MC44864M Ver la hoja de datos (PDF) - Motorola => Freescale

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MC44864M

PLL TUNING CIRCUIT WITH 1.3 GHz PRESCALER AND D/A CONVERTERS

Motorola => Freescale 

MC44864

FUNCTIONAL DESCRIPTION

A representative block diagram and a typical system

application are shown in Figures 4 and 5. A discussion of the

features and function of the internal blocks is given below.

Automatic Tuner Alignment

The circuit generates the tuning voltage through the PLL.

The output voltages of the D/A converters are equal to the

tuning voltage plus a positive or negative offset of up to 31

steps. During the automatic alignment one first lets the PLL

lock to the appropriate frequency and then searches for the

optimum value of the other varactor voltages. The digital

word for each voltage value is stored in a nonvolatile memory

(NVM). Hence, for each frequency point to be adjusted, three

times 6 bits of information have to be stored (plus 2 bits for

the DAC range).

The information stored in the NVM reflects the

characteristic of the individual tuner. For this reason, the

NVM is preferably situated inside the tuner and is also

controlled by the I2C Bus.

Figure 4. Block Diagram

DA3

DA2

DA1

VTUN

39 n

1.0 n

Bands and

Controls Out

17 16 15 14

B7 B5 B3 B1

Buffers

1.0 n

8

Amp 4

1.0 n

7

Amp 3

1.0 n

6

Amp 2

180 n

5

18 k

VCC2 33 V

4

Amp 1

Amp

3 In

Bias

10 k

Test

Logic

Fout Fref

VCC1

F1

5.0 V 9

10 k

(1) CA 13

15 k SCL 18

SDA

19

12

Gnd

D/A 3

6 Bit

Latches

D/A 2

6 Bit

Latches

D/A 1

6 Bit

Latches

Decoder

DTC

Shift Register

8 Bit

I2C Bus

Receiver

DTB

FUN

CL

Data

AD1

AD2 DTF

Latches

Shift Register

15 Bit

Latches A

Ref

Voltage

Latches

Phase

Comp

1.0 n

10 k

2

PHO

Fout

Fref

Ref

Divider

F1

62.5 kHz

4.0 MHz

1 XTAL

Osc

20 Gnd (2)

HF1 10

HF2 11

Preamp 1

÷8

Presc

Preamp 2

Latches B

Program Divider

15 Bit

TDI

Latch

Fout

Control

AVA

NOTES: 1. Pin 13: Short to VCC

Resistors ±10%

Open or 1.0 nF to Gnd

Short to Gnd

for addresses CC, CE

for addresses C8, CA (values 10 k and 15 k) for test only

for addresses C4, C6

for addresses C0, C2

2. The crystal may be connected to Pin 20 with no connection to external Gnd.

MOTOROLA ANALOG IC DEVICE DATA

7

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