AD28msp01KST AD [Analog Devices], AD28msp01KST Datasheet - Page 14

• Manufacturer Part Number: AD28msp01KST
• Description: PSTN Signal Port
• Manufacturer: AD [Analog Devices]

Asynchronous Fallback Mode
The Asynchronous Fallback Mode is shown in Figure 11.
TCONV, TBIT and TBAUD are generated internally and can
be phase adjusted with the Transmit Phase Adjust Register
(Control Register 5). RCONV, RBIT and RBAUD are gener-
ated internally and can also be phase adjusted with the Receive
Phase Adjust Register (Control Register 4). The digital phase-
locked is not used in this operating mode.
AD28msp01
Asynchronous Fallback TSYNC Mode
The Asynchronous Fallback TSYNC Mode is shown in Figure
10. TCONV, TBIT and TBAUD are generated internally but
phase locked to the external TSYNC input signal. RCONV,
RBIT and RBAUD are generated internally and can be phase
adjusted with the Receive Phase Adjust Register (Control
Register 4).
This mode is entered by setting the Operating Mode field in
Control Register 0. The RCONV/TCONV rate can be set to
ANALOG OUT
ANALOG IN
MCLK
TSYNC
Figure 10. Asynchronous Fallback TSYNC Driven Mode Block Diagram
D/A
A/D
DIGITAL PHASE
LOCKED LOOP
PHASE ADJUST
PHASE ADJUST
TX CLOCKS
RX CLOCKS
TX CLOCKS
16
16
RCONV
RBAUD
TCONV
TBAUD
RBIT
TBIT
REGISTER 0
REGISTER 2
DATA
DATA
CONVERT
START
AD28msp01
–14–
RX PHASE ADJUST
REGISTER 4
This mode is entered by setting the Operating Mode field in
Control Register 0. The RCONV/TCONV rate can be set to
9.6 kHz, 8.0 kHz or 7.2 kHz by setting the sample rate bit field
in Control Register 0. The TBIT and TBAUD clock rates are
set by adjusting the appropriate bits in Control Register 3. The
RBIT and RBAUD clock rates are set by adjusting the appropri-
ate bits in Control Register 2. The bit and baud rates can be set
to any combination of clock rates listed in the control register
descriptions.
9.6 kHz, 8.0 kHz or 7.2 kHz by setting the sample rate bit field
in Control Register 0. The TBIT and TBAUD clock rates are
set by adjusting the appropriate bits in Control Register 3. The
RBIT and RBAUD clock rates are set by adjusting the appropri-
ate bits in Control Register 2. The bit rates, baud rates and
TSYNC rate can be set to any combination of clock rates listed
in the control register descriptions.
CONTROL
16
16
DSP Processor
FROM MODEM TX
TO MODEM RX
REV. A