T48C862M-R3-TNQ Atmel, T48C862M-R3-TNQ Datasheet - Page 7

• Manufacturer Part Number: T48C862M-R3-TNQ
• Description: IC MON TIRE PRESS 315MHZ 24SOIC
• Manufacturer: Atmel

Specifications of T48C862M-R3-TNQ

• Frequency: 315MHz
• Modulation Or Protocol: FM, FSK
• Data Rate - Maximum: 32 kBaud
• Power - Output: 10dBm
• Current - Transmitting: 9.5mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Memory Size: 1KB EEPROM, 1KB RAM
• Voltage - Supply: 2 V ~ 4 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 24-SOIC (0.200", 5.30mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Applications: -

CLK Output
Clock Pulse Take Over
Output Matching and Power
Setting
4554A–4BMCU–02/03
Figure 4. Tolerances of Frequency Modulation
Using C
capacitances on each side of the crystal of C
capacitance of the crystal of C
FSK deviation of ±21.5 kHz typical with worst case tolerances of ±16.25 kHz to
±28.01 kHz results.
An output CLK signal is provided for a connected microcontroller, the delivered signal is
CMOS compatible if the load capacitance is lower than 10 pF.
The clock of the crystal oscillator can be used for clocking the microcontroller. Atmel’s
M4xCx9x has the special feature of starting with an integrated RC-oscillator to switch on
the PLL transmitter block with ENABLE = H, and after 1 ms to assume the clock signal
of the transmission IC, so the message can be sent with crystal accuracy.
The output power is set by the load impedance of the antenna. The maximum output
power is achieved with a load impedance of Z
low resistive path to V
The delivered current pulse of the power amplifier is 9 mA and the maximum output
power is delivered to a resistive load of 400 W if the 1.0 pF output capacitance of the
power amplifier is compensated by the load impedance.
An optimum load impedance of:
Z
power of 8 dBm.
The load impedance is defined as the impedance seen from the PLL transmitter block’s
ANT1, ANT2 into the matching network. Do not confuse this large signal load imped-
ance with a small signal input impedance delivered as input characteristic of RF
amplifiers and measured from the application into the IC instead of from the IC into the
application for a power amplifier.
Less output power is achieved by lowering the real parallel part of 400 W where the
parallel imaginary part should be kept constant.
Output power measurement can be done with the circuit shown in Figure 5. Note that
the component values must be changed to compensate the individual board parasitics
until the PLL transmitter block has the right load impedance Z
Also the damping of the cable used to measure the output power must be calibrated.
Load
= 400 W || j/(2 ´ p 1.0 pF) = (255 + j192) W thus results for the maximum output
4
= 8.2 pF ±5%, C
XTAL
V
S
S
~
to deliver the DC current.
5
= 10 pF ±5%, a switch port with C
0
C
= 3.2 pF ±10% and a crystal with C
Stray1
Crystal equivalent circuit
C
M
L
C
M
0
Load,opt
Stray1
R
S
= (255 + j192) W. There must be a
= C
Stray2
C
Stray2
C
5
Switch
= 1 pF ±10%, a parallel
Load,opt
C
T48C862-R3
Switch
C
4
= 3 pF ±10%, stray
M
= 13 fF ±10%, an
= (255 + j192) W.
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