SI2438FT18-EVB Silicon Laboratories Inc, SI2438FT18-EVB Datasheet - Page 37
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SI2438FT18-EVB
Manufacturer Part Number
SI2438FT18-EVB
Description
BOARD EVAL SI2438+SI3018 24PIN
Manufacturer
Silicon Laboratories Inc
Datasheet
1.SI3050-E-FM.pdf
(128 pages)
Specifications of SI2438FT18-EVB
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Notes:
5.26. Overload Detection
The Si3050 can be programmed to detect an overload
condition that exceeds the normal operating power
range of the DAA circuit. To use the overload detection
feature, the following steps should be followed:
1. Set the OH bit (Register 5, bit 0) to go off-hook, and
2. Enable overload detection by then setting the OPE
If the DAA senses an overload situation it automatically
RCALD Bit
FOH[1] Bit
FOH[0] Bit
CALD Bit
1. The off-hook counter and calibrations prevent transmission or reception of data for 402.75 ms (default) for the line
2. The caller alert signal (CAS) tone transmits from the CO to signal an incoming call.
3. The device is taken on-hook to read the line voltage in the LVS bits to detect parallel handsets. In this mode, no data is
4. When the device returns off-hook, the normal off-hook counter is reduced to 8 ms. If the CALD and RCALD bits are set,
5. After allowing the off-hook counter to expire (8 ms), normal transmission and reception can continue. If CID data
wait 25 ms to allow line transients to settle.
bit (Register 17, bit 3).
f. Set the OH bit to return to an off-hook state.
OH Bit
Immediately after returning to an off-hook state,
the off-hook counter must be allowed to expire.
This allows the line voltage to settle before
transmitting or receiving data. After 8 ms normal
data transmission and reception can begin. If a
non-compliant parallel device is present, then a
reply tone is not sent by the host tone generator
and the CO does not send the CID data. If all
devices on the line are Type II CID compliant,
then the host must mute its upstream data output
to avoid the propagation of its reply tone and the
subsequent CID data. When muting its upstream
data output, the host processor should return an
acknowledgement (ACK) tone to the CO
requesting transmission of CID data.
voltage to settle.
transmitted on the DTX pin.
then the automatic calibrations are not performed.
reception is required, send the appropriate signal to the CO at this time.
LINE
On-Hook
Figure 26. Implementing Type II Caller ID on the Si3050+Si3011/19
(402.75 ms nominally)
Off-Hook Counter
and Calibration
1
Of f -Hook
Rev. 1.4
3. The CO then responds with CID data after receiving
4. The muting of the upstream data path by the host
5. The CALD and the RCALD bits can be cleared to
Because of the nature of the low-power ADC, the data
presented on DTX can have up to a 10% dc offset. The
caller ID decoder must either use a high-pass or a
band-pass filter to accurately retrieve the caller ID data.
presents an 800 impedance to the line to reduce the
hookswitch current. At this time, the DAA also sets the
OPD bit (Register 19, bit 0) to indicate that an overload
condition exists. The line current detector within the
DAA has a threshold that is dependent on the ILIM bit
(Register 26). When ILIM = 0, the overload detection
threshold equals 160 mA. When ILIM = 1, the overload
detection threshold equals 60 mA. The OPE bit should
always be cleared before going off-hook.
CA S Tone
Received
the CID data, the host processor unmutes the
upstream data output and continues with normal
operation.
processor mutes the handset in a telephone
application so the user cannot hear the
acknowledgement tone and CID data being sent.
re-enable the automatic calibrations when going
off-hook. The FOH[1:0] bits also can be programmed
to 01 to restore the default off-hook counter time.
Si3050 + Si3011/18/19
2
On-Hook
3
Off-Hook Counter
(8 ms)
4
Of f -Hook
A ck
5
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