MC44827BDTB データシートの表示（PDF） - Motorola => Freescale

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MC44827BDTB

Low Power PLL Tuning Circuits for 3-Wire Bus

Motorola => Freescale 

MC44827/27B

Figure 7. Equivalent Circuit of the Lock Output

VCC1 5.0 V

200 µA Typical

2.0 k

Lock

“On”/“Off”

100 k 25 V Protection

5.0 k

“Off”/“On”

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 8 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 or a 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.

Power Dissipation

The typical power dissipation of the circuit is about

200 mW (VTUN = 15 V with internal pull–up of 60 kΩ, one

buffer “On” at 30 mA). It is calculated with the following

formula:

+ ǒ Ǔ ) PD

VCC1 x ICC1

VCC2 – VTUN

60 kΩ

x

VCC2

) ǒ Ǔ ) ǒ Ǔ VCC3 x ICC3

Vsat(buffer) x Iout(buffer)

) ) Example: (5 x 23)

32 – 15

60

x 32

(12 x 6.5)

) + (0.15 x 30) 206.5

Figure 8. 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

MC44827/27B

Bus

Rec

1.0 nF 8

÷8

Pres

Fosc

Program

Divider

VCC3

2

1

16

Osc & 3

Ref Div

Oscillator

VTUN

AGC

NOTE: 1. 330 pF minimum is required for stability.

Gnd

9

Vref

65

4

330 p

(Note 1)

33 V

120 k

18 nF

8.2 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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