TH72035KLD Melexis Inc, TH72035KLD Datasheet - Page 3

• Manufacturer Part Number: TH72035KLD
• Description: TRANSMITTER, FSK/ASK, 433MHZ, 10QFN
• Manufacturer: Melexis Inc

Specifications of TH72035KLD

• Transmitting Current: 17.3mA
• Data Rate: 40Kbps
• Frequency Range: 850MHz To 930MHz
• Modulation Type: ASK, FSK
• Rf Ic Case Style: QFN
• No. Of Pins: 10
• Supply Voltage Range: 1.95V To 5.5V
• Operating: RoHS Compliant
• Output Power: 9.5dBm
• Rohs Compliant: Yes

1 Theory of Operation
1.1 General
As depicted in Fig.1, the TH72035 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
2 Functional Description
2.1 Crystal Oscillator
A Colpitts crystal oscillator with integrated functional capacitors is used as the reference oscillator for the PLL
synthesizer. The equivalent input capacitance CRO offered by the crystal oscillator input pin ROI is about
18pF. The crystal oscillator is provided with an amplitude control loop in order to have a very stable fre-
quency over the specified supply voltage and temperature range in combination with a short start-up time.
39010 72035
Rev. 009
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
5
4
3
= –11 dBm to +9.5 dBm, either by changing the value of resistor RPS or by varying the
FSKDTA
XOSC
control
mode
2
Fig. 1:
XBUF
7
VEE
Block diagram with external components
PLL
PFD
CP
32
Page 3 of 20
VCC
VCO
10
RPS
PSEL
detector
voltage
PA
6
low
ASKDTA
9
VEE
1
FSK/ASK Transmitter
8
OUT
TH72035
out
can be adjusted in
868/915MHz
matching
antenna
network
Data Sheet
March/08