u3742bm ATMEL Corporation, u3742bm Datasheet - Page 8

• Manufacturer Part Number: u3742bm
• Description: Uhf Ask/fsk Receiver
• Manufacturer: ATMEL Corporation

8
U3742BM
Figure 7. Temperature Compensation of V
Figure 8. RSSI Characteristic
If R
sensitivity is defined by the value of R
noise ratio of the LNA input. The reduced sensitivity is dependent 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 illustrated in Figure 6 on page 6 and exhibits the best possi-
ble sensitivity.
R
switched from full sensitivity to reduced sensitivity or vice versa at any time. In polling
mode, the receiver will 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 will disappear
when the input signal is lower than defined by the reduced sensitivity. Instead of the
data stream, the pattern according to Figure 9 on page 9 is issued at pin DATA to indi-
cate that the receiver is still active.
Sense
Sense
can be connected to V
is connected to V
0.9
0.8
0.6
0.7
0.5
1.6
1.4
1.3
1.2
1.0
1.5
1.1
-110
50k
105°C
-40°C
I ~ Ig(V
25°C
U3742BM
-100
S
, the receiver operates at a lower sensitivity. The reduced
LNA_IN
S
)
or GND via a microcontroller. The receiver can be
I
-90
max
RSSI
Sense
P
Ref
V
-80
RSSI
RSSI
, the maximum sensitivity by the signal-to-
(dBm)
min
-70
B
47k
180k
min
V
= 60
RSSI_temp_comp.
-60
-50
4735A–RKE–11/03