ATA5743P3-TGQY Atmel, ATA5743P3-TGQY Datasheet - Page 9

• Manufacturer Part Number: ATA5743P3-TGQY
• Description: IC RCVR ASK/FSK 300KHZ 20SOIC
• Manufacturer: Atmel

Specifications of ATA5743P3-TGQY

• Frequency: 300MHz ~ 450MHz
• Sensitivity: -110dBm
• Data Rate - Maximum: 10 kBaud
• Modulation Or Protocol: ASK, FSK
• Applications: RKE, Telemetering, Security Technology
• Current - Receiving: 7.5mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 20-SOIC (0.300", 7.50mm Width)
• 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
• Features: -
• Memory Size: -
• Lead Free Status / Rohs Status: Compliant

5.3
4839B–RKE–08/05
FSK/ASK Demodulator and Data Filter
Figure 5-1.
The signal coming from the RSSI amplifier is converted into the raw data signal by the ASK/FSK
demodulator. The operating mode of the demodulator is set via the bit ASK/_FSK in the
OPMODE register. Logic ‘L’ sets the demodulator to FSK, applying ‘H’ to ASK mode.
In ASK mode, an automatic threshold control circuit (ATC) is used to set the detection reference
voltage to a value where a good SNR is achieved. This circuit effectively suppresses any kind of
inband noise signals or competing transmitters. If the SNR (ratio to suppress inband noise sig-
nals) exceeds 10 dB, the data signal can be detected properly.
The FSK demodulator is intended to be used for an FSK deviation of 10 kHz
FSK mode the data signal can be detected if the SNR (ratio to suppress inband noise signals)
exceeds 2 dB. This value is guaranteed for all modulation schemes of a disturber signal.
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 SNR as its passband can be adopted to
the characteristics of the data signal. The data filter consists of a 1
2
The high-pass filter cut-off frequency is defined by an external capacitor connected to pin
CDEM. The cut-off frequency of the high-pass filter is defined by the following formula:
In self-polling mode, the data filter must settle very rapidly to achieve a low current consumption.
Therefore, CDEM cannot be increased to very high values if self-polling is used. On the other
hand, CDEM must be large enough to meet the data filter requirements according to the data
signal. Recommended values for CDEM are given in the electrical characteristics.
The cut-off frequency of the low-pass filter is defined by the selected baud-rate range
(BR_Range). The BR_Range is defined in the OPMODE register (refer to section
of the Receiver” on page
The ATA5743 is designed to operate with data coding where the DC level of the data signal is
50%. This is valid for Manchester and Bi-phase coding. If other modulation schemes are used,
the DC level should always remain within the range of V
then, the sensitivity will be reduced by up to 2 dB.
Each BR_Range is also defined by a minimum and a maximum edge-to-edge time (t
These limits are defined in the electrical characteristics; to maintain full sensitivity of the
receiver, they should not be exceeded.
fcu_DF
nd
-order low-pass filter.
=
------------------------------------------------------------ -
2
Steady L State Limited DATA Output Pattern
DATA
30 k
1
24). The BR_Range must be set in accordance to the used baud rate.
t
CDEM
DATA_min
t
DATA_L_max
DC_min
= 33% and V
st
-order high-pass and a
DC_max
ATA5743
f 100 kHz. In
“Configuration
= 66%. Even
ee_sig
).
9