LMX9830SM National Semiconductor, LMX9830SM Datasheet - Page 39

• Manufacturer Part Number: LMX9830SM
• Manufacturer: National Semiconductor

Specifications of LMX9830SM

• Lead Free Status / Rohs Status: Not Compliant

15.0 Application Information
Figure 19 represents a typical system functional schematic
for the LMX9830 in its normal 3.0V or 3.3V system interface
operation.
In Figure 20 represents a typical system functional schematic
for the LMX9830 in its 1.8V system interface operation.
15.1 ANTENNA MATCHING NETWORK
The antenna matching network may or may not be required,
depending upon the impedance of the antenna chosen and
the trace impedance on the PCB. A 6.8 pF blocking capacitor
is recommended.
Note: Additional L network placement is recommended for tuning the trace
15.2 FILTERED POWER SUPPLY
It is important to provide the LMX9830 with adequate ground
planes and a filtered power supply. It is highly recommended
that a 0.1 µF and a 10 pF bypass capacitor be placed as close
as possible to V
operations.
Note: For 1.8V operations V
15.3 HOST INTERFACE
To set the logic thresholds of the LMX9830 to match the host
system, IOVCC (pin C4) must be connected to the logic power
impedance if needed.
tied directly to ground.
CC
(pin E1) on the LMX9830 for 2.5V and 3.3V
CC
filtering is not required and V
CC
should be
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supply of the host system. It is highly recommended that a 10
pF bypass capacitor be placed as close as possible to the
IOVCC pad on the LMX9830.
15.4 FREQUENCY AND BAUD RATE SELECTIONS
OP3, OP4, OP5 can be strapped to the host logic 0 and 1
levels to set the host interface boot-up configuration. Alterna-
tively all OP3, OP4, OP5 can be hardwired over 1kW pullup/
pulldown resistors. See Table 18.
15.5 START UP SEQUENCE OPTIONS
OP6, OP7, and Env1 can be left unconnected (both OP6 and
OP7 are pulled low and ENV1 is pulled high internally), These
can be hardwired over 1kW pullup/pulldown resistors. See
Table 17.
15.6 CLOCK INPUT
The clock source must be placed as close as possible to the
LMX9830. The quality of the radio performance is directly re-
lated to the quality of the clock source connected to the
oscillator port on the LMX9830. Careful attention must be paid
to the crystal/oscillator parameters or radio performance
could be drastically reduced.
15.7 SCHEMATIC AND LAYOUT EXAMPLES
See Figure 19, Figure 20, and full schematic in Section 16.0
Reference Design.
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