T48C862M-R3-TNS Atmel, T48C862M-R3-TNS Datasheet - Page 6

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

Specifications of T48C862M-R3-TNS

• 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: -

General Description
Functional
Description
ASK Transmission
FSK Transmission
6
T48C862-R3
This fully-integrated PLL transmitter that allows particularly simple, low-cost RF minia-
ture transmitters to be assembled. The VCO is locked to 32 f
crystal is needed for a 315 MHz transmitter. All other PLL and VCO peripheral elements
are integrated.
The XTO is a series resonance oscillator so that only one capacitor together with a
crystal connected in series to GND are needed as external elements.
The crystal oscillator together with the PLL needs maximum <1 ms until the PLL is
locked and the CLK output is stable. A wait time of ³ 1 ms until the CLK is used for the
microcontroller and the PA is switched on.
The power amplifier is an open-collector output delivering a current pulse which is nearly
independent from the load impedance. The delivered output power is controlled via the
connected load impedance.
This output configuration enables a simple matching to any kind of antenna or to 50 W. A
high power efficiency of h = P
an optimized load impedance of Z
If ENABLE = L and PA_ENABLE = L, the circuit is in standby mode consuming only a
very small amount of current so that a lithium cell used as power supply can work for
several years.
With ENABLE = H, the XTO, PLL and the CLK driver are switched on. If PA_ENABLE
remains L, only the PLL and the XTO are running and the CLK signal is delivered to the
microcontroller. The VCO locks to 32 times the XTO frequency.
With ENABLE = H and PA_ENABLE = H, the PLL, XTO, CLK driver and the power
amplifier are on. With PA_ENABLE, the power amplifier can be switched on and off,
which is used to perform the ASK modulation.
The PLL transmitter block is activated by ENABLE = H. PA_ENABLE must remain L for
t ³ 1 ms, then the CLK signal can be taken to clock the microcontroller and the output
power can be modulated by means of pin PA_ENABLE. After transmission,
PA_ENABLE is switched to L and the microcontroller switches back to internal clocking.
The PLL transmitter block is switched back to standby mode with ENABLE = L.
The PLL transmitter block is activated by ENABLE = H. PA_ENABLE must remain L for
t ³ 1 ms, then the CLK signal can be taken to clock the microcontroller and the power
amplifier is switched on with PA_ENABLE = H. The chip is then ready for FSK modula-
tion. The microcontroller starts to switch on and off the capacitor between the XTAL load
capacitor and GND with an open-drain output port, thus changing the reference
frequency of the PLL. If the switch is closed, the output frequency is lower than if the
switch is open. After transmission PA_ENABLE is switched to L and the microcontroller
switches back to internal clocking. The PLL transmitter block is switched back to
standby mode with ENABLE = L.
The accuracy of the frequency deviation with XTAL pulling method is about ±25% when
the following tolerances are considered.
out
/(I
Load
S,PA
= (255 + j192) W is used at 3 V supply voltage.
V
S
) of 40% for the power amplifier results when
XTAL
, thus, a 9.8438 MHz
4554A–4BMCU–02/03