TH72031KDC Melexis Inc, TH72031KDC Datasheet - Page 3

• Manufacturer Part Number: TH72031KDC
• Description: 868/915 MHZ, FSK TRANSMITTER
• Manufacturer: Melexis Inc

Specifications of TH72031KDC

• Frequency: 868MHz, 915MHz
• Applications: Alarm and Security Systems, RKE
• Modulation Or Protocol: FSK
• Data Rate - Maximum: 40 kbps
• Power - Output: -11dBm ~ 9dBm
• Current - Transmitting: 5.1mA ~ 13.4mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 1.9 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Memory Size: -
• Other names: Q3477881B

1 Theory of Operation
1.1 General
As depicted in Fig.1, the TH72031 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 (CP). An inter-
nal loop filter determines the dynamic behavior of the PLL and suppresses reference spurious signals. A
Colpitts crystal oscillator (XOSC) is used as the reference oscillator of a phase-locked loop (PLL) synthe-
sizer. The VCO’s output signal feeds the power amplifier (PA). The RF signal power P
four steps from P
voltage V
or to be matched to a 50Ohm load. Bandgap biasing ensures stable operation of the IC at a power supply
range of 1.95 V to 5.5 V.
1.2 Block Diagram
3901072031
Rev. 010
CX1
XTAL
CX2
PS
FSKSW
ENTX
at pin PSEL. The open-collector output (OUT) can be used either to directly drive a loop antenna
ROI
out
4
3
2
= –12 dBm to +9.5 dBm, either by changing the value of resistor RPS or by varying the
FSKDTA
XOSC
control
mode
1
Fig. 1:
XBUF
8
VEE
Block diagram with external components
PLL
PFD
CP
32
Page 3 of 20
VCC
VCO
6
RPS
PSEL
detector
voltage
PA
5
low
7
FSK Transmitter
OUT
TH72031
out
can be adjusted in
868/915MHz
matching
antenna
network
Data Sheet
Jan/09