SI3225-G-GQ Silicon Laboratories Inc, SI3225-G-GQ Datasheet - Page 46

• 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
3.11. Ground Key Detection
Ground key detection detects an alerting signal from the
terminal equipment during the tip open or ring open
linefeed states. The functional blocks required to
implement a ground key detector are shown in
Figure 22 on page 48, and the register set for detecting
a ground key event is provided in Table 28 on page 49.
The primary input to the system is the longitudinal
current sense value provided by the voltage/current/
power monitoring circuitry and reported in the ILONG
RAM address. The I
provided the LFS bits in the linefeed register indicate
the device is in the tip open or ring open state.
The longitudinal current (I
in the following equation. Refer to Figure 18 on page 38
for the transistor references used in the equation (Q1,
Q2, Q5, and Q6—note that the Si3200/2 has
corresponding MOS transistors). The same I
equation applies to the discrete bipolar linefeed as well
as the Si3200/2 linefeed device.
46
Loop Closure Interrupt
Pending
Loop Closure Interrupt Enable
Linefeed Shadow
Loop Closure Detect Status
Loop Closure Detect Debounce
Interval
Loop Current Sense
Loop Closure Threshold
(on-hook to off-hook)
Loop Closure Threshold
(off-hook to on-hook)
Loop Closure Filter Coefficient
Loop Closure Mask Interval
Notes:
1. The effective I
2. The usable range for LCRONHK and LCROFFHK is limited to 61 mA. Entering a value > 61 mA will disable threshold
detection.
Parameter
I
Table 25. Register and RAM Locations Used for Loop Closure Detection
LONG
LOOP
LONG
=
I
--------------------------------------------------- -
Q1
resolution is approximately 500 µA.
LONG
value is produced in the ISP
–
I
Q6
) is computed as shown
–
2
I
Q5
Register/RAM
LCROFFHK
Mnemonic
LINEFEED
LCRONHK
LCRMASK
+
IRQVEC2
LCRRTP
LCRLPF
IRQEN2
LCRDBI
I
ILOOP
Q2
LONG
Register/RAM Bits
LCROFFHK[15:0]
LCRONHK[15:0]
LCRMASK[15:0]
Rev. 1.3
LCRLPF[15:3]
LCRDBI[15:0]
ILOOP[15:0]
LFS[2:0]
LOOPS
LOOPE
LCR
The output of the ISP (I
programmable, digital low-pass filter, which removes
unwanted ac signal components before threshold
detection.
The low-pass filter coefficient is calculated using the
following equation and is entered into the LONGLPF
RAM location:
Where f = the desired cutoff frequency of the filter.
The programmable range of the filter is from 0h (blocks
all signals) to 4000h (unfiltered). A typical value of 10
(0A10h) is sufficient to filter out any unwanted ac
artifacts while allowing the dc information to pass
through the filter.
The output of the low-pass filter is compared to the
programmable threshold, LONGHITH. Hysteresis is
enabled
LONGLOTH, to detect when the ground key is released.
The threshold comparator output feeds a programmable
debounce filter.
by
LONGLPF
0 to 101.09 mA
0 to 101.09 mA
Programmable
Monitor only
Monitor only
0 to 40.96 s
programming
101.09 mA
0 to 40.96s
0 to 4000h
50.54 to
Yes/No
Yes/No
Range
=
(
-------------------------------- -
2
2
2πf 4096
LONG
800
×
LSB Size
3.097 µA
3.097 µA
3.097 µA
a
1.25 ms
1.25 ms
) is the input to a
N/A
N/A
N/A
N/A
N/A
second
)
×
2
3
Resolution
Effective
396.4 µA
396.4 µA
1.25 ms
500 µA
1.25 ms
threshold,
N/A
N/A
N/A
N/A
N/A
1