ata5724p3c-tkqy ATMEL Corporation, ata5724p3c-tkqy Datasheet - Page 7

• Manufacturer Part Number: ata5724p3c-tkqy
• Description: Uhf Ask/fsk Receiver
• Manufacturer: ATMEL Corporation

9248A–RKE–09/11
The output voltage of the RSSI amplifier (VRSSI) is available at pin RSSI. Using the RSSI out-
put signal, the signal strength of different transmitters can be distinguished. The usable input
power range P
Figure 4-1.
The output voltage of the RSSI amplifier is internally compared to a threshold voltage V
V
pin SENS and GND or V
this 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
is defined by the value of R
ratio 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
sensitivity 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
that the receiver is still active (see
Figure 4-2.
Th_red
Sens
Figure 4-2
Sens
Sens
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
“Steady L State Limited DATA Output Pattern” is issued at pin DATA to indicate
RSSI Characteristics Atmel
Steady L State Limited DATA Output Pattern
Ref
is –100dBm to –55dBm.
Atmel ATA5723C/ATA5724C/ATA5728C
-110
DATA
S
S
. The output of the comparator is fed into the digital control logic. By
, the receiver operates at a lower sensitivity. The reduced sensitivity
-100
Sens
S
or GND using a microcontroller. The receiver can be switched
, and the maximum sensitivity is defined by the signal-to-noise
t
DATA_min
RSSI Characteristics
-90
Figure 13-2 on page 30
PIN (dBm)
Section 14. “Data Interface” on page
-80
®
ATA5724C
t
DATA_L_max
-70
-60
“Data Interface”).
Sens
-50
. R
Sens
-40
is connected between
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
Th_red
7
.