DDP3310B datasheet(14/60 Pages) MICRONAS

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DDP 3310B

ADVANCE INFORMATION

Micronas

The picture tube measurement returns results on

every field for:

– cutoff R

– cutoff G

– cutoff B

– white-drive R or G or B (sequentially)

Thus, a cutoff control cycle for RGB requires one field

only while a complete white-drive control cycle

requires three fields. During cutoff and white-drive

measurement the average beam current limiter func-

tion (see Section 2.2.5.) is switched off. The amplitude

of the cutoff and white-drive measurement lines can be

programmed separately with IBRM and WDRM (see

Fig. 2–11). The start line for the tube measurement

(cutoff red) can be programmed via I2C-bus (TML).

The built-in control loop for cutoff and white-drive can

operate

three

different

modes

selected

CUT(WDR)_GAIN and CUT(WDR)_DIS.

– The user control mode is selected by setting

CUT(WDR)_GAIN = 0. In this mode the registers

CUT(WDR)_R/G/B are used as direct control values

for cutoff and drive using the whole 9-bit range. If

the

measurement

lines

are

enabled

(CUT(WDR)_DIS = 0) the user can read the mea-

sured cutoff & white drive values in the CUT-

OFF(WDRIVE)_R/G/B registers. An external soft-

ware

can

now

control

the

settings

the

CUT(WDR)_R/G/B registers.

– The

automatic

mode

selected

setting

CUT(WDR)_GAIN > 0 and CUT(WDR)_DIS = 0. In

this mode, the registers CUT(WDR)_R/G/B are

used as reference for the measured values (CUT-

OFF(WDRIVE)_R/G/B). Due to the 8-bit resolution

of the ADC, only 8 LSB can be used as reference

values. The calculated error is used with a small

hysteresis (1,5 %) to adjust cutoff and drive. The

higher the loop gain

(CUT(WDR)_GAIN), the

smaller the time constant for the adjustment.

– If

the

automatic

mode

was

once

enabled

(CUT(WDR)_GAIN > 0), the control loop can be

stopped by setting CUT(WDR)_DIS = 1. In this

mode, the calculated cutoff and drive values will no

longer be modified and the measurement lines are

suppressed. Changes of the reference values

(CUT(WDR)_R/G/B) have no effect.

If one of the calculated red, green, or blue white-drive

values exceeds its maximal possible value (WDR_R/

G/B>511), the white balance gets misadjusted. An

automatic drive saturation avoidance prevents from

this effect (WDR_SAT = 1) from occurring. If one drive

value

exceeds

the

maximum

allowed

threshold

(MAX_WDR), the amplitude of the white-drive mea-

surement line will be increased and decreased if one

of them goes below the fixed threshold 475.

Fig. 2–11: MADC measurement timing

Ultra Black

Black

Cutoff

White-

Drive

CUT_R + IBRM

CUT_R + IBRM + WDRM

×WDR_R

TML

CUT_G + IBRM

CUT_B + IBRM

CUTOFF

Active

Resistors

R1||R2||R3

R1||R3

Cutoff

R1||R2||R3

VBST

Lines

Measurement

VBSO

WDR

OFFSET

BCL

ROUT

GOUT

BOUT

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