TH72016KLD Melexis Inc, TH72016KLD Datasheet - Page 5

• Manufacturer Part Number: TH72016KLD
• Description: TRANSMITTER, FSK/ASK, 433MHZ, 10QFN
• Manufacturer: Melexis Inc

Specifications of TH72016KLD

• Transmitting Current: 14.5mA
• Data Rate: 40Kbps
• Frequency Range: 380MHz To 450MHz
• 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: 10dBm
• Rohs Compliant: Yes

TH72016
433MHz
FSK/ASK Transmitter
2.4 ASK Modulation
The TH72016 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
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-
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
OUT
desired output power level (Digitally Controlled
Current Source). The LOCK signal and the
output of the low voltage detector are gating
Fig. 4:
Block diagram of output power control circuitry
this current source.
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 72016
Page 5 of 16
Data Sheet
Rev. 007
March/08