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Preliminary
Product Description
Ordering Information
Typical Applications
Features
Functional Block Diagram
RF Micro Devices, Inc.
7625 Thorndike Road
Greensboro, NC 27409, USA
Tel (336) 664 1233
Fax (336) 664 0454
http://www.rfmd.com
Optimum Technology Matching Applied
Si BJT
GaAs MESFET
GaAs HBT
Si Bi-CMOS
SiGe HBT
Si CMOS
Prescaler
32/64
Phase
Detector &
Charge Pump
Lock
Detect
LO
OP
F
L
T
14
16
DIV
C
T
R
L
DC
Bias
5
TX OUT
2
OS
C
E
1
OS
C
B
15
LD
F
L
T
MO
D
I
N
8
R
ESN
TR
+
13
R
ESN
TR
-
12
3
PD
RF2516
VHF/UHF TRANSMITTER
315/433MHz Band Systems
Local Oscillator Source
Part 15.231 Applications
Remote Keyless Entry
Wireless Security Systems
AM/ASK/OOK Transmitter
The RF2516 is a monolithic integrated circuit intended for
use as a low-cost AM/ASK transmitter. The device is pro-
vided in a 16-pin QSOP-16 package and is designed to
provide a phased locked frequency source for use in local
oscillator or transmitter applications. The chip can be
used in applications in the North American and European
VHF/UHF bands. The integrated VCO, phase detector,
prescaler, and reference oscillator transistor require only
the addition of an external crystal to provide a complete
phase-locked loop. In addition to the standard power-
down mode, the chip also includes an automatic lock-
detect feature that disables the transmitter output when
the PLL is out-of-lock.
Fully Integrated PLL Circuit
Integrated VCO and Reference Oscillator
2.0V to 3.6V Supply Voltage
Low Current and Power Down Capability
100MHz to 500MHz Frequency Range
Out-of-Lock Inhibit Circuit
RF2516
VHF/UHF Transmitter
RF2516 PCBA
Fully Assembled Evaluation Board
11
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0.157
0.150
0.196
0.189
0.2440
0.2284
0.0688
0.0532
0.050
0.016
0.0098
0.0075
8 MAX
0MIN
NOTES:
1. Shaded lead is Pin 1.
2. All dimensions are excluding mold flash.
3. Lead coplanarity - 0.005 with respect to datum "A".
0.012
0.008
0.025
-A-
0.0098
0.0040
Package Style: QSOP-16
Preliminary
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Absolute Maximum Ratings
Parameter
Rating
Unit
Supply Voltage
-0.5 to +3.6
V
DC
Power Down Voltage (V
PD
)
-0.5 to V
CC
V
MOD IN
-0.5 to 1.1
V
Operating Ambient Temperature
-40 to +85
C
Storage Temperature
-40 to +150
C
Parameter
Specification
Unit
Condition
Min.
Typ.
Max.
Overall
T = 25C, V
CC
= 2.8V, Freq=433MHz,
R
MODIN
=3k
Frequency Range
100 to 500
MHz
Modulation
AM/ASK
Modulation Frequency
1
MHz
Incidental FM
15
kHz p-p
Output Power
+8.5
+10
dBm
50
load
ON/OFF Ratio
75
dB
PLL and Prescaler
Prescaler Divide Ratio
32/64
VCO Gain, K
VCO
20
MHz/V
Frequency and board layout dependent.
PLL Phase Noise
-97
dBc/Hz
10kHz Offset, 50kHz loop bandwidth
-102
dBc/Hz
100kHz Offset, 50kHz loop bandwidth
Harmonics
-60
dBc
With output tuning.
Reference Frequency
17
MHz
Crystal Frequency Spurs
-50
dBc
50kHz PLL loop bandwidth
Max Crystal R
S
TBD
35
50
For a typ. 1ms turn-on time.
Max Crystal Motional Inductance
60
mH
For a typ. 1ms turn-on time.
Charge Pump Current
100
A
K
PD
= 100
A/2
= 0.0159mA/rad
Power Down Control
Power Down "ON"
V
CC
-0.3V
V
Voltage supplied to the input; device is "ON"
Power Down "OFF"
+0.3
V
Voltage supplied to the input; device is "OFF"
Control Input Impedance
100k
Turn On Time
1
2
ms
Crystal start-up, 13.57734MHz crystal.
Turn Off Time
1
2
ms
Power Supply
Voltage
2.8
V
Specifications
2.0
3.6
V
Operating limits
Current Consumption (Avg.)
6
10.5
mA
50% Duty Cycle 10kHz Data applied to the
MOD IN input. R
MODIN
(R10) = 3k
. Output
power/DC current consumption externally
adjustable by modulation input resistor (see
applicable Application Schematic).
Power Down Current
0
1
uA
PD=0V, MOD IN= 0V, DIV CTRL=0V
Caution! ESD sensitive device.
RF Micro Devices believes the furnished information is correct and accurate
at the time of this printing. However, RF Micro Devices reserves the right to
make changes to its products without notice. RF Micro Devices does not
assume responsibility for the use of the described product(s).
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Pin
Function
Description
Interface Schematic
1
OSC B
This pin is connected directly to the reference oscillator transistor base.
The intended reference oscillator configuration is a modified Colpitts. A
68pF capacitor should be connected between pin 1 and pin 2. Diodes
shown in the interface schematic provide 3kV electrostatic discharge
(ESD) protection using the human body model.
2
OSC E
This pin is connected directly to the emitter of the reference oscillator
transistor. A 33pF capacitor should be connected from this pin to
ground. Diodes shown in the interface schematic provide 3kV electro-
static discharge (ESD) protection using the human body model.
See pin 1.
3
PD
Power Down control for all circuitry. When this pin is a logic "low" all cir-
cuits are turned off. When this pin is a logic "high", all circuits are oper-
ating normally. A "high" is V
CC
. Diodes shown in the interface
schematic provide 3kV electrostatic discharge (ESD) protection using
the human body model.
4
GND
Ground connection for the TX OUT amp. Keep traces physically short
and connect immediately to ground plane for best performance. Diodes
shown in the interface schematic provide 3kV electrostatic discharge
(ESD) protection using the human body model.
5
TXOUT
Transmitter output. This output is an open collector and requires a pull-
up inductor for bias/matching and a tapped capacitor for matching.
6
GND1
Ground connection for the TX output buffer amplifier. Diodes shown in
the interface schematic provide 3kV electrostatic discharge (ESD) pro-
tection using the human body model.
See pin 4.
7
VCC1
This pin is used to supply bias to the TX buffer amplifier. Diodes shown
in the interface schematic provide 3kV electrostatic discharge (ESD)
protection using the human body model.
8
MOD IN
AM analog or digital modulation can be imparted to the carrier by an
input to this pin. An external resistor is used to bias the output amplifi-
ers through this pin. The voltage at this pin must not exceed 1.1V.
Higher voltages may damage the device. Diodes shown in the interface
schematic provide 3kV electrostatic discharge (ESD) protection using
the human body model.
9
VCC2
This pin is used to supply DC bias to the VCO, crystal oscillator, pre-
scaler, phase detector, and charge pump. An IF bypass capacitor
should be connected directly to this pin and returned to ground. Diodes
shown in the interface schematic provide 3kV electrostatic discharge
(ESD) protection using the human body model.
See pin 7.
10
GND2
Digital PLL ground connection. Diodes shown in the interface sche-
matic provide 3kV electrostatic discharge (ESD) protection using the
human body model.
See pin 4.
OSC E
V
CC
OSC B
V
CC
PD
GND
V
CC
TX OUT
MOD IN
RF IN
VCC1
V
CC
1 k
MOD IN
TX OUT
V
CC
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Pin
Function
Description
Interface Schematic
11
VREF P
Bias voltage reference pin for bypassing. The bypass capacitor should
be of appropriate size to provide filtering of the reference crystal fre-
quency and be connected directly to this pin. Diodes shown in the inter-
face schematic provide 3kV electrostatic discharge (ESD) protection
using the human body model.
12
RESNTR-
The RESNTR pins are used to supply DC voltage to the VCO, as well
as to tune the center frequency of the VCO. Equal value inductors
should be connected to this pin and pin 13.
13
RESNTR+
See pin 12.
14
LOOP FLT
Output of the charge pump. An RC network from this pin to ground is
used to establish the PLL bandwidth. Diodes shown in the interface
schematic provide 3kV electrostatic discharge (ESD) protection using
the human body model.
15
LD FLT
This pin is used to set the threshold of the lock-detect circuit. A shunt
capacitor should be used to set an RC time constant with the on-chip
series 1k resistor. This signal is used to clamp (enable or disable) the
MOD IN circuitry. The time constant should be approximately 10 times
the reference period. Diodes shown in the interface schematic provide
3kV electrostatic discharge (ESD) protection using the human body
model.
16
DIV CTRL
Logic "High" input selects divide-by-64 prescaler. Logic "Low" input
selects divide-by-32 prescaler. Diodes shown in the interface sche-
matic provide 3kV electrostatic discharge (ESD) protection using the
human body model.
VREF P
V
CC
RESNTR-
RESNTR+
LOOP FLT
4 k
LOOP FLT
V
CC
V
CC
LD FLT
1 k
V
CC
DIV CTRL
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RF2516 Theory of Operation
Introduction
Short range radio devices are becoming commonplace
in today's environment. The most common examples
are the remote keyless entry systems popular on many
new cars and trucks, and the ubiquitous garage door
opener. Other applications are emerging with the
growth in home security, automation and the advent of
various remote control applications. Typically these
devices have been simplex, or one-way, links. They are
also typically built using surface acoustic wave (SAW)
devices as the frequency control elements. This
approach has been attractive because the SAW
devices have been readily available and a transmitter,
for example, could be built with only a few additional
components. Recently however, RF Micro Devices,
Inc. (RFMD), has introduced several new components
that enable a new class of short-range radio devices
based on the use of crystals and phase-locked loops
for frequency control. These devices are superior in
performance and comparable in cost to the traditional
SAW-based designs. The RF2516 is an example of
such a device. The RF2516 is targeted for applications
such as 315MHz and 433MHz band remote keyless
entry systems and wireless security systems, as well
as other remote control applications.
The RF2516 Transmitter
The RF2516 is a low-cost AM/ASK VHF/UHF transmit-
ter designed for applications operating within the fre-
quency range of 100MHz to 500 MHz. In particular, it is
intended for 315MHz to 433MHz band systems,
remote keyless entry systems, and FCC Part 15.231
periodic transmitters. It can also be used as a local
oscillator signal source. The integrated VCO, phase
detector, prescaler, and reference oscillator require
only the addition of an external crystal to provide a
complete phase-locked loop. In addition to the stan-
dard power-down mode, the chip also includes an
automatic lock-detect feature that disables the trans-
mitter output when the PLL is out-of-lock.
The device is manufactured on a 25GHz Silicon Bipo-
lar-CMOS process and packaged in an industry stan-
dard SSOP-16 plastic package. This, combined with
the low external parts count, enables the designer to
achieve small-footprint, high-performance, low-cost
designs.
The RF2516 is designed to operate from a supply volt-
age ranging from 2.0V to 3.6V, accommodating
designs using three NiCd battery cells, two AAA flash-
light cells, or a lithium button battery. The device is
capable of providing up to +10dBm output power into a
50
load, and is intended to comply with FCC require-
ments for unlicensed remote control transmitters. ESD
protection is provided on all pins except VCO and TX
OUT.
While this device is intended for OOK operation, it is
possible to use narrowband FM. This is accomplished
by modulating the reference oscillator rather than
applying the data to the MOD IN input pin. The MOD
IN pin should be tied high to cause the device to trans-
mit. The deviation will be set by pulling limits of the
crystal. Deviation sufficient for the transmission of
voice and other low data rate signals can therefore be
accomplished. Refer to the Application Schematic in
the data sheet for details.
The RF2516 Functional Blocks
A PLL consists of a reference oscillator, a phase detec-
tor, a loop filter, a voltage controlled oscillator (VCO),
and a programmable divider in the feedback path. The
RF2516 includes all of these internally, except for the
loop filter and the reference oscillator's crystal and two
feedback capacitors.
The reference oscillator is a Colpitts type oscillator.
Pins 1 (OSC B) and 2 (OSC E) provide connections to
a transistor that is used as the reference oscillator. The
Colpitts configuration is a low parts count topology with
reliable performance and reasonable phase noise.
Alternatively, an external signal could be injected into
the base of the transistor. The drive level should, in
either case, be around 500mV
PP
. This level prevents
overdriving the device and keeps the phase noise and
reference spurs to a minimum.
The prescaler divides the VCO frequency by either 64
or 32, using a series of flip-flops, depending upon the
logic level present at the DIV CTRL pin. A high logic
level will select the 64 divisor. A low logic level will
select the 32 divisor. This divided signal is then fed into
the phase detector where it is compared with the refer-
ence frequency.
The RF2516 contains an onboard phase detector and
charge pump. The phase detector compares the
phase of the reference oscillator to the phase of the
VCO. The phase detector is implemented using flip-
flops in a topology referred to as either "digital phase/
frequency detector" or "digital tri-state comparator".
The circuit consists of two D flip-flops whose outputs
are combined with a NAND gate which is then tied to
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