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DNT2400 - 08/18/09
important that this connection be implemented as a 50 ohm stripline. Referring to Figure 3.3.1, the width
of this stripline depends on the thickness of the circuit board between the stripline and the groundplane.
For FR-4 type circuit board materials (dielectric constant of 4.7), the width of the stripline is equal to 1.75
times the thickness of the circuit board. Note that other circuit board traces should be spaced away from
the stripline to prevent signal coupling, as shown in Table 3.3.1. The stripline trace should be kept short to
minimize its insertion loss.
Trace Separation from
50 ohm Microstrip
Length of Trace Run
Parallel to Microstrip
100 mil
125 mill
150 mil
200 mil
200 mil
290 mil
250 mil
450 mil
300 mil
650 mil
Table 3.3.1
3.4 DNT2400 Antenna Connector
A U.FL miniature coaxial connector is provided on both DNT2400 configurations for connection to the
RFIO port. A short U.FL coaxial cable can be used to connect the RFIO port directly to an antenna. In this
case the antenna should be mounted firmly to avoid stressing the U.FL coaxial cable due to antenna
mounting flexure. Alternately, a U.FL coaxial jumper cable can be used to connect the DNT2400 module
to a U.FL connector on the host circuit board. The connection between the host circuit board U.FL con-
nector and the antenna or antenna connector on the host circuit board should be implemented as a 50
ohm stripline. Referring to Figure 3.3.1, the width of this stripline depends on the thickness of the circuit
board between the stripline and the groundplane. For FR-4 type circuit board materials (dielectric con-
stant of 4.7), the width of the stripline is equal to 1.75 times the thickness of the circuit board. Note that
other circuit board traces should be spaced away from the stripline to prevent signal coupling, as shown
in Table 3.3.1. The stripline trace should be kept short to minimize its insertion loss.
3.5 Input Voltages
DNT2400 radio modules can operated from an unregulated DC input (Pad 19) in the range of 3.3 (trough)
to 5.5 V (peak) with a maximum ripple of 5% over the temperature range of -40 to 85
o
C. Applying AC,
reverse DC, or a DC voltage outside the range given above can cause damage and/or create a fire and
safety hazard. Further, care must be taken so logic inputs applied to the radio stay within the voltage
range of 0 to 3.3 V. Signals applied to the analog inputs must be in the range of 0 to ADC_REF (Pad/Pin
3). Applying a voltage to a logic or analog input outside of its operating range can damage the DNT2400
module.
3.6 ESD and Transient Protection
The DNT2400C and DNT2400P circuit boards are electrostatic discharge (ESD) sensitive. ESD precau-
tions must be observed when handling and installing these components. Installations must be protected
from electrical transients on the power supply and I/O lines. This is especially important in outdoor instal-
lations, and/or where connections are made to sensors with long leads. Inadequate transient protection
can result in damage and/or create a fire and safety hazard.
