SI2493-C-FT Silicon Laboratories Inc, SI2493-C-FT Datasheet - Page 81

• Manufacturer Part Number: SI2493-C-FT
• Description: 56 KBPS, V.92 ISOMODEM SYSTEM-SIDE - LEAD-FREE TSSOP 0 TO 7
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-C-FT

• Mfg Application Notes: SI2493/57/34/15/04, Appl Note AN93
• Data Format: V.21, V.22, V.23, V.29, V.32, V.34, V.90, V.92, Bell 103, Bell 212A
• Baud Rates: 56k
• Interface: Parallel
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.3.19. U49–U4C (Ring Detect Registers)
U49, U4A, U4B, and U4C set a representation of the
maximum ring frequency, the difference between the
highest and lowest valid ring frequency, minimum ring
on time, and maximum ring cadence time (time on +
time off), respectively. U49 is set as the hexadecimal
equivalent of 2400 divided by the highest valid ring
frequency in Hz.
3.3.20. U4D (Modem Control Register 1—MOD1)
U4D is a bit-mapped register that controls various
telephony functions including the enabling of calling and
guard tones and loop current verification prior to dialing.
All bits in this register are read/write except the reserved
bits, 15, 13, 9, 6, 2, and 0. These bits must not be
written with a logic 1, and reading them returns a value
of 0 (see Table 42).
Bit 14 (TOCT) = 0 (default) turns off Calling Tone after
Answer Tone detection and allows Calling Tone
cadence to complete before proceeding with connect
sequence (per V.25). TOCT = 1 turns off Calling Tone
200 ms after Answer Tone detection begins.
Bit 12 (NHFP) = 0 (default) disables hook-flash during
pulse dialing (ignores & and ! dial modifiers). NHFP = 1
enables hook-flash during pulse dialing.
Bit 11 (NHFD) = 0 (default) disables hook-flash during
dial string (tone or pulse). NHFD = 1 enables hook-flash
during (tone or pulse) dial string.
Bit 10 (CLPD) = 0 (default) Modem ignores loop current
prior to dialing. If CLPD = 1, modem measures loop
current prior to dialing.
Register
U4A
U4B
U4C
U49
RGMN
RGNX
RGFH
RGFD
Name
Ring frequency high (2400/maximum valid ring frequency in Hz).
Ring frequency delta (2400/minimum valid ring frequency in Hz)—
(2400/maximum valid ring frequency in Hz).
Ring cadence minimum ON time in seconds multiplied by 2400.
Ring cadence maximum total time in seconds multiplied by 2400.
Table 41. Ring Detect Registers
Rev. 0.9
Description
U4A is set as the hexadecimal equivalent of 2400
divided by the minimum valid ring frequency in Hertz
minus 2400 divided by the maximum valid ring
frequency in Hertz.
U4B and U4C are set as the hexadecimal equivalents of
the times in seconds multiplied by 2400. The default
high ring frequency, RGFH (U49), is 70.6 Hz. The
default ring cadence minimum on time, RGMN, is
250 ms. The default ring cadence maximum total time is
11 seconds.
This bit is used in conjunction with the loop current
debounce registers, U50 and U51 (LCDN and LCDF),
and U4D bit 1 (LLC). U50 provides a delay between the
modem
measurement. The delay allows the loop current to
stabilize prior to the measurement. Some countries
require the presence of loop current prior to dialing.
Bit 8 (FTP) = 0 (default) allows mixing tone and pulse
dialing in a single AT command. FTP = 1 forces the first
dialing mode encountered (tone or pulse) for the entire
AT command.
Bit 7 (SPDM) = 0 (default) causes the modem to pulse
dial if an ATDP command is given. If this bit is set to 1
the pulse dial modifier, P, is ignored, and the dial
command is carried out as a tone dial (ATDT).
Bit 5 (GT18) = 0 (default) disables the 1800 Hz Guard
tone. GT18 = 1 enables the 1800 Hz Guard tone.
Bit 4 (GT55) = 0 (default) disables the 550 Hz Guard
tone. GT55 = 1 enables the 550 Hz Guard tone.
Bit 3 (CTE) = 0 (default) disables and CTE = 1 enables
the Calling Tone referred to in bit 14 (TOCT). The
Calling Tone is a 1300 Hz tone in originate mode with a
0.5–0.7 sec on/1.5–2.0 sec off cadence as described in
V.25.
going
off-hook
and
the
loop
AN93
Default
0x007A
0x0022
0x0258
0x6720
current
81