V.22bis Single Chip Modem
The 73M2901CL is designed to operate from a +3.6
to +2.7 volt supply with low power consumption
(~30mW @ 3.0 volts). The modem supports
automatic standby idle mode. The modem will also
accept a request to power down from the DTE via
hardware control. No additional major components
are required to complete the modem core logic. The
modem provides direct firmware LED support via
• Fully self-contained. “AT” Command interpreter
and data pump
• User pins available
• Synchronous serial data I/O available
• Asynchronous serial port
• On-chip hybrid and line driver.
• Autobaud capability from 300bps to 9600bps
Power is supplied to the 73M2901CL via the VPD
and VPA pins. The 73M2901CL is designed for a
single +3.6 to +2.7 volt supply and for low power
consumption (~30mW @ 3.0 volts). Ground is
supplied to the 73M2901CL via VND and VNA pins.
The 73M2901CL has been designed with separated
analog and digital supplies to insure the best
performance of the part by using different filtered
power supplies. It is recommended that separate
locally bypassed traces be used to apply power to
the analog supply VPA and the digital supply VPD.
LOW POWER MODE
The TDK 73M2901CL supports a low power standby
mode. If the low power standby option is enabled the
73M2901CL will go into a power saving mode when
idle. The oscillator will be running, clocks will be
supplied to the UART, timers and interrupt blocks;
but no clocks will be supplied to the CPU. Instruction
processing and activity on the internal busses is
halted. Normal operation is resumed when an
interruption such as assertion of '75 or 5,1*, a
character is sent to the 73M2901CL TXD input, or a
ANALOG LINE / HYBRID INTERFACE
The 73M2901CL provides a differential analog
output (TXAP and TXAN) and a single-ended analog
input (RXA) with internal A/D and D/A converters. A
driver is provided for an internal hybrid function.
The internal hybrid driver is capable of driving an
external load matching impedance and a line-
coupling transformer. The internal hybrid/line driver
senses the load and adapts itself to its requirements.
The 73M2901CL provides firmware control for a
hook relay driver (5(/$<) as well as interrupt
support for a ring detect opto-coupler (5,1*).
The external interrupt sources, '75 and 5,1*,
come from dedicated input pins of the same name.
DTR informs the 73M2901CL that the host has
requested the 73M2901CL perform a specific
function. The function of '75 can be changed by
“AT” commands (described in full in the TDK
73M2901CL User’s Guide).
RING is used to inform the 73M2901CL that the
external DAA circuitry has detected a ring signal.
In addition, sending any character on the TXD line
also generates an internal interrupt.
The TDK 73M2901CL single chip modem can use
an external 11.0592 MHz reference clock or can
generate a clock using only a crystal and two
capacitors. If an external clock is used, it should be
applied to OSCIN.