SI3225-G-GQ Silicon Laboratories Inc, SI3225-G-GQ Datasheet - Page 53

• Manufacturer Part Number: SI3225-G-GQ
• Description: IC PROSLIC/CODEC DUAL 64TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3225-G-GQ

• Function: Subscriber Line Interface Concept (SLIC), CODEC
• Interface: GCI, PCM, SPI
• Number Of Circuits: 2
• Voltage - Supply: 3.3V, 5V
• Current - Supply: 65mA
• Power (watts): 941mW
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-TQFP, 64-VQFP
• Includes: Battery Switching, BORSCHT Functions, DTMF Generation and Decoding, FSK Tone Generation, Modem and Fax Tone Detection
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

To enable unbalanced ringing, set the RINGUNB bit of
the RINGCON register. As with internal balanced
ringing, the unbalanced ringing waveform is generated
by using one of the two on-chip tone generators
provided in the Si3220. The tone generator used to
generate ringing tones is a two-pole resonator with
programmable frequency and amplitude. Since ringing
frequencies are low compared to the audio band
signaling
generated at a 1 kHz rate.
The ringing generator is programmed via the RINGAMP,
RINGFREQ, and RINGPHAS registers. The RINGOF
register is used in to set the dc offset position around
which the RING lead will oscillate. Unbalanced ringing
is centered at –80 V instead of V
offset register (RINGOF, indirect Register 56) to position
the dc offset as desired. The dc offset is set at a dc point
equal to VCM – (–80 V + VOFF), where VOFF is the
value that is input into the RINGOF RAM location.
Positive VOFF values will cause the dc offset point to
move closer to ground (lower dc offset), and negative
VOFF values will have the opposite effect. The dc offset
can be set to any value; however, the ringing signal will
be clipped digitally if the dc offset is set to a value that is
less than half the ringing amplitude. In general, the
following equation must hold true to ensure the battery
voltage is sufficient to provide the desired ringing
amplitude:
|V
It is possible to create reverse polarity unbalanced
ringing waveforms (the TIP lead oscillates while the
RING lead stays constant) by setting the UNBPOLR bit
of the RINGCON register. In this mode, the polarity of
VOFF must also be reversed (in normal ringing polarity
VOFF is subtracted from –80 V, and in reverse polarity,
ringing VOFF is added to –80 V).
BATR
Figure 25. Internal Unbalanced Ringing
V
-80V
GND
BATR
V
| > |V
TIP
Si3220
frequencies,
V
RING,PK
OFF
V
DC Offset
RING
+ (–80 V + V
V
RING
the
DC Offset
ringing
OFF
BAT
) + V
V
V
OVRING
CM
RING
TIP
/ 2. Use the ring
OVRING
waveform
|
Rev. 1.3
is
3.14. Ringing Coefficients
The ringing coefficients are calculated in decimals for
sinusoidal and trapezoidal waveforms. The RINGPHAS
and RINGAMP hex values are decimal to hex
conversions in 16-bit 2’s complement representations
for their respective RAM locations.
To obtain sinusoidal RINGFREQ RAM values, the
RINGFREQ decimal number is converted to a 24-bit 2’s
complement value. The lower 12 bits are placed in
RINGFRLO bits 14:3. RINGFRLO bits 15 and 2:0 are
cleared to 0. The upper 12 bits are set in a similar
manner in RINGFRHI, bits 13:3. RINGFRHI bit 14 is the
sign bit, and RINGFRHI bits 2:0 are cleared to 0.
For
RINGFREQ = 0x7EFD9D are as follows:
RINGFRHI = 0x3F78
RINGFRLO = 0x6CE8
To obtain trapezoidal RINGFREQ RAM values, the
RINGFREQ decimal number is converted to an 8-bit, 2’s
complement value. This value is loaded into RINGFRHI.
RINGFRLO is not used.
3.14.1. Ringing DC Offset Voltage
A dc offset voltage can be added to the Si3220’s ac
ringing waveform by programming the RINGOF RAM
location to the appropriate setting. The value of
RINGOF is calculated as follows:
Figure 26. Trapezoidal Ringing Waveform
example,
Si3220/25 Si3200/02
V
TIP-RING
V
OFF
RINGOF
the
t
RISE
=
T = 1/freq
-------------- -
160.8
V
register
OFF
×
2
15
values
time
for
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