TDA5250D2 Datasheet, PDF (78/97 Pages) Infineon Technologies AG – ASK/FSK 868MHz Wireless Transceiver

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TDA 5250 D2
preliminary
Applications
One possible Solution:
t_ON = 15ms, t_OFF= 135ms
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:
D a ta
D a ta
D a ta
D a ta
t [m s]
Case B:
50ms 15ms 135ms
µP enables Receiver
until Data com pleted
Interrupt
due PwdDD
D a ta
D a ta
D a ta
D a ta
t [m s]
Case C:
50ms 15ms 135ms
µP enables Receiver
until Data com pleted
Interrupt
due PwdDD
D a ta
D a ta
D a ta
D a ta
t [m s]
50ms
15ms 135ms
... Receiver enabled
µP enables Receiver
until Data com pleted
Interrupt
due PwdDD
Figure 4-35 3 possible timings
data_timing021.wmf
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 5.4 at pin12 and 13 are recommended. Further information on
calculating these components can be taken from Section 4.6.2.
Wireless Components
4 - 38
Specification, July 2002