916.50 MHz
Transceiver Module
This pin is the receiver low-pass filter bandwidth adjust, and is connected directly to the transceiver LPFADJ pin. R6 on the
circuit board (12 K) is connected between LPFADJ and ground, and sets the receiver bandwidth for typical 115.2 kbps oper-
ation. The filter bandwidth can be increased by adding an external resistor in parallel with R6. The equivalent resistor value
can range from 12 K to 820 ohms, providing a filter 3 dB bandwidth f
LPF
from 120 kHz to 1.8 MHz. The 3 dB filter bandwidth
is determined by:
8
LPF ADJ
f
LPF
= 1445/(12*R
LPF
/(12 + R
LPF
)), where R
LPF
is in kilohms, and f
LPF
is in kHz
A ±5% resistor should be used to set the filter bandwidth. This will provide a 3 dB filter bandwidth between f
LPF
and 1.3* f
LPF
with variations in supply voltage, temperature, etc. The filter provides a three-pole, 0.05 degree equiripple phase response.
The peak drive current available from RXDATA increases in proportion to the filter bandwidth setting. Refer to sections 1.4.3,
2.5.1 and 2.6.1 in the ASH Transceiver Designer’s Guide for additional information on data rate adjustments.
9
10
VCC
GND
This is the positive supply voltage pin for the module. The operating voltage range is 2.7 to 3.5 Vdc. It is also possible to use
Pin 1 as the Vcc input. Please refer to the Pin 1 description above.
This is a ground pin.
CTR1 is connected to the CNTRL1 control pin on the transceiver. CTR1 and CTR0 select the transceiver operating modes.
CTR1 and CTR0 both high place the unit in the receive mode. CTR1 and CTR0 both low place the unit in the power-down
(sleep) mode. CTR1 high and CTR0 low place the unit in the ASK transmit mode. CTR1 low and CTR0 high place the unit in
the OOK transmit mode (not used at 115.2 kbps). CTR1 is a high-impedance input (CMOS compatible). This pin must be
held at a logic level; it cannot be left unconnected. At turn on, the voltage on this pin and CTR0 should rise with VCC until
VCC reaches 2.7 Vdc (receive mode). Thereafter, any mode can be selected.
CTR0 is connected to the CNTRL0 control pin on the transceiver CTR0 is used with CTR1 to control the operating modes of
the transceiver. CTR0 is a high-impedance input (CMOS compatible). This pin must be held at a logic level; it cannot be left
unconnected. At turn on, the voltage on this pin and CTR1 should rise with VCC until VCC reaches 2.7 Vdc (receive mode).
Thereafter, any mode can be selected.
RFIO is the RF input/output pin. A matching circuit for a 50 ohm load (antenna) is implemented on the circuit board between
this pin and the transceiver SAW filter transducer.
This pin is the RF ground (return) to be used in conjunction with the RFIO pin. For example, when connecting the transceiver
module to an external antenna, the coaxial cable ground is connected this pin and the coaxial cable center conductor is con-
nected to RFIO.
11
CTR1
12
CTR0
13
RFIO
14
RF GND
115.2 kbps Application Circuit
R/T
3 Vdc
12
13
11
10
9
8
7
DR3000-1
14
1
2
3
0.001 µF
2200 pF
4
5
3.3 K
Data In
Data Out
6
RF Monolithics, Inc.
Phone: (972) 233-2903
Fax: (972) 387-8148
RFM Europe
Phone: 44 1963 251383
Fax: 44 1963 251510
©1999 by RF Monolithics, Inc. The stylized RFM logo are registered trademarks of RF Monolithics, Inc.
E-mail: info@rfm.com
http://www.rfm.com
DR3000-1-060304
Page 4 of 5
RFM [ RF MONOLITHICS, INC ]
