T5743N-TG Atmel, T5743N-TG Datasheet - Page 3

• Manufacturer Part Number: T5743N-TG
• Manufacturer: Atmel

Specifications of T5743N-TG

• Operating Frequency (max): 450000kHz
• Operating Temperature (min): -40C
• Operating Temperature (max): 105C
• Operating Temperature Classification: Industrial
• Operating Supply Voltage (min): 4.5V
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / Rohs Status: Not Compliant

Block Diagram
RF Front End
The RF front end of the receiver is a heterodyne configu-
ration that converts the input signal into a 1-MHz IF
signal. According to figure 3, the front end consists of an
LNA (low noise amplifier), LO (local oscillator), a mixer
and an RF amplifier.
The LO generates the carrier frequency for the mixer via
a PLL synthesizer. The XTO (crystal oscillator) generates
the reference frequency f
trolled oscillator) generates the drive voltage frequency
f
LF. f
compared to f
current output of the phase frequency detector is
connected to a passive loop filter and thereby generates
Rev. A3, 17-Dec-01
LO
for the mixer. f
LO
is divided by factor 64. The divided frequency is
XTO
LNAGND
MIXVCC
LNA_IN
CDEM
AGND
DGND
by the phase frequency detector. The
AVCC
LO
SENS
is dependent on the voltage at Pin
XTO
. The VCO (voltage-con-
LNA
RSSI
and data filter
Demodulator
FSK/ASK–
4. Order
IF Amp
IF Amp
3 MHz
3 MHz
LPF
LPF
Figure 3. Block diagram
Limiter out
Dem_out
Sensitivity
reduction
the control voltage V
configuration V
equal to f
using the following formula: f
The XTO is a one-pin oscillator that operates at the series
resonance of the quartz crystal. According to figure 4, the
crystal should be connected to GND via a capacitor CL.
The value of that capacitor is recommended by the crystal
supplier. The value of CL should be optimized for the
individual board layout to achieve the exact value of f
and hereby of f
of receiving bandwidth, the accuracy of the crystal and
the XTO must be considered.
f
VCO
64
Standby logic
Polling circuit
XTO
control logic
FE
and
. If f
Data
interface
LO
LF
LO
XTO
. When designing the system in terms
CLK
is controlled in a way that f
is determined, f
LF
for the VCO. By means of that
XTO
IC_ACTIVE
DATA
POLLING/_ON
TEST
DATA_CLK
MODE
DVCC
LFGND
LFVCC
XTO
LF
XTO
T5743N
= f
LO
can be calculated
/64
LO
3 (34)
/64 is
XTO