MC13081X View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

Manufacturer

MC13081X

Multimode Color Monitor Horizontal, Vertical, and Video Combination Processor

Motorola => Freescale 

MC13081X

Figure 10. Vertical Section

Free Running V–Ramp

1/4 V

3/4 V

Vert Sync Pulse

Vert Oscillator

9. Vertical Frequency Range (Pins 48, 51, 52)

The MC13081X vertical oscillator is an injection–lock

type. The device can handle vertical frequency from 45 Hz

to 100 Hz.

The internal ramp generator will generate a ramp output in

the absence of a V–Sync signal. Upon receiving an external

vertical sync pulse, the ramp up portion is forced to retrace,

and therefore, the vertical ramp output is synchronized with

incoming V–Sync.

The slope of the Vertical Ramp output is directly

proportional to the current flowing out of Pin 52. Half of this

current is used to charge up the Vertical Ramp Capacitor. As

the charging current is increased, so does the ramp slope.

External feedback can be provided from Pin 48 to Pins 51

and 52 for linearity adjustment.

10. Vertical Free Running Frequency (Pins 1, 2)

The purpose of the vertical oscillator is to maintain a

vertical ramp to the deflection circuitry in the event the

vertical sync is not present. Because of the injection–lock

type, the free running frequency must be lower than the

system’s lowest vertical frequency.

While various combinations of C4 and R9 can produce a

given frequency, it is recommended C4 be 0.1 µF in order to

obtain practical values for R9. The free running frequency

should be set at about 10% lower than the minimum

operating vertical frequency (54 Hz for a 60 Hz system).

R9 is then calculated from:

+ R9

VCC – 1.4

96 x C4 x FV

–

2.5 k

Connecting a potentiometer, (VR2) provides “Vertical

Hold” adjustment.

Vert Ramp Output

11. X–Ray Shutdown Protection (Pin 41)

The X–Ray input (Pin 41) permits shutting off the

horizontal drive, usually by external circuitry which monitors

faults within the high voltage supply, such as excess anode

current. This input is activated by taking it above ≈ 0.6 V

which causes the drive transistor at Pin 43 to be turned on

(low) permanently by an internal latch.

An external resistor must be connected to Pin 41 to limit

the input current, and to assist with the latching action (see

Figure 11). 10 kΩ is a typical value, but the value can be

chosen based on the specifies of the driving circuit. The

external resistor reduces the sensitivity of Pin 41 to noise and

transients which may otherwise result in false latches.

To resume normal operation (after correction of the fault),

lower Pin 41 below 0.4 V. If the external circuit’s normal

operation does not take it below 0.4 V, but does take it below

0.6 V, then recycle VCC “off”–“on”. If the pin is not used, it

must be connected to ground.

The minimum holding current to keep the latch on is

≈ 70 µA, while the minimum turn–on current is ≈ 0.4 µA.

Figure 11. X–Ray Shutdown Circuit

5.0 V

X–Ray

Shutdown

10 k 41

H–Drive

Shutdown

47 k

18

MOTOROLA ANALOG IC DEVICE DATA

Share Link: