SI3200-FS Silicon Laboratories Inc, SI3200-FS Datasheet - Page 6

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

Specifications of SI3200-FS

• Package / Case: 16-SOIC (3.9mm Width)
• 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
• Includes: Battery Switching, BORSCHT Functions, DTMF Generation and Decoding, FSK Tone Generation, Modem and Fax Tone Detection
• Product: SLIC
• Supply Voltage (min): 3.13 V
• Supply Current: 0.11 mA, 8.8 mA
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Number Of Channels: 2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN91
worksheet calculates and displays the power limit for
the Si3200 and the power dissipated in the Si3200 as a
function of loop length. The worksheet also takes care
of calculating the battery switching voltage threshold
between VBLO and VBHI so that the displayed power
dissipation takes into consideration which is the
applicable battery supply (VBLO or VBHI), depending
on loop length.
The Si3200_power_calc.xls file should be used to fine
tune the optimal low battery voltage (VBLO) such that
the power dissipation in the Si3200 will remain under
P
Step-by-Step Procedure
Perform the following steps:
1. Determine the value of all parameters required in Table 1.
2. Using the application’s required maximum ambient
3. Calculate the optimal VBLO using Equation 5 initially using
4. Determine the appropriate resistor value (Equations 6 and
5. Calculate the correct values for BATHTH, BATLTH and
Typical Design Example
Perform the following steps:
1. Determine The value of all parameters required in Table 1.
6
d(max)
temperature, calculate the maximum allowable power
dissipation for the Si3200 (Equation 1).
k = 0.80. To arrive at the optimal value for VBLO, it may be
necessary to perform several iterations while using the
Power Calculation Tool until a value of VBLO that results in
P
7) or select the appropriate Zener diode and transistor
(Equations 8, 9, and 10). Verify the power dissipation in the
transistor and Zener diode and corresponding thermal
management.
BATLPF using Equations 13, 14, 15, and 16.
An application has the requirements shown in Table 3:
Si3200
for all applicable loop lengths.
< P
d(max)
for all loop lengths is obtained.
Rev. 0.1
2. Using the application’s required maximum ambient
P
3. Calculate the optimal VBLO using Equation 5 and k = 0.80
VBLO = (0.80 x 1 + 200 x 0.020625
0.004) = 35.94 V (round to 36 V)
Use the Power Calculation Tool to verify the value of
VBLO = –36 V satisfies P
required loop lengths:
The Si3200 Power Calculation Tool yields the result
shown in Figure 3, which is clearly acceptable as the
power dissipation for the Si3200 remains well under
1 W as required for an ambient temperature of 85 °C.
The discontinuity in the P
corresponds to the point at which battery switching
occurs. Below approximately 13500 feet, VBLO is used,
and for longer loop lengths, VBHI is used. Note that the
maximum power for the VBLO segment, which occurs
at zero loop length, is approximately equal to the
maximum power for the VBHI segment. When using the
Power Calculation Tool, it is desirable to equalize these
two peak powers by optimizing the value of the derived
VBLO.
4. Determine the appropriate resistor value (Equations 6 and
For resistive offload:
R
standard 5% value is 820 Ω).
P
Parameter
Maximum Ambient
Temperature
Loop Current (ILIM)
Bias Current (SBIAS)
Telephone DC
Resistance (typ)
Maximum Loop Length
Wire Resistance per
Foot
Battery Supply Voltage
Overhead Voltages
(V
d(max)
offload
offload
CM
temperature, calculate the maximum allowable power
dissipation for the Si3200 (Equation 1):
(20% margin).
7) or select the appropriate Zener diode and transistor
(Equations 8, 9, and 10):
+ V
= 820 Ω x (24.625 mA)
= (56 V – 36 V) / 24.625 mA = 812 Ω (nearest
= (140 °C – 85 °C) / 85 °C/W = 1 W
Table 3. System Requirements
OV
)
Symbol
L
Si3200
(max)
VBHI
w (max)
I
R
V
I
R
bias
Ta
lim
2
Si3200
ph
oh
w
= 497mW
< Pd(max) for all
20.625
18000
Value
line of Figure 3
2
0.09
200
–56
) / (0.020625 +
85
4
7
Ω/foot
Units
mA
mA
°C
Ω
V
V
ft