SI3232-BQ Silicon Laboratories Inc, SI3232-BQ Datasheet - Page 33

• Manufacturer Part Number: SI3232-BQ
• Description: IC SLIC PROG DUAL-CH 64TQFP
• Manufacturer: Silicon Laboratories Inc

Specifications of SI3232-BQ

• Package / Case: *
• Function: Subscriber Line Interface Concept (SLIC)
• Interface: ISDN
• Number Of Circuits: 2
• Voltage - Supply: 3.13 V ~ 3.47 V
• Current - Supply: 28mA
• Power (watts): 280mW
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Product: SLIC
• Supply Voltage (min): 3.13 V
• Supply Current: 28 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Number Of Channels: 2
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Ground Key Detection
Ground key detection is used to detect an alerting signal
from the terminal equipment during the Active linefeed
state (forward or reverse polarity). 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 20. 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
ILONG value is processed in the input signal processor
(ISP) provided the LFS bits in the Linefeed register
indicate the device is in an Active state. The output of
the ISP is the input to a programmable digital low-pass
filter, which can be used to remove unwanted ac signal
components before threshold detection.
The low-pass filter coefficient is calculated using the
equation below and is entered into the LONGLPF RAM
location.
LONGLPF = [(2
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. I
2. The usable range for LCRONHK and LCROFFHK is limited to 61 mA. Entering a value >61 mA disables threshold
500 µA.
detection.
LOOP
Parameter
is a calculated value based on measured I
Table 19. Register and RAM Locations used for Loop Closure Detection
π
f x 4096)/800] x 2
3
Mnemonic
LCROFFHK
LINEFEED
LCRONHK
Register/
LCRMASK
IRQVEC2
LCRRTP
LCRLPF
IRQEN2
LCRDBI
ILOOP
RAM
Preliminary Rev. 0.95
Q1
LCROFFHK[15:0]
Register/RAM
LCRONHK[15:0]
LCRMASK[15:0]
–I
LCRLPF[15:3]
LCRDBI[15:0]
ILOOP[15:0]
Q4
LFS[2:0]
LOOPS
LOOPE
currents. The resulting effective resolution is approximately
Bits
Where f is the desired cutoff frequency of the filter.
The programmable range of the filter is from 0 (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 a
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 has been satisfied,
the LONGHI bit is set to indicate that a valid loop
closure has occurred.
LCR
by
Programmable
0 to 101.09 mA
0 to 101.09 mA
0 to 101.09 mA
Monitor only
Monitor only
0 to 40.96 s
0 to 40.96 s
programming
0 to 4000h
Range
Yes/No
Yes/No
2
2
3.097 µA
3.097 µA
3.097 µA
a
1.25 ms
1.25 ms
LSB
Size
N/A
N/A
N/A
N/A
N/A
second
Si3232
Resolution
396.4 µA
396.4 µA
500 µA
1.25 ms
1.25 ms
threshold,
N/A
N/A
N/A
N/A
N/A
1
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