TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 1 of 10 Data Sheet
Rev. 004 Dec. 2001
Features
! Full y integrate d, PLL- s ta bi lize d VC O
! Flexible frequency range from 310 MHz to 450 MHz
! ASK achieved by on/off keying of inter nal
power amplifier
! FM possible with external varactor
! Wide power supply range from 2.2 V to 5.5 V
! High over-all frequency accuracy
! Very low standby current
! Adjustab le out put po wer ran g e from
-12 dBm to +2 dBm
! Adjustable current consumption from
4.8 mA to 11.5 mA
! Differential output well-suited for loop
antenna
! Conforms to EN 300 220 and similar
standard
Ordering Information
Part No. Temperature Range Package
TH71071 -40 C° to 85 °C SOIC8
Applicati on Examples Pin Descri ption
! Keyless car and central locking
! Low-power telemetry
! Alarm and security systems
! General digital data transmission
! General analog audio signal transmission
! Local oscil lator s ign al gen erati on
LF VEE
PS/DATA
ENTX
RO
VCC
OUT2
OUT1
TH71071
1
2
3
4
8
7
6
5
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 2 of 10 Data Sheet
Rev. 004 Dec. 2001
General Description
The TH71071 ASK transmitter IC is designed for
applications in the European 433MHz industrial-
scientific-medical (ISM) band, according to the EN
300 220 telecommunications standard. It can also
be used for any other system with carrier
frequencies ranging from 310 MHz to 450 MHz
(e.g. for applications in the US 315MHz ISM band).
The transmitter's carrier frequency fc is determined
by the frequency of the reference crystal fref that is
used. The integrated PLL synthesizer ensures that
each RF value , rangin g from 310 MHz to 450 MH z,
can be achieved by using a crystal with reference
frequency according to: fref = fc/N, where N = 32 is
the PLL feedback divider ratio.
Theory of Oper ation
General
As depicted in Fig.1, the TH71071 transmitter
consists of a fully integrated voltage-controlled
oscillator (VCO), a divide-by-32 divider (div32), a
phase-frequency detector (PFD) and a charge
pump. An external loop filter at pin LF determines
the dynamic behaviour of the PLL and suppresses
reference spurious signals.
The VCO’s output signal feeds the power amplifier
(PA). RF signal power Po can be adjusted in six
steps from Po = –12 dBm to +2 dBm either by
changing the value of resistor R1 or by varying the
voltage VPS at pin PS/DATA. The open-collector
differential output (OUT1, OUT2) can be used to
either directly drive a loop antenna or to be
converted to a single-ended impedance by means
of a balanced-to-unbalanced (balun) transformer.
For maximum available output power, the
differential output should be matched to a load of
approx. 1 kΩ.
Bandgap biasing ensures stable operation of the IC
at a power supply range of 2.2 V to 5.5 V.
ASK Modulation
The TH71071 can be ASK-modulated by applying
data direc tly at pin PS. This turns t he PA on and of f
and therefore leads to an ASK signal at the output.
LO Source
Many applications require a stable RF source. For
this purpose, the TH71071 can be used without
modulation as an easy-to-use, PLL-stabilized,
continuous wave (CW) generator.
Frequency Modulation (FM)
For FM operati on an external varactor is required. It
simply acts as a pulling capacitor connected in
series to the crystal. Then the analog modulation
signal, applied through a series resistor, directly
modulates the XOSC.
Mode Control Logic
The mode control logic allows two different modes
of operation as listed in the following table. The
mode control pin ENTX is pulled-down internally.
This guarantees that the whole circuit is shut down
if this pin is left floating.
ENTX Mode Description
0 TX disabled whole circuit in standby
1 TX enable TX active
Table 1: Modes of operation
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 3 of 10 Data Sheet
Rev. 004 Dec. 2001
Block Diagram
Fig. 1: TH71071 block diagram with external components
LF 18VEE
OUT1
OUT2
PA
VCC
7
6
mode
control
VCO
PFD
XOSC
div32
charge
pump
RF1 CF2
CF1
2
RO
XTAL
CX1
PS/DATA 4VCC 5
ENTX
3
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 4 of 10 Data Sheet
Rev. 004 Dec. 2001
Pin Defini tion and Descript i on
Pin No. Name I/O Type Functional Schematic Description
1 LF analog I/O
200
Ω
5p
LF
1
200
Ω
connection to loop filter,
charge pump output,
VCO tuning input
2 RO analog I/O
RO1
2
28p
28p
37k
XOSC connection to XTAL,
Colpitts type crystal
oscillator
3 ENTX input
ENTX
3
1.1k
mode control input, CMOS-
compatib le w ith interna l
pull-down
4 PS/ DATA ana log I/O
PS/DATA
4
200
Ω
20µA
power-select and ASK input,
high-impedance comparator
logic
5 VCC supply positive power supply
6 OUT2 output differential power amplifier
output, open collector
7 OUT1 output
VCC
VEE
VEE
VCC
OUT2
6
VEE
7
OUT1
differential power amplifier
output, open collector
8 VEE ground negative po wer su pp ly
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 5 of 10 Data Sheet
Rev. 004 Dec. 2001
Technical Dat a
Absolute Maximum Ratings
Parameter Symbol Condition Min Max Unit
Supply voltage Vcc -0.3 7.0 V
Input voltage Vin ENTX pin -0.3 VCC+0.3 V
Input current Iin ENTX pin -1.0 1.0 mA
Storage temperature TSTG -40 150 °C
Electrostatic discharge VESD human body model,
MIL STD 833D
method 3015.7
-1.0 +1.0 kV
Normal Operating Conditions
Parameter Symbol Condition Min Max Unit
Supply voltage Vcc 2.2 5.5 V
Operating temperature Ta-40 85 °C
XOSC frequency fref set by the crystal 9.69 14 MHz
VCO frequency fcfc = 32 • fref 310 450 MHz
DC Characteristics
all parameters under normal operating conditions, unless otherwise stated;
typical values at Ta = 23 °C and Vcc = 3 V
Parameter Symbol Condition Min Typ Max Unit
Standby current ISBY ENTX=0 0.05 0.1 µA
Operating current Icc ENTX=1, VPS=1.1V 7 9 10 mA
Input HIGH voltage VHIGH ENTX pin 0.7*Vcc Vcc+0.3 V
Input LOW voltage VLOW ENTX pin -0.3 0.3*Vcc V
Input current Iin ENTX=0 -1 1 µA
Pull down current Ipd ENTX=1 2 8 15 µA
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 6 of 10 Data Sheet
Rev. 004 Dec. 2001
AC Characterist ic s
all parameters under normal operating conditions, unless otherwise stated;
typical values at Ta = 23 °C and Vcc = 3 V;
ENTX = 1, VPS = 1.1V, fc = 433.6 MHz, test circuit shown in Fig. 2
Parameter Symbol Condition Min Typ Max Unit
Output power Po-1 dBm
FM deviation ∆fFM adjustab le with
varactor and VFM ±6kHz
Modulation frequency FM fmod 5kHz
Data rate ASK RASK NRZ 40 kbit/s
Reference spurs Pref @ fc ± fref -44 dBm
Harmonic content Pharm @ 2fc , 3fc , 4fc-40 dBm
Spurious output signal Poff VPS ≤ 0.1V -60 dBm
Phase nois e PN @ fc ± 500kHz -87 dBc/Hz
VCO gain KVCO 200 MHz/V
Charge pum p curr ent ICP ±260 µA
Start-up time ton from ”all OFF” to any
other mode 0.9 ms
Output Power Selection
typical values at Ta = 23 °C and Vcc = 3 V:
ENTX = 1, fc = 433.6 MHz, test circuit shown in Fig. 2
R1 / kΩ
Ω Ω
Ω 07.5 11 15 24 43
R2 / kΩ
Ω Ω
Ω 4.7 4.7 4.7 4.7 4.7
VPS / V ≥
≥≥
≥ 2 1.1 0.9 0.7 0.5 0.3
Icc / mA 11.5 8.6 7.3 6.2 5.3 4.8
Po / dBm 2 -1 -4 -7 -10 -12
Pharm / dBm ≤-40 ≤-40 ≤-40 ≤-45 ≤-45 ≤-50
If the transmitter is operated at any supply voltage Vcc,
the values for R1 and R2 can be calculated as allows:
−•= 1
21 PS
cc
V
V
RR
Crystal Parameter
Parameter Symbol Condition Min Max Unit
Crystal frequency fcrystal fundamental mode, AT 9.69 14 MHz
Load capacitance Cload 10 15 pF
Static capacitance C07pF
Resonance resistance Rm60 Ω
Spurious response aspur -10 dB
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 7 of 10 Data Sheet
Rev. 004 Dec. 2001
Test Cir cuit
Fig. 2: Test circuit for ASK
with 50Ω matching network
Test circuit component list to Fig. 2
Part Size Value Tolerance Description
CF1 0603 10 nF ±10% loop filter capacitor
CF2 0603 56 pF ±10% loop filter capacitor
CX 0603 68 pF ±10% XOSC capacitor
C1 0603 2.7 pF ±5% impedance matching capacitor
C2 0805 100 pF ±5% impedance matching capacitor
C3 0805 3.9 pF ±5% impedance matching capacitor
C4 0603 330 pF ±10% blocking capacitor
C5 0603 330 pF ±10% blocking capacitor
C6 0805 33 nF ±10% blocking capacitor
L1 0603 22 nH ±5% impedan ce mat chi ng inductor
L2 0603 27 nH ±5% impedan ce mat chi ng inductor
L3 0603 33 nH ±5% impedan ce matching indu ctor
RF1 0603 1.5 kΩ±10% loop filter resistor
R1 0603 See output power
selection table ±10% ASK power-select resistor, not requirement at CW mode
R2 0603 See output power
selection table ±10% ASK or CW mode power-select resistor
XTAL HC49/S 13.55 MHz
fundamental wave ±30ppm
calibration
±30ppm temp.
crystal, Cload = 12 pF to 15 pF, C0, max = 7 pF,
Rm, max = 60 Ω
VCC
VEE
OUT1
OUT2
RO
LF
ENTX
PS
DATA
1
3
45
6
7
L1
L2
XTAL
CX
RF1
R2
CF1CF2
8
2
C1
DATA
GND
12
ENTX
GND
VCC
12 3
C4
OUT
C3
L3 C2
R1
C6
VCC
GND
12
C5
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 8 of 10 Data Sheet
Rev. 004 Dec. 2001
Spectrum Plots
All plots depict TH71071‘s typical performance at Vcc = 3.0 V and T a = 23 °C,
derived with the test circuit shown in Fig. 2.
Fig. 3: RF output signal and spurious emissions, CW mode
Fig. 4: Single-sideband phase noise at 500 kHz offset, C W mode
Fig. 5: ASK modulation with RASK = 4 kbit/s NRZ
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 9 of 10 Data Sheet
Rev. 004 Dec. 2001
Package Infor mation
Fig. 6: SOIC8 (Small Outline Package)
all Dimension in mm, coplanarity < 0.1mm
DE1 E A A1 e b L α
αα
α
min 4.80 3.81 5.80 1.32 0.10 1.27 0.36 0.41 0°
max 4.98 3.99 6.20 1.72 0.25 0.46 1.27 8°
all Dimension in inch, coplanarity < 0.004”
min 0.189 0.150 0.2284 0.060 0.0040 0.05 0.014 0.016 0°
max 0.196 0.157 0.2440 0.068 0.0098 0.018 0.050 8°
123
D
E1 E
b
e
A1 A
L
α
TH71071
315/433MHz
ASK Transmitter / LO Source
3901071071 Page 10 of 10 Data Sheet
Rev. 004 Dec. 2001
Your Notes
Important Notice
Devices sold by Melexis are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. Melexis makes no warranty,
express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent
infringem ent. Mel exis res erves the rig ht to c hang e speci ficati ons and p rices at a ny ti me and without n otice . Theref ore, p rior t o designing this product into a
system, it is necessary to check with Melexis for current information. This product is intended for use in normal commercial applications. Applications
requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-
sustaining equipment are specifically not recommended without additional processing by Melexis for each application.
The information furnished by Melexis is believed to be correct and accurate. However, Melexis shall not be liable to recipient or any third party for any
damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interrupt of business or indirect, special incidental or
consequential damages, of any kind, in connection with or arisi ng out of the furnis hing, performance or use of the technic al data herei n. No o bligation or
liability to recipient or any third party shall arise or flow out of Melexis’ rendering of technical or other services.
© 2000 Melexis NV. All rights reserved.
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