TDA5250D2 Datasheet, PDF (22/97 Pages) Infineon Technologies AG – ASK/FSK 868MHz Wireless Transceiver

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TDA 5250 D2
preliminary
Functional Description
3.4.12 Crystal Oscillator
The reference oscillator is an NIC oscillator type (Negative Impedance
Converter) with a crystal operating in serial resonance. The nominal operating
frequency of 18.083MHz and the frequencies for FSK modulation can be
adjusted via 3 external capacitors. Via microcontroller and bus interface the
chip-internal capacitors can be used for finetuning of the nominal and the FSK
modulation frequencies. This finetuning of the crystal oscillator allows to
eliminate frequency errors due to crystal or component tolerances.
3.4.13 Bandgap Reference Circuitry
A Bandgap Reference Circuit provides a temperature stable 1.2V reference
voltage for the device. A power down mode is available to switch off all
subcircuits that are controlled by the bidirectional Powerdown&DataDetect
PwdDD pin (pin 27) as shown in the following table. The supply current in this
mode is typically 100nA.
Table 3-5 PwdDD Pin Operating States
PwdDD
VDD
Ground/VSS
Operating State
Powerdown Mode
Device On
Wireless Components
3 - 12
Specification, July 2002