KB2511B データシートの表示（PDF） - Samsung

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KB2511B

DEFLECTION PROCESSOR FOR MULTISYNC MONITORS

Samsung 

KB2511B

DEFLECTION PROCESSOR FOR MULTISYNC MONITORS

free running frequency(fo) adjustment.

Sending the desired fo on the sync input and progressively decreasing the free running frequently I2C register

value(address 02), the HLOCKOUT Pin will go high as soon as the proper setting is reached. Setting the free run-

ning frequency this way allows to fully exploit the KB2511B horizontal frequency range.

HORIZONTAL PART

Internal input conditions

Horizontal part is internally fed by synchro processor with a digital signal corresponding to horizontal synchro

pulses or to TTL composite input.

concerning the duty cycle of the input signal, the following signals (positive or negative)may be applied to the

circuit.

Using internal integration, both signals are recognized on condition that Z/T < 25%, synchronisation occurs on the

leading edge of the internal sync signal. The minimum value of Z is 0.7µs.

Z

T

Z

Figure 6.

An other integration is able to extract vertical pulse of composite synchro if duty cycle is more than 25% (typically

d = 35%) (7)

c

d

d

TRAMEXT

Figure 7.

The last feature performed is the equalizing pulses removing to avoid parasitic pulse on phase comparator input

which is intolerent to wrong or missing pulse.

PLL1

The PLL1 is composed of a phase comparator, an external filter and a voltage control oscillator (VCO).

The phase comparator is a phase frequency type designed in CMOS technology. This kind of phase detector

avoids locking on false frequencies. It is followed by a charge pump, composed of two current sources sunk and

sourced (I = 1mA typ. when locked, I = 140mA when unlocked). This difference between lock/unlock permits a

smooth catching of horizontal frequency by PLL1. This effect is reinforced by an internal original slow down system

when PLL1 is locked avoiding horizontal too fast frequency change.

The dynamic bahaviour of the PLL is fixed by an external filter which integrates the current of the charge pump.

A CRC filter is generally used (see figure 8 )

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