RP1285
916.55 MHz SAW Resonator
RF Monolithics, Inc.
Phone: (972) 233-2903
Fax: (972) 387-9148
E-mail: info@rfm.com
Page 1 of 2
http://www.rfm.com
1998 by RF Monolithics, Inc. The stylized RFM logo are registered trademarks of RF Monolithics, Inc.
RP1285-120298
Ideal for 916.5 MHz FCC Part 15.249 Transmitters
Nominal Insertion Phase Shift of 180
at Resonance
Quartz Stability
Rugged, Hermetic, Low-Profile TO39 Case
The RP1285 is a two-port, 180
surface-acoustic-wave (SAW) resonator in a low-pro-
file TO39 case. It provides reliable, fundamental-mode, quartz frequency stabilization
of fixed-frequency transmitters operating at 916.5 MHz. The RP1285 is designed spe-
cifically for remote-control and data-link transmitters operating in the USA under FCC
Part 15.249 regulations and in Canada under DoC RSS-210.
CAUTION: Electrostatic Sensitive Device. Observe precautions for handling.
Notes:
1. Frequency aging is the change in f
C
with time and is specified at +65C or less. Aging may exceed the specification for prolonged temperatures
above +65C. Typically, aging is greatest the first year after manufacture, decreasing in subsequent years.
2. The frequency f
C
is the frequency of minimum IL with the resonator in the specified test fixture in a 50
test system with VSWR
1.2:1. Typically,
f
OSCILLATOR
or f
TRANSMITTER
is less than the resonator f
C
.
3. One or more of the following United States patents apply: 4,454,488; 4,616,197.
4. Typically, equipment utilizing this device requires emissions testing and government approval, which is the responsibility of the equipment manufac-
turer.
5. Unless noted otherwise, case temperature T
C
= +25C 2C
6. The design, manufacturing process, and specifications of this device are subject to change without notice.
7. Derived mathematically from one or more of the following directly measured parameters: f
C
, IL, 3 dB bandwidth, f
C
versus T
C
, and C
O
.
8. Turnover temperature, T
O
, is the temperature of maximum (or turnover) frequency, f
O
. The nominal frequency at any case temperature, T
C
, may be
calculated from: f = f
O
[1 - FTC (T
O
- T
C
)
2
]. Typically, oscillator T
O
is 20 less than the specified resonator T
O
.
9. This equivalent RLC model approximates resonator performance near the resonant frequency and is provided for reference only. The capacitance
C
O
is the measured static (nonmotional) capacitance between either pin 1 and ground or pin 2 and ground. The measurement includes case para-
sitic capacitance.
Electrical Characteristics
Characteristic
Sym
Notes
Minimum
Typical
Maximum
Units
Center Frequency (+25C)
Absolute Frequency
f
C
2, 3, 4, 5,
916.400
916.700
MHz
Tolerance from 916.550 MHz
f
C
150
kHz
Insertion Loss
IL
2, 5, 6
7.5
10.0
dB
Quality Factor
Unloaded Q
Q
U
5, 6, 7
6,500
50
Loaded Q
Q
L
3,800
Temperature Stability
Turnover Temperature
T
O
6, 7, 8
23
38
53
C
Turnover Frequency
f
O
f
C
+5.7
kHz
Frequency Temp. Coefficient
FTC
0.037
ppm/C
2
Frequency Aging
Absolute Value during First Year
|f
A
|
6
10
ppm/yr
DC Insulation Resistance between Any Two Pins
5
1.0
M
RF Equivalent RLC Model
Motional Resistance
R
M
5, 7, 9
137
217
Motional Inductance
L
M
155.005
H
Motional Capacitance
C
M
0.194528
fF
Shunt Static Capacitance
C
O
5, 6, 9
1.7
2.0
2.3
pF
Lid Symbolization (in addition to Lot and/or Date Codes)
RFM P1285
TO39-3 Case
916.55 MHz SAW Resonator
RF Monolithics, Inc.
Phone: (972) 233-2903
Fax: (972) 387-9148
E-mail: info@rfm.com
Page 2 of 2
http://www.rfm.com
1998 by RF Monolithics, Inc. The stylized RFM logo are registered trademarks of RF Monolithics, Inc.
RP1285-120298
Absolute Maximum Ratings
Rating
Value
Units
CW RF Power Dissipation (See: Typical Test Circuit)
+5
dBm
DC Voltage Between Any Two Pins (Observe ESD Precautions)
30
VDC
Case Temperature
-40 to +85
C
Electrical Connections
This two-port, three-terminal SAW resonator is bidirectional. However,
impedances and circuit board parasitics may not be symmetrical, requiring
slightly different oscillator component-matching values.
Typical Test Circuit
Typical Application Circuits
Case Design
Equivalent LC Model
Temperature Characteristics
Typical Frequency Response
Bottom View
Pin 1
Pin 2
Pin 3
Pin
Connection
1
Input or Output
2
Output or Input
3
Case Ground
50
Source at
F
C
Low-Loss
Matching
Network
50
to
Power Test
P
P
INCIDENT
INCIDENT
CW RF Power Dissipation =
-
REFLECTED
REFLECTED
P
P
1
3
2
2
3
1
From 50
Network
Analyzer
To 50
Network
Analyzer
Electrical Test
This SAW resonator can be used in oscillator or transmitter designs that
require 180 phase shift at resonance in a two-port configuration. One-
port resonators can be simulated, as shown, by connecting pins 1 and 2
together. However, for most low-cost consumer products, this is only
recommended for retrofit applications and not for new designs.
Phasing
& Match
Phasing
& Match
1
2
3
Conventional Two-Port Design: Simulated One-Port Design:
B
45
J
(2 places)
D
(3 places)
H
G
E
F
C
A
Dimensions
Millimeters
Inches
Min
Max
Min
Max
A
9.30
0.366
B
3.18
0.125
C
2.50
3.50
0.098
0.138
D
0.46 Nominal
0.018 Nominal
E
5.08 Nominal
0.200 Nominal
F
2.54 Nominal
0.100 Nominal
G
2.54 Nominal
0.100 Nominal
H
1.02
0.040
J
1.40
0.055
C
M
Co
Co
R
M
L
M
1
2
3
The following equivalent LC model is valid near resonance:
-80 -60 -40 -20
0 +20 +40 +60
0
-50
-100
-150
+80
-200
0
-50
-100
-150
-200
f
C
= f
O
, T
C
= T
O
T =
T
C
- T
O
( C )
(f-
f o
o
) /
f
(ppm
)
The curve shown on the right
accounts for resonator con-
tribution only and does not
include LC component tem-
perature contributions.
The plot shown below is a typical frequency response for
the RP series of two-port resonators. The plot is for RP1094.
-10.0
-20.0
-30.0
-40.0
-50.0
-60.0
200.0
100.0
0.0
-100.0
-200.0
-300.0
-400.0
-500.0
-600.0
-700.0
-800.0
901.2 905.2 909.2 913.2 917.2 921.2 925.2 929.2
Frequency (MHz)
S21 magn.(dB)
S21 phase (deg.)
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