VSP9405B datasheet(9/126 Pages) MICRONAS

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DATA SHEET

VSP 94x2A

Micronas

Aug. 16, 2004; 6251-552-1DS

2.1.4. Synchronization

After elimination of the high frequent components of

the CVBS signal by a low pass filter, horizontal and

vertical sync pulses are separated. Horizontal sync

pulses are generated by a digital phase locked loop.

The time constant can be adjusted between fast and

slow behavior in four steps (PLLTC) to accommodate

different input sources (e.g. VCR). The time-constant

can be changed during normal operation without visi-

ble picture degradation. A fine tuning of the PLL time

constant can be done by NSRED.

Additional weak input signals from a satellite dish

(’fish’) become more stable when SATNR is enabled.

Vertical sync pulses are separated by integration of

equalizing pulses. A vertical flywheel mode improves

vertical sync separation for weak signals (VFLYWHL,

VFLYWHLMD

Additionally, v-syncs may be gated by VTHRL and

VTHRH

to reject invalid v-syncs (independently adjust-

able for 50 and 60 Hz sources) if no input signal is con-

nected the device switches to a freeruning mode. The

device can be configured to switch-on background

color when no or only a weak signal is applied (NOS-

IGB

). 50 Hz or 60 Hz operation for sync separation

may be forced separately or selected to work automat-

ically (FLNSTRD).

2.1.5. Chroma Decoder

The digital multistandard chroma decoder is able to

decode NTSC and PAL signals with a subcarrier fre-

quency of 3.58 MHz and 4.43 MHz (PAL B*/N/

60†,NTSC M/4.4) as well as SECAM signals with auto-

matic standard detection. Alternatively a standard can

be forced. The demodulation is done with a regener-

ated color-carrier. To enable a factory adjustment of

the crystal frequency, the frequency of the regenerated

subcarrier can be adjusted via SCADJ. For this pur-

pose the crystal deviation (SCDEV) can be read out

via I2C after chroma PLL locking (indicated by

SCOUTEN

) and can be stored in µC ROM for SCADJ.

For test purposes, CPLLOF allows the opening of the

chroma PLL loop.

For adjustment to the specific operational area an

automatic norm detection is selectable. Available

50 Hz color standards are PAL B, PAL N and SECAM.

Available 60 Hz color standards are NTSC M, PAL M,

PAL60 and NTSC44. For each line standard, one or

more color standards can be enabled for automatic

chroma standard detection. Please refer to

Table 2–

3: and Table 2–4: for allowed combinations.

The standard detection process can be set to slow or

fast behavior (LOCKSP). In slow behavior, 25 fields

are used to detect the standard, whereas 15 fields are

used in fast behavior.

If the detection was not success-

ful during this time frame, the system will switch to the

next enabled TV Standard.

Table 2–2: Clamping Adjustment

Signal

Description

CLMPST1

Measurement pulse start for ADC1

CLMPD1

Measurement pulse duration for ADC1

CLMPST1S

Clamping pulse start for ADC1

CLMPD1S

Clamping pulse duration for ADC1

CLMPST2

(Measurement pulse start for ADC2)

CLMPD2

(Measurement pulse duration for ADC2)

CLMPST2S

Measure and clamp start for RGBF-ADC (clamping start for ADC2)

CLMPD2S

Measure and clamp duration for RGBF-ADC (clamping duration for ADC2

* PAL B is representative for PAL B/G/H/I/N

† PAL60 and NTSC44 are nonstandard signals which

are generated by some VCR or DVD player

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