NCN49599 Datasheet, PDF (8/39 Pages) ON Semiconductor – Power Line Carrier Modem

NCN49599
configuration RX_DATA outputs a pulse train with a 10 Hz
frequency. After Synchronization Confirm Time out
RX_DATA = 0. If NCN49599 is searching for
synchronization RX_DATA = 1.
+5V
R
Output
VSSD
PC20090722. 2
Figure 4. Representation of 5V Safe Output
TDO, TDI, TCK, TMS, and TRSTB
All these pins are part of the JTAG bus interface. The
JTAG interface is used during production test of the IC and
will not be described here. Input pins (TDI, TCK, TMS, and
TRSTB) contain internal pull−down resistance. TDO is an
output. When not used, the JTAG interface pins may be left
floating.
TXD/PRES
TXD/PRES is the output for either the transmitting data
(TX_DATA) or a synchronization signal with the time−slots
(PRE_SLOT). TXD/PRES. More information can be found
in paragraph Local Port.
XIN
XIN is the analog input pin of the oscillator. It is connected
to the interval oscillator inverter gain stage. The clock signal
can be created either internally with the external crystal and
two capacitors or by connecting an external clock signal to
XIN. For the internal generation case, the two external
capacitors and crystal are placed as shown in Figure 5. For
the external clock connection, the signal is connected to XIN
and XOUT is left unused.
XTAL_IN
XTAL_OUT
EXT_CLK_E
PC20120530.2
48 MHz
C_X
C_X
V_SSA
Figure 5. Placement of the Capacitors and Crystal
with Clock Signal Generated Internally
The crystal is a classical parallel resonance type with its
fundamental frequency equal to 48 MHz. For a typical load
capacitance C_L = 18 pF specified by the manufacturer of the
crystal, the value of C_X = 36 pF. The crystal has to fulfill
impedance characteristics specified in the NCN49599 data
sheet. As an oscillator is sensitive and precise, it is advised
to put the crystal as close as possible on the board and to
ground the case.
XOUT
XOUT is the analog output pin of the oscillator. When the
clock signal is provided from an external generator, this
output must be floating. When working with a crystal, this
pin cannot be used directly as clock output because no
additional loading is allowed on the pin (limited voltage
swing).
EXT_CLK_E
EXT_CLK_E allows the user to connect an external clock
instead of using a quartz. When this pin pulled to VDD an
external clock has to be applied to the XIN pin. When
EXT_CLK_E is connected to VSS, the quartz oscillator is
operational.
TXD
TXD is the digital output of the asynchronous serial
communication (SCI) unit. In half−duplex transmission
(when booting from ROM) and in full−duplex mode (booted
from Flash or after download over UART) it is used to
realize the communication between the NCN49599 and the
application microcontroller. The TXD is an open drain IO
(5 V safe). External pull−up resistances (typically 10 kW)
are necessary to generate the 5 V level. See Figure 4 for the
circuit schematic.
RXD
This is the digital input of the asynchronous SCI unit. It is
used in both half−duplex and full−duplex transmission (see
TXD pin description). This pin supports a 5 V level. It is used
to realize the communication between the NCN49599 and
the application microcontroller. RXD is a 5 V safe input.
T_REQ (in ROM Mode Only)
T_REQ is the transmission request input of the Serial
Communication Interface when used in half−duplex mode.
When pulled low its initiate a local communication from the
application micro controller to NCN49599. T_REQ is a 5 V
safe input. See also paragraph Serial Communication
Interface.
BR1, BR0
BR0 and BR1 are digital input pins. They are used to select
the baud rate (bits/second) of the Serial Communication
Interface unit in half−duplex mode. The rate is defined
according to Table 29 BR1, BR0 Baud Rate. The values are
taken into account after a reset, hardware or software.
Modification of the baud rate during function is not possible.
BR0 and BR1 are 5 V safe.
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