SI3206-B-GQ Silicon Laboratories Inc, SI3206-B-GQ Datasheet - Page 34

• Manufacturer Part Number: SI3206-B-GQ
• Description: IC PROSLIC LINE FEED 125V 48TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3206-B-GQ

• On-hook Transmission: Yes
• Polarity Reversal: Yes
• On-chip Ring Relay Driver: Yes
• Longitudinal Balanced: 63
• Operating Supply Voltage (typ): 3.3V
• Operating Temp Range: -40C to 85C
• Package Type: TQFP
• Loop Current Limit: 45mA
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Function: Subscriber Line Interface Concept (SLIC)
• Interface: GCI, PCM, SPI
• Number Of Circuits: 4
• Voltage - Supply: 3.3V
• Current - Supply: *
• Power (watts): *
• Operating Temperature: *
• Mounting Type: Surface Mount
• Package / Case: 48-TQFP Exposed Pad
• Includes: *
• Lead Free Status / RoHS Status: Compliant

Si3232
4.5.2. 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 15, and the register set for detecting a ground
key event is provided in Table 22 on page 36. 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 11 on page 26
for the transistor references used in the equation (Q1,
Q2, Q5 and Q6 – note that the Si3200 has
corresponding MOS transistors). The same I
equation applies to the discrete bipolar linefeed as well
as the Si3200 linefeed device.
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.
34
by
LONGLPF
I
LONG
programming
LONG
=
value is produced in the ISP
I
--------------------------------------------------- -
=
Q1
LONG
–
(
-------------------------------- -
2πf 4096
I
LONG
Q6
800
×
) is computed as shown
–
2
a
I
Q5
) is the input to a
second
+
)
I
Q2
×
2
3
threshold,
Preliminary Rev. 0.96
LONG
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.
As an example of ground key detection, suppose that
the Si3220/25 has been programmed with the current
values shown in Table 20.
With the settings of Table 20, the behavior of I
I
Table 21. 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 21 is the automatic
transition from TIP-OPEN to FWD-ACTIVE in response
to LCR = 1.
LONG
Table 20. Settings for Ground Key Example
, LCR, LONGHI, and CMHIGH is as shown in
LONG
is used to generate the LONGHI status bit,
LONGLOTH
LCROFFHK
LONGHITH
LCRONHK
ILIM
21 mA
14 mA
10 mA
7 mA
5 mA
LOOP
,