T5744-TKS Atmel, T5744-TKS Datasheet - Page 7

• Manufacturer Part Number: T5744-TKS
• Description: RF Transceiver UHF ASK Receiver IC
• Manufacturer: Atmel

Specifications of T5744-TKS

• Operating Supply Voltage: 5 V
• Mounting Style: SMD/SMT
• Package / Case: SSO-20
• Minimum Operating Temperature: - 40 C
• 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: Lead free / RoHS Compliant

4.4
4521C–RKE–05/05
ASK Demodulator and Data Filter
Figure 4-1.
The signal coming from the RSSI amplifier is converted into the raw data signal by the ASK
demodulator.
An automatic threshold control circuit (ATC) is employed to set the detection reference voltage
to a value where a good signal-to-noise ratio is achieved. This circuit also implies the effective
suppression of any kind of inband noise signals or competing transmitters. If the S/N ratio
exceeds 10 dB, the data signal can be detected properly.
The output signal of the demodulator is filtered by the data filter before it is fed into the digital
signal processing circuit. The data filter improves the S/N ratio as its passband can be adopted
to the characteristics of the data signal. The data filter consists of a 1st-order highpass and a
1st-order lowpass filter.
The highpass filter cut-off frequency is defined by an external capacitor connected to pin CDEM.
The cut-off frequency of the highpass filter is defined by the following formula:
Recommended values for CDEM are given in the electrical characteristics.
The cut-off frequency of the lowpass filter is defined by the selected baudrate range
(BR_Range). BR_Range is defined by the pins BR_0 and BR_1. BR_Range must be set in
accordance to the used baudrate.
Table 4-1.
fcu_DF
=
---------------------------------------------------- -
2
BR_1
RSSI Characteristics
Definition of BR_Range by the Pins BR_0 and BR_1
0
0
1
1
R
1
1
3.0
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
CDEM
-130.0
-110.0
105°C
25°C
T
-90.0
amb
BR_0
= 40°C
P
0
1
0
1
Ref
min.
(dBm)
-70.0
max.
-50.0
-30.0
BR_Range
0
1
2
2
T5744
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