SI3220-FQ Silicon Laboratories Inc, SI3220-FQ Datasheet - Page 44

• Manufacturer Part Number: SI3220-FQ
• Description: IC SLIC/CODEC DUAL-CH 64TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3220-FQ

• 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: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: *
• Includes: Battery Switching, BORSCHT Functions, DTMF Generation and Decoding, FSK Tone Generation, Modem and Fax Tone Detection
• Product: Telecom
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Si3220/Si3225
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. The output of the debounce filter
remains in its present state unless the input remains in
the opposite state for the entire period of time
programmed by the loop closure debounce interval,
LONGDBI. If the debounce interval is satisfied, the
LONGHI bit is set to indicate that a valid ground key
event has occurred.
When the Si3220/25 detects a ground key event, the
linefeed automatically transitions from the TIP-OPEN
(or RING-OPEN) state to the FORWARD-ACTIVE (or
REVERSE-ACTIVE) state. However, this automatic
state transition is triggered by the LCR bit becoming
active (i.e., =1), and not by the LONGHI bit.
While I
a transition from TIP-OPEN to the FORWARD-ACTIVE
state (or from the RING-OPEN to the REVERSE-
ACTIVE state) occurs when the RING terminal (or TIP
terminal) is grounded and is based on the LCR bit and
implicitly on exceeding the LCROFFHK threshold.
44
LONG
#
1
2
3
4
5
by
is used to generate the LONGHI status bit,
LOOP CLO-
RING-GND
RING-GND
programming
OPEN
OPEN
LOOP
SURE
LOOP
Loop
State
Table 26. State Transitions During Ground Key Detection
(FWD-ACTIVE)
(FWD-ACTIVE)
(FWD-ACTIVE)
(TIP-OPEN)
(TIP-OPEN)
LINEFEED
a
LFS = 3
LFS = 3
LFS = 1
LFS = 1
LFS = 1
State
second
threshold,
I
(mA)
LOOP
22
22
21
0
0
Rev. 1.0
As an example of ground key detection, suppose that
the Si3220/25 has been programmed with the current
values shown in Table 25.
With the settings of Table 25, the behavior of I
I
Table 26. The entries under “Loop State” indicate the
condition of the loop, as determined by the equipment
terminating the loop. The entries under “LINEFEED
Setting” indicate the state initially selected by the host
CPU (e.g., TIP-OPEN) and the automatic transition to
the FORWARD-ACTIVE state due to a ground key
event (when RING is connected to GND). The transition
from state #2 to state #3 in Table 26 is the automatic
transition from TIP-OPEN to FWD-ACTIVE in response
to LCR = 1.
LONG
Table 25. Settings for Ground Key Example
I
(mA)
LONG
, LCR, LONGHI, and CMHIGH is as shown in
–11
–11
0
0
0
LCR
LONGLOTH
LCROFFHK
LONGHITH
LCRONHK
0
1
1
1
0
ILIM
LONGHI
0
1
1
0
0
21 mA
14 mA
10 mA
7 mA
5 mA
CMHIGH
0
0
1
0
0
LOOP
,