SI3215-FT Silicon Laboratories Inc, SI3215-FT Datasheet - Page 33

• Manufacturer Part Number: SI3215-FT
• Description: IC SLIC/CODEC 1CH 38TSSOP
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3215-FT

• Function: Subscriber Line Interface Concept (SLIC), CODEC
• Interface: PCM, SPI
• Number Of Circuits: 1
• Voltage - Supply: 3.13 V ~ 5.25 V
• Current - Supply: 88mA
• Power (watts): 700mW
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: *
• Includes: Audio Tone Generation, BORSCHT Functions, FSK Generation, Voice Loopback Test Modes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2.4.2. Oscillator Frequency and Amplitude
Each of the two-tone generators contains a two-pole
resonate
frequency and amplitude, which are programmed via
indirect registers OSC1, OSC1X, OSC1Y, OSC2,
OSC2X, and OSC2Y. The sample rate for the two
oscillators is 16 kHz. The equations are as follows:
where f
where desired Vrms is the amplitude to be generated;
n = 1 or 2 for oscillator 1 or oscillator 2, respectively.
For example, in order to generate a DTMF digit of 8, the
two required tones are 852 Hz and 1336 Hz. Assuming
the generation of half-scale values (ignoring twist) is
desired, the following values are calculated:
OSC1X
OSCnX
n
OSC1
is the frequency to be generated;
=
=
oscillator
coeff
1
-- -
4
1
-- -
4
Counter
×
Modulo
×
coeff
8 kHz
Clock
16-Bit
OATn
=
OITn
*Tone Generator 1 Only
OSCn = coeff
1
0.05545
-------------------- -
1.94455
----------------------- -
1
1 coeff
0.94455 2
n = "1" or "2" for Tone Generator 1 and 2, respectively
–
+
=
n
coeff
= cos(2 π f
OATnE
cos
OITnE
OSCnY = 0,
OSC1Y = 0
circuit
⎛
⎝
(
×
2π852
---------------- -
16000
×
(
15
Expire
Expire
2
OnE
(
OAT
OIT
2
)
15
15
n
=
with
n
–
⎞
⎠
x (2
/16 kHz),
–
Figure 18. Simplified Tone Generator Diagram
1
30951
1
=
)
Cross
Logic
)
×
Zero
15
0.94455
×
Logic
Logic
0.5
INT
INT
a
);
Desired V
------------------------------------ -
=
OZn
1.11 V
=
78E6h
programmable
692
Zero Cross
OSSn
OnAE
OnAP
Load
Logic
OnIE
rms
OnIP
=
rms
2B3h
REL*
Rev. 0.92
Register
Enable
Load
Resonance
The computed values above would be written to the
corresponding registers to initialize the oscillators. Once
the oscillators are initialized, the oscillator control
registers can be accessed to enable the oscillators and
direct their outputs.
2.4.3. Tone Generator Cadence Programming
Each of the two tone generators contains two timers,
one for setting the active period and one for setting the
inactive period. The oscillator signal is generated during
the active period and suspended during the inactive
period. Both the active and inactive periods can be
programmed from 0 to 8 seconds in 125 µs steps. The
active period time interval is set using OAT1 (direct
registers 36 and 37) for tone generator 1 and OAT2
(direct registers 40 and 41) for tone generator 2.
To enable automatic cadence for tone generator 1,
define the OAT1 and OIT1 registers and then set the
O1TAE bit (direct Register 32, bit 4) and O1TIE bit
(direct Register 32, bit 3). This enables each of the
timers to control the state of the Oscillator Enable bit,
O1E (direct Register 32, bit 2). The 16-bit counter will
begin counting until the active timer expires, at which
time the 16-bit counter will reset to zero and begin
Two-Pole
Oscillator
OSC2X
16 kHz
Clock
OSCnX
OSCnY
OSCn
OSC2 = 0.86550 (2
=
coeff
1
-- -
4
×
2
0.13450
-------------------- -
1.86550
=
cos
OSC2Y = 0
Routing
⎛
⎝
Signal
×
2π1336
------------------- -
16000
(
15
2
15
) = 28361 = 6EC8h
–
OnSO
1
⎞
⎠
)
=
×
0.5
0.86550
to TX Path
to RX Path
=
Si3215
1098
=
44Bh
33