868.35 MHz
Receiver Module
This pin is the receiver low-pass filter bandwidth adjust, and is connected directly to the receiver LPFADJ pin. R6 on the cir-
cuit board (330 K) is connected between LPFADJ and ground will be in parallel with any external resistor connected to LPF
ADJ. The filter bandwidth is set by the parallel resistance of R6 and the external resistor (if used). The equivalent resistor
value can range from 330 K to 820 ohms, providing a filter 3 dB bandwidth f
from 4.4 kHz to 1.8 MHz. The 3 dB filter
LPF
bandwidth is determined by:
f
= 1445/ (330*R /(330 + R )), where R
is in kilohms, and f
is in kHz
LPF
LPF
LPF
LPF
LPF
8
LPF ADJ
A ±5% resistor should be used to set the filter bandwidth. This will provide a 3 dB filter bandwidth between f
and 1.3* f
LPF
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. As shipped, the
receiver module is set up for nominal 2.4 kbps operation. An external resistor can be added between Pin 8 and ground to
support higher data rates. Preamble training times will not be decreased, however, unless C3 is replaced with a smaller
capacitor value (see the descriptions of Pins 2 and 3 above). 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.
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.
9
VCC
GND
10
This is the supply voltage return pin.
CTR1 is connected to the CNTRL1 control pin on the receiver. 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 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.
11
12
CTR1
CTR0
CTR0 is connected to the CNTRL0 control pin on the receiver CTR0 is used with CTR1 to control the operating modes of the
receiver. CTR0 is a high-impedance input (CMOS compatible). This pin must be held at a logic level; it cannot be left uncon-
nected. At turn on, the voltage on this pin and CTR1 should rise with VCC until VCC reaches 2.7 Vdc (receive mode). There-
after, 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 receiver SAW filter transducer.
13
14
RFIO
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.
RF GND
2.4 kbps Application Circuit
19.2 kbps Application Circuit
3 Vdc
3 Vdc
12
13
14
11
10
9
4
8
5
12
13
14
9
4
8
5
11
10
7
6
33 k
7
6
DR5001
DR5001
DR3000
1
2
3
1
2
3
Data Out
Data Out
RF Monolithics, Inc.
RFM Europe
Phone: (972) 233-2903
Phone: 44 1963 251383
Fax: (972) 387-8148
Fax: 44 1963 251510
E-mail: info@rfm.com
http://www.rfm.com
DR5001-081203
Page 3 of 4
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RFM [ RF MONOLITHICS, INC ]
