r6781-12 Conexant Systems, Inc., r6781-12 Datasheet - Page 41

• Manufacturer Part Number: r6781-12
• Description: Embedded Modem Family
• Manufacturer: Conexant Systems, Inc.

EmbeddedModem Family
Table 3-5. Hardware Interface Signal Definitions (1 of 5)
D224ATLVDSC
XTLI
XTLO
RESET
SEREN
VCC
VAA
DGND
AGND
IDLEN0
IDLEN1
SLEEP
SLEEPI
Label
IE
OE
IC
DI
PWR
GND
DI
DI
DO
DI
I/O Type
Crystal/Clock In and Crystal Out. The modem must be connected to an external crystal
circuit consisting of a 16.000312 MHz crystal and two capacitors. Alternatively, XTLI may be
driven with a buffered clock, in which case XTLO should be left open.
Reset. The active low RESET input resets the internal modem logic. Upon RESET
transitioning from high to low, modem operation returns to the state controlled by factory
default values and stored values in NVRAM. During modem power-on, RESET must be held
low for at least 5 ms after +5 VD and +5 VA operating voltage (see TSVD and +5 VA below) is
attained for the modem top stabilize.
to cause the modem to reset upon power turn on. When the parallel interface is selected,
RESET should be connected to the hose bus reset line.
Serial Interface Enable. When the SEREN input is low, serial interface is selected upon reset.
In this case, the serial interface signals should be connected to the V.24 (EIA-232-D) interface
and LED indicators.
Digital Supply. +5 V/3.3V ATLV ±5% is required.
Analog Supply. +5 V ±5% is required.
Digital and Analog Grounds.
Idle Enable 0 and Idle Enable 1. Encoded inputs enable or disable the sleep modes as
follows:
IDLEN1
If Idle option is enabled, the modem will enter idle mode after 5 seconds of inactivity
(WAKEUP must also be high for the serial interface). The modem will wakeup upon DTE
activity (RXD for parallel mode and low on WAKEUP for serial mode) or the presence of
RING.
inverted). The modem will enter stop mode after 5 seconds of inactivity (and if WAKEUP is
high for the serial interface). Only a 4 ms or longer pulse on the RING pin can wake up the
modem from stop mode.
Sleep Mode. SLEEP output high indicates the modem is operating in its normal mode.
SLEEP low indicates that the modem is in the sleep mode. The SLEEP output can also be
used to control power to other devices.
Sleep Mode. SLEEP input low causes the Integrated Analog (IA) to enter low-power sleep
mode.
When the serial interface is selected, RESET can be connected to an external RC network
L
L
H
H
If Stop option is selected, the RING input becomes RING (i.e., the RING signal must be
IDLEN0
L
H
L
H
Sleep Mode Signals
System Signals
Conexant
Idle mode disabled
Idle mode enabled
Stop mode disabled
Stop mode enabled
Signal Name/Description
Mode
3-15