SI3200-GS Silicon Laboratories Inc, SI3200-GS Datasheet - Page 5

• Manufacturer Part Number: SI3200-GS
• Description: IC LINEFEED INTRFC 100V 16SOIC
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3200-GS

• Function: Subscriber Line Interface Concept (SLIC), CODEC
• Interface: GCI, PCM, SPI
• Number Of Circuits: 2
• Voltage - Supply: 3.3V, 5V
• Current - Supply: 110µA
• Power (watts): 941mW
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• 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
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

In the case of the linear regulator, the system designer
must consider the manufacturer’s rated maximum
power dissipation of the Zener diode and transistor and
ensure that these ratings are not exceeded under all
expected operating conditions. The manufacturer’s
recommended PCB footprint for the Zener diode and
transistor must be followed to ensure proper heat
dissipation.
As with any line card system design, the designer must
take into consideration proper ventilation and airflow to
carry heat away from power-dissipating components in
the system and to ensure that the maximum allowable
ambient temperature within the system enclosure is not
exceeded under all expected operating conditions.
Battery Switching Threshold
Settings
The Si322x device provides two threshold registers that
allow software to select the thresholds at which the
system switches battery supply. Two thresholds are
used to provide hysteresis. The value of the BATHTH
RAM location determines the RING dc voltage at which
the system switches from VBLO to VBHI upon going on-
hook. The value of BATLTH determines the RING dc
voltage at which the system switches from VBHI to
VBLO upon going off-hook.
The value of BATLPF determines corner frequency of
the digital low-pass filter used to filter the RING dc
voltage for the purposes of comparing against the set
thresholds.
For a given loop condition, the SLIC must be able to
supply enough voltage to the loop (V
state, and maintain the required overhead voltage
(V
Equation 11 (see “DC Feed Characteristics” in the
Si3220/Si3225 Data Sheet for a more detailed
explanation of V
V
the loop, as shown in Equation 12.
The optimal battery-switching threshold is selected
based upon the ability of VBLO to satisfy Equation 11.
So long as VBLO is able to satisfy the requirement in
Equation 11, the VBLO battery source must be selected.
tr
oh
is the product of ILIM and the total dc resistance of
= V
Equation 11.Battery Voltage Requirement
cm
+ V
Equation 12.TIP-RING Voltage
V
ov
OV
tr
VBAT V
). This requirement is expressed in
=
and V
I
LIM
≥
×
CM
tr
(
R
+
.)
w
V
×
CM
L
w
+
+
V
R
OV
ph
tr
) in the off-hook
)
Rev. 0.1
When VBLO can no longer satisfy Equation 11, VBHI
must be selected.
Since the battery switching mechanism monitors the dc
voltage at the RING terminal (TIP in reverse active
mode), and the RING voltage with respect to system
GND already includes V
obtained from Equation 13.
The RAM locations, BATHTH and BATLTH, can assume
any value in the range from 0 to 160.2 in Volts. One LSB
of BATHTH or BATLTH is 628 mV. The values for
BATHTH and BATLTH occupy bits 7 through 14 in their
corresponding RAM locations and must be shifted up by
7 bit positions, hence the multiplication by 2
Equations 14 and 15.
Equations 14 and 15 provide a means of calculating
BATHTH and BATLTH, which provides for two LSBs of
hysteresis (2 x 0.628 = 1.256V).
The value of BATLPF is obtained from Equation 16,
where f is the desired cut-off frequency for the low-pass
filter. BATLPF occupies bits 3 through 15 and must be
shifted up 3 bit positions, hence the multiply by 2
Equation 16. Typically, f is set to 10 Hz, which yields
BATLPF = 0xA10.
Power Offload Tool
This application note is bundled with an Excel file titled
“Si3200_power_calc.xls”.
The bundled Excel file provides a very useful tool for
analyzing the power dissipation of the Si3200 as a
function of loop length and other user-entered
parameters. The user enters the desired values for the
various parameters at the top of the worksheet and the
Equation 13.Battery Switching Threshold Voltage
BATLPF
BATHTH
BATLTH
=
Equation 14.BATHTH
Equation 15.BATLTH
Equation 16.BATLPF
V
2
thres
=
=
3
2
× EC2HEX
2
7
7
D
×
=
×
CM
DEC2HEX
DEC2HEX
VBLO
, the switching threshold is
–


2
--------------------------------------- -
V


×


OV
V
--------------- -
0.628
V
--------------- - 1
0.628
π
thres
thres
×
800
f
×
+
–
4096
AN91
1






7
3
in
in
5