AMIS-30585 Datasheet, PDF (6/17 Pages) AMI SEMICONDUCTOR – S-FSK PLC Modem

AMIS−30585
Figure 5. Placement of the Capacitors and Crystal with Clock Signal Generated Internally
The crystal is a classical parallel resonance crystal of
24 MHz. The values of the capacitors CX are given by the
manufacturer of the crystal. Typical value is 30 pF. The
crystal has to fulfill impedance characteristics specified in
the AMIS−30585 data sheet. As an oscillator is sensitive and
precise, it is advised to put the crystal as close as possible on
the board.
Pin 14: 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).
Pin 15: VSS
VSS is the digital ground supply pin. This pin must be
decoupled from the digital supply by a 100 nF ±10 percent
ceramic capacitor. It is advised to put this capacitance as
close as possible on the PCB.
Pin 16: VDD
VDD is the 3.3 V digital supply pin. This pin must be
connected to VSS by a decoupling capacitor (C_DEC) as
explained for the pin 15.
Pin 17: TXD
TXD is the digital output of the asynchronous serial
communication (SCI) unit. Only half−duplex transmission
is supported. It is used to realize the communication between
the AMIS−30585 and the application microcontroller. The
TXD is an open drain IO (5 V safe). External pull−up
resistances (typically 10 K) are necessary to generate the 5 V
level. Refer to Figure 4 for the circuit schematic.
Pin 18: RXD
This is the digital input of the asynchronous SCI unit.
Only half−duplex transmission is supported. This pin
supports a 5 V level. It is used to realize the communication
between the AMIS−30585 and the application micro−
controller. The RXD is a 5 V safe input.
Pin 19: IO2
IO0, IO1 and IO2 are general−purpose digital input and
output pins. See Pin 6 for detailed explanation.
Pin 20, 21: BR1, BR0
BR0 and BR1 are digital input pins. They are used to select
the baud rate (bits/second) of the SCI unit. The rate is
defined according to Table 3. 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.
Table 3. BR1, BR0 BAUD RATES
BR1
BR0
SCI Baud Rate
0
0
4800
0
1
9600
1
0
19200
1
1
38400
Figure 6. Placement of Decoupling Capacitor
Pin 22: IO1
IO0, IO1 and IO2 are general−purpose digital input and
output pins. See Pin 6 for detailed explanation.
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