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Rev. 1.4
115
U66 (DAAC5) is a bit-mapped register with all bits except bit 6 reserved (see Table 77).
Bit 6 (FDT) is a read-only bit that reports whether or not an isolation capacitor frame lock is established. FDT is
typically used for board-level debugging and is not used during normal modem operation.
U66 resets to 0xXX40 with a power-on or manual reset assuming framelock is established. The upper byte is
variable.
5.7.17. U67–U6A (International Configuration Registers)
International Configuration Registers include U67 through U6A. These are bit-mapped registers that control
international configuration settings, such as dc and ac termination, ringer impedance and detection, current limit,
and billing tone protection.
U67 is a bit-mapped register with bits 5:4, 8, 11:10, and 15:14 reserved (see Table 78). U67 resets to 0x0008 with
a power-on or manual reset.
Bits 13:12 (MINI) adjust the minimum loop current at which the DAA can operate. The MINI bits generally have no
effect on the TX level and RX sensitivity as long as there is sufficient loop current. However, as the loop current is
reduced and approaching the limit, the TX level will begin to drop nonlinearly. The nonlinear region is about 2 mA
or so within the limit, the amount of drop varies with different MINI settings. In the worst case MINI=00 and the
current is 10 mA, the drop is about 4 dB. In the best case MIN=00 and the current is 16 mA, the drop is about
0.5dB.
It is not recommended that customers adjust U52 or U46 to compensate for this TX drop. Unlike the case of DCV,
there is no distinctive level shift except for this nonlinear region. Furthermore, the host only knows it is near this
nonlinear region is by reading loop current. Since the LCS accuracy is 1.1mA and this nonlinear region is roughly
2 mA, it is impossible for the customer to accurately compensate for the TX level.
There is no practical need to compensate for the level. In a real world application, the loop current is at least a few
mA above MINI. For example, setting MINI=00, DCV=00 for the Australian AS/ACIF S002:2001 specification, the
loop current is 13mA; this is 3mA away from MINI and the DAA is still in the linear range.
Bit 7 (DCR) is used to set the dc line termination of the modem. DCR = 0 is the normal mode of operation with dc
impedance selected by U67 [3:2] (DCV).
Table 76. U65 Bit Map
Bit
Name
Function
15
Reserved
Read returns zero.
14
PWMG
PWM gain.
0
=
No gain.
1 = 6 dB gain applied to AOUT.
13
PDN
Power Down.
0
=
Normal.
1 = Power Down.
12:7
Reserved Read returns zero.
6:5
Reserved
Do not change (use read-modify-write).
4
PDL
Line-Side Chip Power Down.
0
=
Normal operation.
1 = Places the Si3018/10 in Power-Down mode.
3:2
Reserved Read returns zero.
1:0
Reserved
Do not change (use read-modify-write).
Содержание Si2404
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Страница 200: ...AN93 200 Rev 1 4 Figure 31 TAM Handset and Speakerphone Voice Paths ...
Страница 201: ...AN93 Rev 1 4 201 Figure 32 Si3000 Codec Gain and Signal Selection Options ...
Страница 290: ...AN93 290 Rev 1 4 Figure 57 256 Band Spectral Display Figure 58 2048 Band Spectral Display ...
Страница 305: ...AN93 Rev 1 4 305 Figure 76 Parallel or SPI Port Interrupt Service Flowchart ...