ATA3745P3-TGQY Atmel, ATA3745P3-TGQY Datasheet - Page 5

• Manufacturer Part Number: ATA3745P3-TGQY
• Description: IC UHF ASK/FSK RECEIVER 20SOIC
• Manufacturer: Atmel

Specifications of ATA3745P3-TGQY

• Frequency: 310MHz ~ 440MHz
• Sensitivity: -108dBm
• Data Rate - Maximum: 10 kBaud
• Modulation Or Protocol: ASK, FSK
• Applications: RKE, TPM, Security Systems
• Current - Receiving: 7mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-SOIC (0.300", 7.50mm Width)
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• 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: Lead free / RoHS Compliant
• Features: -
• Memory Size: -
• Lead Free Status / Rohs Status: Compliant
• Other names: ATA3745P3-TGQYTR

4901B–RKE–11/07
To determine f
IF frequency is f
filter is tuned by the crystal frequency f
and f
las:
The relation is designed to achieve the nominal IF frequency of f
tions. For applications where f
f
1 MHz. f
rizes the different conditions.
The RF input either from an antenna or from a generator must be transformed to the RF input
pin LNA_IN. The input impedance of that pin is provided in the electrical parameters. The par-
asitic board inductances and capacitances also influence the input matching. The RF receiver
ATA3745 exhibits its highest sensitivity at the best signal-to-noise ratio (SNR) in the LNA.
Hence, noise matching is the best choice for designing the transformation network.
A good practice when designing the network is to start with power matching. From that starting
point, the values of the components can be varied to some extent to achieve the best
sensitivity.
If a SAW is implemented into the input network, a mirror frequency suppression of
These SAWs work best for an intermediate frequency of IF = 1 MHz. The selectivity of the
receiver is also improved by using a SAW. In typical automotive applications, a SAW is used.
Figure 3-2 on page 6
f
without a SAW. The input matching networks shown in
networks for the parameters given in the section
Table 3-1.
MODE
MODE
RF
RF
Conditions
f
f
300 MHz < f
0
365 MHz < f
1
P
RF
RF
Ref
= 433.92 MHz, the MODE must be set to “1”. For other RF frequencies, f
= 433.92 MHz using a SAW.
= 315 MHz, MODE = 0
= 433.92 MHz, MODE = 1
LO
= 40 dB can be achieved. There are SAWs available that exhibit a notch at f = 2 MHz.
=
=
that depends on the logic level at pin MODE. This is described by the following formu-
IF
0 (USA) f
1 (Europe) f
is then dependent on the logical level at pin MODE and on f
RF
RF
LO
Calculation of LO and IF Frequency
< 365 MHz, MODE =
< 450 MHz, MODE =
IF
, the construction of the IF filter must be considered at this point. The nominal
IF
= 1 MHz. To achieve a good accuracy of the filter’s corner frequencies, the
=
IF
--------- -
314
=
f
LO
shows a typical input matching network for f
----------------- -
432.92
f
LO
RF
Figure 3-3 on page 6
= 315 MHz, the MODE must be set to “0”. In the case of
Local Oscillator
Frequency
f
f
f
f
LO
LO
LO
LO
XTO
= 314 MHz
= 432.92 MHz
=
=
. This means that there is a fixed relation between f
-------------------
1
--------------------------- -
1
+
+
f
RF
--------- -
314
f
----------------- -
432.92
RF
1
“Electrical Characteristics” on page
1
Figure 3-3 on page 6
illustrates an input matching to 50
IF
Intermediate Frequency
f
f
f
f
IF
IF
IF
IF
= 1 MHz for most applica-
= 1 MHz
= 1 MHz
=
=
--------- -
314
----------------- -
432.92
RF
f
LO
f
.
RF
LO
Table 3-1
ATA3745
are the reference
= 315 MHz and
IF
is not equal to
23.
summa-
IF
5