TDA5211XT Infineon Technologies, TDA5211XT Datasheet - Page 31

• Manufacturer Part Number: TDA5211XT
• Manufacturer: Infineon Technologies

Specifications of TDA5211XT

• Operating Temperature (min): -40C
• Operating Temperature Classification: Automotive
• Product Depth (mm): 4.4mm
• Product Length (mm): 9.7mm
• Operating Supply Voltage (min): 4.5V
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / Rohs Status: Compliant

Wireless Components
4.7 Principle of the Precharge Circuit
In case the data slicer threshold shall be generated with an external RC network
as described in Section 4.5 it is necessary to use large values for the capacitor
C attached to the SLN pin (pin 20) in order to achieve long time constants. This
results also from the fact that the choice of the value for R connected between
the SLP and SLN pins (pins 19 and 20) is limited by the 330k resistor appear-
ing in parallel to R as can be seen in Figure 4-7. Apart from this a resistor value
of 100k
in Section 4.6.1. The resulting startup time constant
In case R is chosen to be 100k
When the device is turned on this time constant dominates the time necessary
for the device to be able to demodulate data properly. In the powerdown mode
the capacitor is only discharged by leakage currents.
In order to reduce the turn-on time in the presence of large values of C a pre-
charge circuit was included in the TDA5211 as shown in the following figure.
Figure 4-10
1
1
= (R // 330k ) · C
= (100k
leads to a voltage offset of 1mv at the comparator input as described
20k
24
// 330k ) · 47nF = 77k
Principle of the precharge circuit
U2
+3.1V
R1
R1+R2=600k
23
Uc>Us
C2
U
th r es h o ld
-
4 - 11
OTA
R2
0 / 240uA
Uc<Us
+2.4V
U2<2.4V : I=240uA
U2>2.4V : I=0
I
load
and C is chosen as 47nF this leads to
-
+
20
· 47nF = 3.6ms
Uc
C
R
19
Us
Data Filter
1
can be calculated with:
Specification, May 2001
ASK/FSK Switch
Applications
TDA 5211
precharge.WMF