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 +65°C or less. Aging may exceed the specification for prolonged temperatures
above +65°C. 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
= +25°C± 2°C
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 (+25°C)
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
µH
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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