SDA4331X Datasheet, PDF (5/13 Pages) Siemens Semiconductor Group – PLL with I2C Bus for AM/FM Receivers

SDA 4331X
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Functional Description
The SDA 4331X is a radio PLL controlled via I²C Bus for frequency synthesis in the AM
and FM range.
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Circuit Description
The reference frequency for the PLL is derived from the quartz oscillator OSC¹⁾. The
R-prescaler can be adapted to quartz frequencies of 4, 8 or 10.25 MHz, respectively,
yielding an internal 50 kHz reference. Programming the R-counter sets the phase
detector reference frequency to 1, 5 or 10 kHz in the AM mode or to 12.5, 25 or 50 kHz
in the FM mode. The VCO frequency is set by programming the A/N-counter which
operates as dual-modulus counter for FM and AM using a divide by 4/5 swallow counter.
The phase detector drives two different charge pumps for AM and FM mode. Additional
source followers are connected to the charge pump. There are four programmable
current levels for each charge pump. The supply voltage for the charge pump and the
source followers is supplied via the V_DD2 pin and can reach 10 V maximum. AM/FM is an
open drain output as well as the additional outputs SA1 … SA4 which are controlled by
I²C Bus.
The I²C Bus interface provides slave receiver functions. There are two addresses
selected by the A0 pin. The I²C-protocol (see diagram 1) contains one string for
programming all counters and functions. The transfer may be stopped optionally after
each word if the remaining functions are not to be altered. After power ON all control
signals are undefined, so that the complete write sequence must be executed.
1) _{The power dissipation of the quartz is given by:}
P_v = 2 × R₁ (Π × f_Q × (C_O + C_L) × V_DD)²
R₁ … Series resistance of the quartz
f_Q … Quartz frequency
C_O … Parallel capacitance of the quartz
C_L … Load capacitance, including input capacitance of the IC
Semiconductor Group
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04.96