ATA5724 ATMEL [ATMEL Corporation], ATA5724 Datasheet - Page 7

• Manufacturer Part Number: ATA5724
• Description: UHF ASK/FSK Receiver
• Manufacturer: ATMEL [ATMEL Corporation]

9106E–RKE–07/08
Figure 4-1.
The output voltage of the RSSI amplifier is internally compared to a threshold voltage V
V
SENS and GND or V
means, it is possible to operate the receiver at a lower sensitivity.
If R
nect the pin SENS directly to GND to get the maximum sensitivity.
If R
defined by the value of R
of the LNA input. The reduced sensitivity depends on the signal strength at the output of the
RSSI amplifier.
Since different RF input networks may exhibit slightly different values for the LNA gain, the sen-
sitivity values given in the electrical characteristics refer to a specific input matching. This
matching is described and illustrated in
R
from full sensitivity to reduced sensitivity or vice versa at any time. In polling mode, the receiver
does not wake up if the RF input signal does not exceed the selected sensitivity. If the receiver is
already active, the data stream at pin DATA disappears when the input signal is lower than
defined by the reduced sensitivity. Instead of the data stream, the pattern according to
4-2
receiver is still active (see
Figure 4-2.
Th_red
Sens
Sens
Sens
“Steady L State Limited DATA Output Pattern” is issued at pin DATA to indicate that the
can be connected to V
is determined by the value of the external resistor R
is connected to V
is connected to GND, the receiver switches to full sensitivity. It is also possible to con-
3.5
2.5
1.5
3
2
1
-120
RSSI Characteristics ATA5724
Steady L State Limited DATA Output Pattern
-110
S
. The output of the comparator is fed into the digital control logic. By this
DATA
S
Sens
, the receiver operates at a lower sensitivity. The reduced sensitivity is
Figure 13-2 on page 30
-100
, and the maximum sensitivity is defined by the signal-to-noise ratio
S
or GND using a microcontroller. The receiver can be switched
t
DATA_min
RSSI Characteristics
-90
PIN (dBm)
Section 14. “Data Interface” on page
-80
ATA5723/ATA5724/ATA5728
t
DATA_L_max
-70
“Data Interface”).
-60
Sens
-50
. R
Sens
-40
is connected between pin
32.
4.5V -40
5V -40
5.5V -40
4.5V 25
5V 25
5.5V 25
4.5V 85
5V 85
5.5V 85
4.5V 105
5V 105
5.5V 105
˚
˚
˚
C
C
C
˚
˚
˚
˚
˚
˚
˚
C
C
C
C
C
C
C
˚
˚
C
C
Figure
Th_red
7
.