TDA5212XT Infineon Technologies, TDA5212XT Datasheet - Page 32

• Manufacturer Part Number: TDA5212XT
• Manufacturer: Infineon Technologies

Specifications of TDA5212XT

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• 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 Ω resistor appear-
ing in parallel to R as can be seen in Figure 4-6. Apart from this a resistor value
of 100k Ω leads to a voltage offset of 1mv at the comparator input as described
in Section 4.6.1. The resulting startup time constant τ
In case R is chosen to be 100k Ω and C is chosen as 47nF this leads to
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 TDA5210 as shown in the following figure.
Figure 4-10
20k
24
Principle of the precharge circuit
U2
τ
+3.1V
1
R1
R1+R2=600k
=
23
(
Uc>Us
100
C2
U
th r es h o ld
-
OTA
4 - 11
k
R2
Ω
0 / 240uA
Uc<Us
||
+2.4V
330
U2<2.4V : I=240uA
U2>2.4V : I=0
τ
I
1
k
load
Ω
=
)
(
×
R
-
+
20
47
||
330
nF
Uc
C
k
R
=
Ω
77
19
Us
)
×
k
C
Ω
Data Filter
×
47
Specification, December 2006
nF
1
can be calculated with:
=
ASK/FSK Switch
3
6 .
ms
Applications
TDA 5212
precharge.WMF