TDA7200 Datasheet, PDF (31/49 Pages) Infineon Technologies AG – ASK/FSK Single Conversion Receiver

Uc
Us
TDA7200
Applications
T3
Figure 14 Voltage transient on capacitor C13 attached to pin 20
As an example the choice of C18 = 22nF and C13 = 47nF yields
τ₂ = 0.44ms
T₂ = 0.71ms
T₃ = 0.53ms
This means that in this case the inrush current could flow for a duration of 0.64ms but
stops already after 0.49ms when the U_Smax limit has been reached. T₃ should always be
chosen to be shorter than T₂.
It has to be noted finally that during the turn-on duration T₂ the overall device power
consumption is increased by the 220µA needed to charge C13.
The precharge circuit may be disabled if C18 is not equipped. This yields a T₂ close to
zero. Note that the sum of R₄ and R₅ has to be 600kΩ in order to produce 3V at the
THRES pin as this voltage is internally used also as the reference for the FSK
demodulator.
Data Sheet
31
V 1.0, 2007-05-02