SI3225-G-GQ Silicon Laboratories Inc, SI3225-G-GQ Datasheet - Page 68

• 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

Si3220/25 Si3200/02
3.22. Pulse Metering Generation
The Si3220 offers an additional tone generator to
generate tones above the audio frequency band. This
oscillator generates billing tones that are typically
12 kHz or 16 kHz. The generator follows the same
algorithm as described in "3.20.1. Tone Generator
Architecture" on page 63 with the exception that the
sample rate for computation is 64 kHz instead of 8 kHz.
The equation is as follows:
where Full Scale V
68
Parameter
Pulse Metering Frequency
Coefficient
Pulse Metering Amplitude
Coefficient
Pulse Metering Attack/Decay
Ramp Rate
Pulse Metering Active Timer
Pulse Metering Inactive Timer
Pulse Metering, Control
Interrupt
Pulse Metering AGC
Amplitude Threshold
PM Waveform Present
PM Active Timer Enable
PM Inactive Timer Enable
Pulse Metering Enable
PMAMPL
=
PMFREQ
Table 38. Register and RAM Locations Used for Pulse Metering Generation
1
-- - 1 coeff
4
Coeff
----------------------- -
1
–
+
PK
coeff
=
= 0.5 V.
=
cos
coeff
×
⎛
⎝
(
------------------------- -
64000 Hz
2
15
×
2πf
–
(
2
1
14
)
×
–
⎞
⎠
--------------------------------------- -
FullScale V
IRQVEC1, IRQEN1
1
Desired V
PMTALO/PMTAHI
PMTILO/PMTIHI
)
Register/RAM
Mnemonic
PMAMPTH
PMFREQ
PMRAMP
PMAMPL
PMCON
PMCON
PMCON
PMCON
PK
PK
Rev. 1.3
The pulse metering oscillator has a volume envelope
(linear ramp) on the on/off transitions of the oscillator.
The ramp is controlled by the value in the PMRAMP
RAM address, and the sinusoidal generator output is
multiplied by this volume before it is sent to the pulse
metering DAC. The volume value is incremented by the
value in PMRAMP at an 8 kHz rate. The volume will
ramp from 0 to 7FFF in increments of PMRAMP to allow
the value of PMRAMP to set the slope of the ramp. The
clip detector stops the ramp once the signal seen at the
transmit path exceeds the amplitude threshold set by
PMAMPTH, which provides an automatic gain control
(AGC) function to prevent the audio signal from clipping.
When the pulse metering signal is turned off, the
volume ramps down to 0 by decrementing according to
the value of PMRAMP. Figure 38 illustrates the
functional blocks involved in pulse metering generation,
and Table 38 presents the required register and RAM
locations that must be set to generate pulse metering
signals.
PMAMPTH[15:0]
PMRAMP[15:0]
PULSETA[15:0]
PMFREQ[15:3]
PMAMPL[15:0]
PULSETI[15:0]
Register/RAM
PULSTAE,
PULSTAS,
PULSTIE,
PULSTIS
ENSYNC
PULSE1
TAEN
TIEN
Bits
Interrupt Status and control
Sets oscillator frequency
Sets oscillator amplitude
Indicates signal present
Description/Range
0 to 8.19 s (125 µs)
0 to 8.19 s (125 µs)
(full amplitude)
Enable/disable
Enable/disable
Enable/disable
0 to PMAMPL
0 to 500 mV
(LSB Size)
registers