tda5251f1 Infineon Technologies Corporation, tda5251f1 Datasheet - Page 61

• Manufacturer Part Number: tda5251f1
• Description: Ask/fsk 315mhz Wireless Transceiver
• Manufacturer: Infineon Technologies Corporation

Confidential
Figure 3-22
3.6
The data slicer is an analog-to-digital converter. It is necessary to generate a threshold value for the
negative comparator input (data slicer). The TDA5251 offers an RC integrator and a peak detector
which can be selected via logic. Independent of the choice, the peak detector outputs are always
active.
3.6.1
Table 3-12
Necessary external component (Pin14): C
This integrator generates the mean value of the data filter output. For a stable threshold value, the
cut-off frequency has to be lower than the lowest signal frequency. The cutoff frequency results from
the internal resistance R=100kW and the external capacitor C
Cut-off frequency:
Component calculation: (rule of thumb)
T
Preliminary Specification
L
D15
Bit
– longest period of no signal change
Data Slicer - Slicing Level
RC Integrator
Sub Address 00H: CONFIG
Function
SLICER
Typ. RSSI Level (Eval Board) @3V
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
-120
C
f
-110
SLC
cut
-
³
off
-100
100
=
3
0= LP, 1= Peak Detector
2
×
-90
T
k
p
L
W
×
100
-80
SLC
Description
RF /dBm
1
k
-70
W
61
×
C
-60
SLC
-50
<
Min
high gain
low gain
-40
{
f
SLC
-30
Signal
on Pin14.
-20
}
ADC
Default
0
TDA5251 F1
Version 1.0
Application
[3 – 30]
[3 – 31]
2003-02-18
SET
0
RSSI.wmf