Note that other circuit board traces should be spaced away from the stripline to prevent signal coupling, as shown in Table
6.3.2. The stripline trace should be kept short to minimize its insertion loss.
6.4
Power Supply and Input Voltages
DNT90M radio modules can operate from an unregulated DC input (Pad 19) in the range of 3.3 to 5.5 V with a maximum
ripple of 5% over the temperature range of -40 to 85 °C.
Applying AC, reverse DC, or a DC voltage outside the range giv-
en 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_EXT_REF (Pad/Pin 25). Applying a voltage to a logic or analog input outside of its operating range can damage the
DNT90M module.
6.5
ESD and Transient Protection
All DNT90M radio modules are electrostatic discharge (ESD) sensitive. ESD precautions must be observed when han-
dling 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 installations, 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.
6.6
Interfacing to 5 V Logic Systems
All logic signals including the serial ports on the DNT90M are 3.3 V signals. To interface to 5 V signals, the resistor divider
network shown in Figure 3.7.1 below must be placed between the 5 V signal outputs and the DNT90M signal inputs. The
output voltage swing of the DNT90M 3.3 V signals is sufficient to drive 5 V logic inputs.
Figure 6.6.1
6.7
Mounting and Enclosures
DNT90MC and DNT90MCA radio modules are mounted by reflow soldering them to a host circuit board. DNT90MP and
DNT90MPA modules are mounted by plugging their pins into a set of mating connectors on the host circuit board. Refer to
Section 10.3 for connector details.
DNT90M radio enclosures must be made of plastics or other materials with low RF attenuation to avoid compromising
antenna performance where antennas are internal to the enclosure. Metal enclosures are not suitable for use with internal
antennas as they will block antenna radiation and reception. Outdoor enclosures must be water tight, such as a NEMA 4X
enclosure.
DNT90
©2012 by Murata Electronics N.A., Inc.
DNT90M Integration Guide (2012/09/17)
Page 26 of 74
www.murata.com
