MC44817D 查看數據表（PDF） - Motorola => Freescale

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MC44817D

TV AND VCR PLL TUNING CIRCUITS WITH 1.3 GHz PRESCALER AND 3–WIRE BUS

Motorola => Freescale 

MC44817/17B

Bit T6: Switches the Prescaler

T6 = 0

T6 = 1

Normal Operation, 1.3 GHz

Low Frequency Operation

Preamp. 2 Switched Off, 165 MHz maximum

The prescaler is bypassed and the power supply of

the prescaler is switched off. Input: 10 MHz

minimum, 20 mVrms minimum

Figure 4. Equivalent Circuit of the Integrated

Band Buffers

25 V

Protection

Gnd IB

ISUB

VCC3 12 V

(Min VCC1, Max 14.4 V)

0.15 V Typical

0.3 V Max

“On”/“Off”

(1)

NOTE: IB + ISUB = 8.0 mA Typical, 13 mA Max

IB = Base Current

ISUB = Substrate Current of PNP

Out

B0…B3

30 mA (40 mA

at 0 to 80°C)

The Programmable Divider

The programmable divider is a presettable down counter.

When it has counted to zero it takes its required division ratio

out of the latches B. Latches B are loaded from latches A by

means of signal TDI which is synchronous to the

programmable divider output signal.

Since latches A receive the data asynchronously with the

programmable divider; this double latch scheme is needed to

assure correct data transfer to the counter.

The division ratio definition is given by:

N = 16384 x N14 + 8132 x N13 + … + 4 x N2 + 2 x N1 + N0

Maximum Ratio 32767

(16363 in case of 18 bit bus protocol)

Minimum Ratio 17

N0 … N14 are the different bits for frequency information.

At power–on the whole bus receiver is reset and the

programmable divider is set to a counting ratio of N = 256 or

higher.

The Prescaler

The prescaler has a preamplifier which guarantees high

input sensitivity.

The Phase Comparator

The phase comparator is phase and frequency sensitive

and has very low output leakage current in the high

impedance state.

The Operational Amplifier

The operational amplifier is designed for very low noise,

low input bias current and high power supply rejection. The

positive input is biased internally. The operational amplifier

needs 28.5 V supply (VCC2) as minimum voltage for a

guaranteed maximum tuning voltage of 28 V.

Figure 6 shows a possible filter arrangement. The

component values depend very much on the application

(tuner characteristic, reference frequency, etc.).

The Oscillator

The oscillator uses a 3.2 to 4.0 MHz crystal tied to ground in

series with a capacitor. The crystal operates in the series

resonance mode.

The voltage at Pin 3 has low amplitude and low harmonic

distortion.

Figure 5. Equivalent Circuit of the Lock Output

VCC1 5.0 V

200 µA Typical

2.0 k

Lock

100 k 25 V Protection

Figure 6. Typical Tuner Application

IF

UHF

External Switching

VHF B III

13 12 11 10

14 12 V

Antenna

Filter

B. P. Filter

Mixer

5.0 V 7

B3 B2 B1 B0

T6

MC44817/17B

Bus

Rec

1.0 nF 8

÷8

Pres

Fosc

Program

Divider

VCC3

2

1

16

Osc & 3

Ref Div

Oscillator

VTUN

AGC

NOTES: 1. On some layouts the 100 Ω resistor will not be required.

2. C2 = 330 pF minimum is required for stability.

Gnd

9

330 p

(Note 2)

2.7 V

65

4

(Note 1)

47 k

47 nF

33 V

22 nF

Phase

Comp

15

Lock

CL

DA

EN

12 pF

3.2/4.0 MHz

MOTOROLA ANALOG IC DEVICE DATA

7

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