MC44140DW Ver la hoja de datos (PDF) - Motorola => Freescale

Número de pieza

componentes Descripción

Fabricante

MC44140DW

Chroma Delay Line HCMOS

Motorola => Freescale 

vided during the whole line blanking period to allow the

MC440XX to clamp the signals on the other end of the exter-

nal output coupling capacitors.

Differential Clock Input

Pins 1 and 16 form a differential clock input of high sensi-

tivity and good noise rejection. Pin 16 is an ac ground of the

differential input and must be decoupled to ground.

APPLICATION CIRCUIT

A schematic diagram of the MC44140 application circuit is

shown in Figure 5. All of the inputs/outputs shown on the left

of the diagram have the MC44000 as their destination. The

17.7 MHz and 14.3 MHz crystals shown in fact form part of

the MC44000 circuit; this device controls the crystal selection

and applies the drive to it. The majority of the rest of the cir-

cuit consists of coupling capacitors for the signal inputs and

outputs, whose function for black level clamping has already

been described. A pull–up resistor is connected to pin 16 for

the purpose of providing a bias current, which the IC uses to

set the dc operating point of internal operational amplifiers.

Separate power supply pins (VDD and VSS) are provided to

each of the analog section and the digital section of the chip.

Both of the + 5 V supply pins are filtered using a series resistor

and small ceramic and electrolytic capacitors mounted close

by each supply pin and its adjacent ground pin. The supplies,

especially the analog pin, should be very well bypassed in or-

der to avoid noise interfering with the clock input (pin 1),

whose input level is only some 50 mVp–p.

MOTOROLA

MC44140

2–7

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