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PDF EVB72036 Data sheet ( Hoja de datos )
| Número de pieza | EVB72036 | |
| Descripción | 868/915MHz FSK/ASK Transmitter Evaluation Board Description | |
| Fabricantes | Melexis Microelectronic Systems | |
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Hay una vista previa y un enlace de descarga de EVB72036 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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EVB72036
868/915MHz FSK/ASK Transmitter
Evaluation Board Description
Features
! Fully integrated PLL-stabilized VCO
! Frequency range from 850 MHz to 930 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
www.DataSheet4U.copmower amplifier up to 40 kbit/s
! Wide power supply range from 1.95 V to 5.5 V
! Very low standby current
! Microcontroller clock output
! On-chip low voltage detector
! High over-all frequency accuracy
! FSK deviation and center frequency
! independently adjustable
! Adjustable output power range from
-11 dBm to +9.5 dBm
! Adjustable current consumption from
5.5 mA to 13.8 mA
! Conforms to EN 300 220 and similar standards
Ordering Information
Part No. (see paragraph 5)
EVB72036-868-FSK-C
EVB72036-915-FSK-C
Note: EVB default population is FSK, ASK modification according to section 3.1.
RYApplication Examples
A! General digital data transmission
IN! Tire Pressure Monitoring Systems (TPMS)
! Remote Keyless Entry (RKE)
! Wireless access control
IM! Alarm and security systems
L! Garage door openers
! Remote Controls
E! Home and building automation
PR! Low-power telemetry systems
Evaluation Board Example
General Description
The TH72036 evaluation board is designed to demonstrate the performance of the transmitter IC for conduc-
tive measurements. The power amplifier is matched to 50 Ohms by means of a π-matching network to oper-
ate at a resonant frequency of 868 and 915 MHz.
The EVB72036 also features a clock output applicable to drive a microcontroller. The clock frequency can be
selected by an external logic signal.
3901272036 01
Rev. 002
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EVB Description
June/07
1 page  
EVB72036
868/915MHz FSK/ASK Transmitter
Evaluation Board Description
2.4 ASK Modulation
The TH72036 can be ASK-modulated by applying data directly at pin PSEL. This turns the PA on and off
which leads to an ASK signal at the output.
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
www.DataSheetc4hUo.csoemn 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- RPS
plied to the PSEL pin. The other current source
is used for the generation of reference voltages
with a resistor ladder. These reference voltages PSEL
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
Ythe output of the low voltage detector are gating
this current source.
OUT
Fig. 4: Block diagram of output power control circuitry
ARThere 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
INthe 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-
IMsired 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.
REL2.6 Lock Detection
PThe 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.
3901272036 01
Rev. 002
Page 5 of 12
EVB Description
June/07
5 Page 
Your Notes
www.DataSheet4U.com
EVB72036
868/915MHz FSK/ASK Transmitter
Evaluation Board Description
PRELIMINARY
3901272036 01
Rev. 002
Page 11 of 12
EVB Description
June/07
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet EVB72036.PDF ] | |
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