TH72005 Datasheet PDF - Melexis
| Part Number | TH72005 | |
| Description | FSK/ASK Transmitter | |
| Manufacturers | Melexis | |
| Logo |  |
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There is a preview and TH72005 download ( pdf file ) link at the bottom of this page. Total 20 Pages | ||
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TH72005
315MHz
FSK/ASK Transmitter
Features
! Fully integrated PLL-stabilized VCO
! Frequency range from 290 MHz to 350 MHz
! Single-ended RF output
! FSK through crystal pulling allows modulation
from DC to 40 kbit/s
! High FSK deviation possible for wideband data
transmission
! ASK achieved by on/off keying of internal
power amplifier up to 40 kbit/s
! Wide power supply range from 1.95 V to 5.5 V
! Very low standby current
! On-chip low voltage detector
! High over-all frequency accuracy
! FSK deviation and center frequency
independently adjustable
! Adjustable output power range from
-12 dBm to +11 dBm
! Adjustable current consumption from
3.2 mA to 10.3 mA
! Conforms to FCC part 15 and similar standards
! 10-pin Quad Flat No-Lead Package (QFN)
Ordering Information
Part Number
Temperature Code
TH72005
K (-40 °C to 125 °C)
Package Code
LD (10L QFN 3x3 Dual)
Delivery Form
120 pc/tray
5000 pc/T&R
Application Examples
! General digital data transmission
! Tire Pressure Monitoring Systems (TPMS)
! Remote Keyless Entry (RKE)
! Wireless access control
! Alarm and security systems
! Garage door openers
! Remote Controls
! Home and building automation
! Low-power telemetry systems
Pin Description
ASKDTA
FSKDTA
FSKSW
ROI
ENTX
top
TH72005
VCC
VEE
OUT
VEE
PSEL
bottom
10 1
92
83
74
65
General Description
The TH72005 FSK/ASK transmitter IC is designed for applications in the 315 MHz industrial-scientific-
medical (ISM) band. It can also be used for any other system with carrier frequencies ranging from
290 MHz to 350 MHz.
The transmitter's carrier frequency fc is determined by the frequency of the reference crystal fref. The inte-
grated PLL synthesizer ensures that carrier frequencies, ranging from 290 MHz to 350 MHz, can be
achieved. This is done by using a crystal with a reference frequency according to: fref = fc/N, where N = 32 is
the PLL feedback divider ratio.
39010 72005
Rev. 008
Page 1 of 20
Data Sheet
June/07
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2.4 ASK Modulation
The PLL transmitter can be ASK-modulated by
applying a data stream directly at the pin
ASKDTA. This turns the internal current
sources of the power amplifier on and off and
therefore leads to an ASK signal at the output.
TH72005
315MHz
FSK/ASK Transmitter
ASKDTA
0
1
Description
Power amplifier is turned off
Power amplifier is turned on (according
to the selected output power step)
2.5 Output Power Selection
The transmitter is provided with an output power selection feature. There are four predefined output power
steps and one off-step accessible via the power selection pin PSEL. A digital power step adjustment was
chosen because of its high accuracy and stability. The number of steps and the step sizes as well as the
corresponding power levels are selected to cover a wide spectrum of different applications.
The implementation of the output power control
logic is shown in figure 4. There are two
matched current sources with an amount of
about 8 µA. One current source is directly ap-
plied to the PSEL pin. The other current source
is used for the generation of reference voltages
with a resistor ladder. These reference voltages
are defining the thresholds between the power
steps. The four comparators deliver thermome-
ter-coded control signals depending on the
voltage level at the pin PSEL. In order to have a
certain amount of ripple tolerance in a noisy
environment the comparators are provided with
a little hysteresis of about 20 mV. With these
control signals, weighted current sources of the
power amplifier are switched on or off to set the
desired output power level (Digitally Controlled
Current Source). The LOCK, ASK signal and
the output of the low voltage detector are gating
this current source.
RPS
PSEL
ASKDTA
&
&
&&&
OUT
Fig. 4: Block diagram of output power control circuitry
There are two ways to select the desired output power step. First by applying a DC voltage at the pin PSEL,
then this voltage directly selects the desired output power step. This kind of power selection can be used if
the transmission power must be changed during operation. For a fixed-power application a resistor can be
used which is connected from the PSEL pin to ground. The voltage drop across this resistor selects the de-
sired output power level. For fixed-power applications at the highest power step this resistor can be omitted.
The pin PSEL is in a high impedance state during the “TX standby” mode.
2.6 Lock Detection
The lock detection circuitry turns on the power amplifier only after PLL lock. This prevents from unwanted
emission of the transmitter if the PLL is unlocked.
2.7 Low Voltage Detection
The supply voltage is sensed by a low voltage detect circuitry. The power amplifier is turned off if the supply
voltage drops below a value of about 1.85 V. This is done in order to prevent unwanted emission of the
transmitter if the supply voltage is too low.
39010 72005
Rev. 008
Page 5 of 20
Data Sheet
June/07
Preview 5 Page |
Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for TH72005 electronic component. |
| Information | Total 20 Pages | |
| Link URL | [ Copy URL to Clipboard ] | |
| Download | [ TH72005.PDF Datasheet ] | |
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