www.RFM.com E-mail: info@rfm.com Page1of7
©2008-2009 by RF Monolithics, Inc. DNT900 - 06/11/09
DNT900
Rating Value Units
All Input/Output Pins -0.5 to +3.3 V
Non-Operating Ambient Temperature Range -40 to +85 oC
DNT900 Absolute Maximum Ratings
DNT900 Electrical Characteristics
Characteristic Sym Notes Minimum Typical Maximum Units
Operating Frequency Range 902.75 927.25 MHz
Hop Dwell Time 5 200 ms
Number of RF Channels 50
Modulation FSK
RF Data Transmission Rates 1 38.4, 115.2, 200 and 500 kb/s
Receiver Sensitivity:
10-5 BER @ 38.4 kb/s -108 dBm
10-5 BER @ 200 kb/s -98 dBm
10-5 BER @ 500 kb/s -94 dBm
Transmitter RF Output Power Levels 1 1, 10, 100, 250, 500, 1000 at 38.4 to 200 kb/s
1, 10, 85 at 500 kb/s mW
Optimum Antenna Impedance 50 W
RF Connection DNT900P - U.FL Coaxial Connector
DNT900C - U.FL Connector or PCB Pad
Network Topologies Point-to-Point, Point-to-Multipoint
Access Schemes CSMA and TDMA
Low Cost
900 MHz FHSS
Transceiver
Module with
I/O
The DNT900 FHSS transceiver module is a low cost, high-power solution for point-to-
point and point-to-multipoint wireless systems in the 900 MHz ISM band. The RF output
power of the DNT900 can be set from 1 mW to 1 W, and the RF data rate can be set
from 38.4 to 500 kb/s. The DNT900 receiver includes a low-noise preamplifier protected
by two SAW filters, providing an excellent combination of receiver sensitivity and out-of-
band interference rejection. The DNT900 module includes analog, digital and serial I/O,
providing the flexibility and versatility to serve applications ranging from cable replace-
ments to sensor networks. The DNT900 transceiver module is easy to integrate and pro-
vides robust wireless communications up to 40 miles in line-of-sight installations.
Shown with Shield Removed
DEVELOPMENT KIT
(Info Click here)
·900 MHz Frequency Hopping Spread Spectrum Transceiver
·Point-to-Point and Point-to-Multipoint Network Topologies
·Transmitter Power Configurable from 1 mW to 1 W
·RF Data Rate Configurable from 38.4 to 500 kb/s
·Serial Port Rate up to 460.8 kb/s for Streaming Applications
·128-Bit AES Encryption
·Separate Serial Port for Diagnostics
·Analog and Digital I/O for Sensor Applications
·FCC and Canadian IC Certified for Unlicensed Operation
Notes:
1. The DNT900 achieves regulatory certification under FHSS rules at air data rates of 38.4, 115.2 and 200 kb/s. At 500 kb/s,
the DNT900 achieves regulatory certification under “digital modulation” or DTS rules. The DNT900 still employs frequency
hopping at 500 kb/s to mitigate the effects of interference and multipath fading, but hops on fewer, more widely spaced
frequencies than at lower data rates. Maximum RF power at 500 kb/s is 85 mW.
2. PWM is set with an 8-bit value. DAC resolution is limited to 7 bits by residual ripple at output of low-pass filter.
3. Maximum sleep current occurs at +85 oC.
www.RFM.com E-mail: info@rfm.com Page2of7
©2008-2009 by RF Monolithics, Inc. DNT900 - 06/11/09
Characteristic Sym Notes Minimum Typical Maximum Units
Number of Network Nodes:
TDMA Mode 16
CSMA Mode unlimited
ADC Input Range 0 3.3 V
ADC Input Resolution 10 bits
ADC Sample Rate 10 ms
Signal Source Impedance for ADC Reading 10 KW
PWM (DAC) Output Range 0 3.3 V
PWM (DAC) Output Resolution 2 8 bits
PWM Output Period 20 µs
Primary Serial Port Baud Rates 1.2, 2.4, 4.8, 9.6, 19.2, 28.8, 38.4, 57.6, 76.8,
115.2, 230.4, 460.8 kb/s
Diagnostic Serial Port Baud Rate 38.4 kb/s
Digital I/O:
Logic Low Input Level -0.5 0.8 V
Logic High Input Level 2 3.3 V
Logic Input Internal Pull-up Resistor 50 200 KW
Logic Input Internal Pull-down Resistor 50 180 KW
Power Supply Voltage Range VCC +3.3 +5.5 Vdc
Power Supply Voltage Ripple 10 mVP-P
Peak Transmit Mode Current, 1 W Output 1200 mA
Average Operating Receive Current:
Base 105 mA
Remote, No Data Transmission 35 mA
Remote, 9.6 kb/s Continuous Data Stream 40 mA
Remote, 115.2 kb/s Continuous Data Stream 53 mA
Sleep Current 3 50 225 µA
DNT900C Mounting Reflow Soldering
DNT900P Mounting Socket
Operating Temperature Range -40 85 oC
Operating Relative Humidity Range, Non-condensing 10 90 %
DNT900 Electrical Characteristics
CAUTION: Electrostatic Sensitive Device. Observe precautions when handling.
DNT900 Hardware
The major components of the DNT900 include a 900 MHz
FHSS transceiver and a low current 32-bit microcontroller.
The DNT900 operates in the 902 to 928 MHz ISM band.
There are a number of selectable hopping patterns includ-
ing patterns compatible with frequency allocations in the
US, Canada, South America, Israel, Australia and New
Zealand. The DNT900 has six selectable RF output power
levels: 1, 10, 100, 250 and 500 mW plus 1 W. Also, there
are four selectable RF transmission rates: 38.4, 115.2,
200 and 500 kb/s.
The DNT900 includes a low-noise preamplifier protected
by two SAW filters, providing an excellent blend of receiver
sensitivity and out-of-band interference rejection that is
especially important in outdoor applications.
The DNT900 provides a variety of hardware interfaces.
There are two UART serial ports, one for data and a sec-
ond for diagnostics. The data port supports standard baud
rates from 1.2 to 460.8 kb/s and the diagnostic port is fixed
at 38.4 kb/s. Also included are three 10-bit ADC inputs,
two 8-bit PWM outputs, and six general-purpose digital I/O
ports. Four of the digital I/O ports support an optional inter-
rupt-from-sleep mode when configured as inputs. The
radio is available in two mounting configurations. The
DNT900C is designed for solder reflow mounting. The
DNT900P is designed for plug-in connector mounting.
DNT900 Firmware
The DNT900 firmware can operate using either TDMA or
CSMA channel access modes. TDMA supports up to 16
remotes with rapid, deterministic channel latency. CSMA
provides carrier-sense managed channel access for an
unlimited number of low-traffic remotes. DNT900 firmware
will operate “out of the box” using its point-to-point trans-
parent serial mode, with point-to-multipoint supported by
the firmware’s protocol mode. DNT900 firmware provides
the user with a rich set of configuration options including a
choice of hopping patterns, hopping dwell times, RF data
transmission rates, serial port data rates and RF power
levels, plus configurable analog and digital I/O lines. Data
integrity is protected by 24-bit error detection, with optional
ACK and automatic transmission retries or redundant
transmissions. 128-bit AES encryption provides a high
level of data security for sensitive applications. Sensor net-
works can take advantage of timer or event-based data
reporting and remote node sleep cycling for extended
battery life.
www.RFM.com E-mail: info@rfm.com Page3of7
©2008-2009 by RF Monolithics, Inc. DNT900 - 06/11/09
2 3 2 4 2 5 2 6 2 7 2 82 22 1 2 9 3 0 3 1
1 8
1 7
1 6
1 5
1 4
1 3
1 2
1 1
1 0
9
8
7
6
5
D N T 9 0 0 B l o c k D i a g r a m
3 2 3 3 3 4 3 6
M i c r o c o n t r o l l e r
4
3
2
1
R e g
F i l t e r
F i l t e r
V C C
P W M 0
P W M 1
G P I O 0
G P I O 1
G P I O 2
G P I O 3
G N D
4 2
R F
T r a n s c e i v e r
C L K
I N T
C S n R F I O
G N D
R A D I O _ T X D
R A D I O _ R X D
/ R E S E T
R S V D
R S V D
R S V D
T / R
T / R
P W R
P R E
F i l t e r
3 5
4 1
4 3
1 9
2 0
3 7 3 8 3 9 4 0
S I
S O
P K T D E T
R e g
3 . 3 V
3 . 6 V
P K T _ D E T
R S V D
A D C _ R E F
R S S I
S L E E P
A D C 2
A D C 1
A D C 0
R S V D
D I A G _ T X
D I A G _ R X
/ C F G
/ H O S T _ R T S
/ H O S T _ C T S
G P I O 4
G P I O 5
G N D
A C T
/ D C D
R S V D
R S V D
R S V D
V M O D
R S V D
R S V D
Figure 1
Pin Name I/O Description
1 PKT_DET O
Packet detect output. Signal switches logic high at the end of the start-of-packet symbol and switches logic
low at the end of the end-of-packet symbol on both received and transmitted packets. PKT_DET provides a
timing reference for external use in network timing evaluations, etc.
2 RSVD - Reserved pin. Leave unconnected.
3 ADC_REF I ADC supply and external full scale reference voltage input. Voltage range is 2.4 to 3.3 Vdc. Connect pad 34 to
this input to reference the ADC full scale reading to the module’s 3.3 V regulated supply.
4 RSVD - Reserved pin. Leave unconnected.
5 GPIO0 I/O
Configurable digital I/O port 0. When configured as an input, an internal pull-up resistor can be selected and
interrupt from sleep can be invoked. When configured as an output, the power-on state is configurable. The
sleep mode direction and state are also configurable.
6 GPIO1 I/O Configurable digital I/O port 1. Same configuration options as GPIO0.
7 GPIO2 I/O Configurable digital I/O port 2. Same configuration options as GPIO0.
8 GPIO3 I/O Configurable digital I/O port 3. Same configuration options as GPIO0.
9 PWM0 O 8-bit pulse-width modulated output 0 with internal low-pass filter. Filter is first-order, with a159 Hz 3 dB
bandwidth.
10 PWM1 O 8-bit pulse-width modulated output 1 with internal low-pass filter. Filter is first-order, with a 159 Hz 3 dB
bandwidth.
11 SLEEP/DTR I Active high module sleep input (active low DTR). When switched low after sleep, the module executes a
power on-reset. Usually connected to host DTR. Connect to ground if SLEEP/DTR function not used.
12 ADC2 I 10-bit ADC input 0. Full scale reading is referenced to the ADC_REF input.
13 ADC1 I 10-bit ADC input 1. Full scale reading is referenced to the ADC_REF input.
14 ADC0 I 10-bit ADC input 2. Full scale reading is referenced to the ADC_REF input.
15 RSVD - Reserved pad. Leave unconnected.
16 DIAG_TX O Diagnostic UART transmitter output.
17 DIAG_RX I Diagnostic UART receiver input.
18 /CFG I Protocol selection input. Leave unconnected when using software commands to select transparent/protocol
mode (default is transparent mode). Logic low selects protocol mode, logic high selects transparent mode.
19 VCC I Power supply input, +3.3 to +5.5 Vdc.
20 GND - Power supply and signal ground. Connect to the host circuit board ground.
21 GND - Power supply and signal ground. Connect to the host circuit board ground.
22 GPIO4 I/O Configurable digital I/O port 4. When configured as an input, an internal pull-up resistor can be selected.
When configured as an output, the power-on state is configurable.
23 GPIO5 I/O Configurable digital I/O port 5. Same configuration options as GPIO4.
24 GND - Logic ground.
25 ACT O Data activity output, logic high when data is being transmitted or received.
26 /DCD O
Default functionality is data carrier detect output, logic low on a remote when the module is locked to FHSS
hopping pattern and logic low on a base station when at least one remote is connected to it. The sleep mode
state of this pin and /HOST_CTS is jointly configurable.
27 RSVD - Reserved pin. Leave unconnected.
28 RSVD - Reserved pin. Leave unconnected.
29 RSVD - Reserved pin. Leave unconnected.
www.RFM.com E-mail: info@rfm.com Page4of7
©2008-2009 by RF Monolithics, Inc. DNT900 - 06/11/09
DNT900 I/O Descriptions
Pin Name I/O Description
30 /HOST_RTS I UART flow control input. The host sets this line low to allow data to flow from the DNT900 on the RADIO_TXD
pin. When the host sets this line high, the DNT900 will stop sending data to the host.
31 RADIO_TXD O UART transmitter output. The DNT900 sends serial data to the host on this pin. The sleep mode state of this
pin is configurable.
32 RADIO_RXD I UART receiver input. The DNT900 receives serial data from the host on this pin.
33 /HOST_CTS O
UART flow control output. The DNT900 sets this line low to indicate it is ready to accept data from the host on
the RADIO_RXD input. When the DNT900 sets this line high, the host must stop sending data. The sleep
mode state of this pin and /DCD is jointly configurable.
34 VMOD O Module’s +3.3 V regulated supply. Connect to pad 3 to support 3.3 V full scale and/or ratiometric ADC read-
ings, etc. Current drain on this output should be no greater than 5 mA.
35 RSVD - Reserved pin. Leave unconnected.
36 RSVD - Reserved pin. Leave unconnected.
37 RSVD - Reserved pin. Leave unconnected.
38 RSVD - Reserved pin. Leave unconnected.
39 /RESET I Active low module hardware reset.
40 RSVD - Reserved pin. Leave unconnected.
41 GND - RF ground for the DNT900C only. Connect to the host circuit board ground plane.
42 RFIO I/O Alternate RF port for the DNT900C only. The antenna can be connected to this port with a 50 ohm stripline or
coaxial cable. Leave unconnected when using the U.FL connector.
43 GND - RF ground for the DNT900C only. Connect to the host circuit board ground plane.
www.RFM.com E-mail: info@rfm.com Page5of7
©2008-2009 by RF Monolithics, Inc. DNT900 - 06/11/09
D N T 9 0 0 C O u t l i n e a n d M o u n t i n g D i m e n s i o n s
D i m e n s i o n s i n i n c h e s
2 . 0 1 0
1 . 2 6 0
0 . 5 9 5
0 . 1 8 0
0 . 0 4 0 0 . 0 4 0 0 . 1 0 0
1
4 0
Figure 2
DNT900C RFIO Stripline
The DNT900C has a U.FL coaxial connector mounted near pad 42 for antenna connection (see Antenna Connec-
tor discussion below). It is also possible to connect an antenna using a stripline from pad 42. It is important that
this connection be implemented as a 50 ohm stripline. Referring to Figure 3, 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
www.RFM.com E-mail: info@rfm.com Page6of7
©2008-2009 by RF Monolithics, Inc. DNT900 - 06/11/09
C o p p e r
G r o u n d
P l a n e
C o p p e r
S t r i p l i n e
T r a c e
F R - 4 P C B
M a t e r i a l
C i r c u i t B o a r d S t r i p l i n e T r a c e D e t a i l
F o r 5 0 o h m i m p e d a n c e W = 1 . 7 5 * H
Figure 3 Figure 4
Trace Separation from
50 ohm Microstrip
Length of Trace Run
Parallel to Microstrip
100 mil 125 mil
150 mil 200 mil
200 mil 290 mil
250 mil 450 mil
300 mil 650 mil
D N T 9 0 0 P O u t l i n e a n d M o u n t i n g D i m e n s i o n s
D i m e n s i o n s i n i n c h e s
2 . 0 5 0
0 . 2 8 5
0 . 0 4 0 0 . 1 0 0
0 . 3 3 3
0 . 0 5 0
1 . 3 6 0
1
4 0
Figure 5
that other circuit board traces should be spaced away from the stripline to prevent signal coupling, as shown in
Figure 4. The stripline trace should be kept short to minimize its insertion loss.
DNT900 Antenna Connector
A U.FL miniature coaxial connector is provided on both DNT900 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 DNT900 module to a U.FL connector on the host circuit
board. The connection between the host circuit board U.FL connector and the antenna or antenna connector on
the host circuit board should be implemented as a 50 ohm stripline. Referring to Figure 3, 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 cir-
cuit board. Note that other circuit board traces should be spaced away from the stripline to prevent signal cou-
pling, as shown in Figure 4. The stripline trace should be kept short to minimize its insertion loss.
www.RFM.com E-mail: info@rfm.com Page7of7
©2008-2009 by RF Monolithics, Inc. DNT900 - 06/11/09
1 . 9
( 4 8 . 3 )
2 . 0
( 5 0 . 8 )
0 . 1
( 2 . 5 )
D N T 9 0 0 P I n t e r f a c e C o n n e c t o r
P C B L a y o u t D e t a i l
0 . 1
( 2 . 5 )
C o n n e c t o r s a r e F C I E l e c t r o n i c s 7 5 9 1 5 - 4 2 0 L F o r e q u i v a l e n t
D i m e n s i o n s i n i n c h e s a n d ( m m )
1 . 2 6
M i n i m u m p l a t e d P C B
h o l e d i a m e t e r 0 . 0 3 ( 0 . 7 5 )
Figure 6
Note: Specifications subject to change without notice.
Part # M-0900-0000, Rev B
