Si3056
Si3018/19/10
2
3
4
1
Off-Hook Counter
and Calibration
(402.75 ms nominally)
CAS Tone
Received
LINE
Off-Hook Counter
(8 ms)
On-Hook
Off-Hook
On-Hook
Off-Hook
Ack
FOH[1] Bit
FOH[0] Bit
RCALD Bit
CALD Bit
OH Bit6
Notes:
1. The off-hook counter and calibrations prevent transmission or reception of data for 402.75 ms (default) for the line
voltage to settle.
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 transmitted on the SDO pin.
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, then the automatic calibrations are not performed.
5. After allowing the off-hook counter to expire (8 ms), normal transmission and reception can continue. If CID data
reception is required, send the appropriate signal to the CO at this time.
6. This example uses the OH bit to put the Si3056 into an off-hook state. The OFHK pin can also be used to accomplish
this. To use the OFHK pin instead of the OH bit, simply enable the OHE bit (Register 5, bit 1) and drive the OFHK pin
low during the preceding sequence. This has the same effect as setting the OH bit.
Figure 23. Implementing Type II Caller ID on the Si3056
34
Rev. 1.05
SILICON [ SILICON ]
