TDA5250D2_07 Datasheet, PDF (73/94 Pages) Infineon Technologies AG – ASK/FSK 868MHz Wireless Transceiver

TDA5250 D2
Version 1.7
Application
This gives 15ms ON time of a total period of 150ms which results in max. 0.9mA mean current
consumption in Self Polling Mode. The resulting worst case timing is shown in the following figure:
Case A:
Data
Data
Data
Data
t [ms]
Case B:
50ms 15ms 135ms
µP enables Receiver
until Data completed
Interrupt
due PwdDD
Data
Data
Data
Data
t [ms]
Case C:
50ms 15ms 135ms
µP enables Receiver
until Data completed
Interrupt
due PwdDD
Data
Data
Data
Data
t [ms]
50ms
15ms 135ms
... Receiver enabled
µP enables Receiver
until Data completed
Interrupt
due PwdDD
data_timing021.wmf
Figure 3-35 3 possible timings
Description:
Assumption: the ON time comes right after the first frame (Case A). If OFF time is 135ms the
receiver turns on during Sync-pulses and the PwdDD- pulse wakes up the µP.
If the ON time is in the center of the 50ms gap of transmission (Case B), the Data Detect Logic will
wake up the µP 135ms later.
If ON time is over just before Sync-pulses (Case C), next ON time is during Data transmission and
Data Detect Logic will trigger a PwdDD- pulse to wake up the µP.
Note: In this example it is recommended to use the Peak Detector for slicer threshold generation,
because of its fast attack and slow release characteristic. To overcome the data zero gap of 50ms
larger external capacitors than noted in Section 4.4 at pin12 and 13 are recommended. Further
information on calculating these components can be taken from Section 3.6.2.
3.10
Sensitivity Measurements
3.10.1 Test Setup
The test setup used for the measurements is shown in the following figure. In case of ASK
modulation the Rohde & Schwarz SMIQ generator, which is a vector signal generator, is connected
to the I/Q modulation source AMIQ. This "baseband signal generator" is in turn controlled by the PC
Data Sheet
73
2007-02-26