TDA 5210
Applications
Uc
Us
T3
e-Fkt2.WMF
Figure 4-12 Voltage transient on capacitor C attached to pin 20
As an example the choice of C2 = 22nF and C = 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 USmax 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 C.
The precharge circuit may be disabled if C2 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 pro-
duce 3V at the THRES pin as this voltage is internally used also as the refer-
ence for the FSK demodulator.
Wireless Components
4 - 13
Specification, May 2001
INFINEON [ Infineon ]
