SI2414 SILABS [Silicon Laboratories], SI2414 Datasheet - Page 68

• Manufacturer Part Number: SI2414
• Manufacturer: SILABS [Silicon Laboratories]

Si2456/Si2433/Si2414
DC Termination
The
termination modes that are selected with DCT (U67,
bits 3:2).
FCC mode (DCT = 10), shown in Figure 9, is the default
dc termination mode and supports a transmit full-scale
level of –1 dBm at TIP and RING. This mode meets
FCC requirements in addition to the requirements of
many other countries.
CTR21 mode DCT = 11, shown in Figure 10, provides
current limiting while maintaining a transmit full-scale
level of –1 dBm at TIP and RING. The dc termination
current limits before reaching 60 mA.
68
Figure 10. CTR21 Mode I/V Characteristics
Figure 9. FCC Mode I/V Characteristics
Si2456/33/14
20
45
40
35
30
25
15
10
5
12
11
10
.015 .02 .025 .03 .035 .04 .045 .05 .055 .06
8
9
7
6
.01 .02 .03 .04 .05 .06 .07 .08 .09 .1 .11
CTR21 DCT M ode
Loop Current (A )
has
Loop Current (A )
FCC DCT M ode
four
programmable
Rev. 0.9
dc
Japan mode DCT = 01, shown in Figure 11, is a lower
voltage mode and supports a transmit full-scale level of
–2.71 dBm. Higher transmit levels for DTMF dialing are
also supported. See "DTMF Dialing" on page 69. The
low voltage requirement is dictated by countries, such
as Japan and Malaysia.
Low Voltage mode (DCT = 00), shown in Figure 12, is
the lowest line voltage mode supported on the Si2456/
33/14 with a transmit full-scale level of –5 dBm. Higher
transmit levels for DTMF dialing are also supported.
See "DTMF Dialing" on page 69. This low-voltage mode
is offered for situations that require very low line voltage
operation. It is important to note that this mode should
only be used when necessary because the dynamic
range is significantly reduced, and, thus, the ISOmodem
is not able to transmit or receive large signals without
clipping them.
Figure 11. Japan Mode I/V Characteristics
10.5
10.5
9.5
8.5
7.5
6.5
5.5
9.5
8.5
7.5
6.5
5.5
10
10
Figure 12. Low Voltage Mode I/V
8
8
9
7
6
9
7
6
.01 .02 .03 .04 .05 .06 .07 .08 .09 .1 .11
.01 .02 .03 .04 .05 .06 .07 .08 .09 .1 .11
Characteristics
Low V oltage M ode
Japan DCT M ode
Loop Current (A )
Loop Current (A )