. Indirect Registers" on page 85.

2.2. Linefeed Interface

The ProSLIC’s linefeed interface offers a rich set of

features and programmable flexibility to meet the

broadest application requirements. The dc linefeed

characteristics are software programmable; key current,

voltage, and power measurements are acquired in

realtime and provided in software registers.

2.2.1. DC Feed Characteristics

The ProSLIC has programmable constant voltage and

constant current zones as depicted in Figure 8. Open

circuit TIP-to-RING voltage (VOC) defines the constant

voltage zone and is programmable from 0 V to 94.5 V in

1.5 V steps. The loop current limit (ILIM) defines the

constant current zone and is programmable from 20 mA

to 41 mA in 3 mA steps. The ProSLIC has an inherent

dc output resistance (RO) of 160 Ω.

Figure 8. Simplified DC Current/Voltage

Linefeed Characteristic

The TIP-to-RING voltage (VOC) is offset from ground by

a programmable voltage (VCM) to provide voltage

headroom to the positive-most terminal (TIP in forward

polarity states and RING in reverse polarity states) for

carrying audio signals. Table 19 summarizes the

parameters to be initialized before entering an active

state.

(TIP-RING) (V )

Constant

Voltage

Zone

O=160 Ω

Constant Current

Zone

LIM

LOOP(m A )

SI3233 Datasheet(PDF) 18 Page - Silicon Laboratories

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