MC13081X データシートの表示（PDF） - Motorola => Freescale

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MC13081X

Multimode Color Monitor Horizontal, Vertical, and Video Combination Processor

Motorola => Freescale 

MC13081X

The following describes a step–by–step procedure in

using the MC13801 for a typical multisync color monitor

chassis; component notations refer to Figure 2.

1. Horizontal Frequency Range Resistor

Network (Pins 11, 12)

FHm = Minimum Horizontal Frequency

FHx = Maximum Horizontal Frequency

Oscillator Transfer Constant = 122 Hz/µA

+ R5

6.35 x 108

FHx – FHm

+ R6

5

FHx

122 x 106

–

3.5

R5

v t R4

VCC – 6.0

1.5

x

R5

and

VCC – 1.5

R4

1.0 mA

For most applications, R4 = R5 provides the

required results.

NOTE: In order to compensate device/component tolerance, a

potentiometer is recommended in series with R6, as VR1.

2. Horizontal Frequency Range Phase Detector Filter

Network (Pin 10)

Typical values are:

C10 = 1.0 nF

C11 = 100 nF

R15 = 5.6 k

C11 ≥ 100 x C10

NOTE: C10 and C11 should have less than 1.0 µA leakage.

3. Horizontal Free Running Frequency

The voltage at Pin 10 will be buffered to Pin 11, and

hence control the internal oscillator. In the absence of

horizontal sync signal, the free running horizontal frequency

will vary between preset minimum and maximum horizontal

frequency values.

If an undetermined free running frequency value is not

desired, a large impedance resistor can be used to pull

Pin 10 to VCC or Gnd, and the free running frequency will be

equal to FHm or FHx, respectively.

The free running frequency can also be set to any value

within the horizontal frequency range by using a voltage

divider, as R7 and R8 indicate.

+ ) V11

VD

x

R7

R7 R8

+ ) I12

V11

R6 VR1

–

V11 –

5

5

+ Free Running Frequency

I12

µA

x

122 Hz

µA

The above formula provides the ratio of R7 and R8. The

values chosen should be similar to those shown in Figure 2.

4. Horizontal Flyback Input (Pin 46)

The horizontal flyback signal not only provides proper

timing reference for the horizontal drive output, but also

supplies the necessary blanking for the video outputs.

There are two precautions for the flyback input. First, the

signal should have a zero volt reference, and second, the

peak value should be as near to VCC as possible.

The threshold voltage for Pin 46 is 0.7 V. The blanking

period depends on the amplitude, as shown in Figure 3 (X and

Y, respectively). A larger amplitude provides better

consistency and control of the blanking period.

Figure 3. Voltage for Flyback

X

Y

0.7 V

5. Frequency Switch (Pin 14 to 17)

There are two frequency switches available for screen

size compensation for different timing standards. Each

switch will turn on at the switch frequency set with its external

resistor. See Figure 4.

Figure 4. FH Switches

VCC

15, 17

Ra

I12

2

1.0 k

3.0 k

5.0 V

Rb

The switch frequency is calculated as follow:

+ + ) SF

Switch Frequency

SF

5 x 2 x 122 x 106

Ra Rb

In considering the ratio of Ra to Rb, the following

parameters, and their tolerances, need to be clarified:

1. Iosc

2. 5.0 Vref

3. Vhys

4. Ra, Rb

±10%

±5%

±5%

±?%

Internally, the lock–in horizontal frequency will build up a

current reference, and half of this current reference is used

for setting up a voltage and then compared with the internal

5.0 Vref. Looking at the four parameters above, the first three

are IC related, while the last item depends on the external

component tolerance.

By adding up the first three items, the value of Ra and Rb

should be chosen to compensate for about 20% of system

tolerance.

Therefore, if Ra is chosen to be 70% of the calculated

value (Ra + Rb), Rb should be 60% of (Ra + Rb). That

12

MOTOROLA ANALOG IC DEVICE DATA

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