TDA4882 데이터 시트보기 (PDF) - Philips Electronics

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TDA4882

Advanced monitor video controller for OSD

Philips Electronics 

Philips Semiconductors

Advanced monitor video controller for OSD

Product specification

TDA4882

6 PINNING

SYMBOL

BC

VIN1

GC1

GND

VIN2

CC

VP

VIN3

HBL

CL

GC3

FB3

VOUT3

IOUT3

FB2

VOUT2

IOUT2

FB1

VOUT1

IOUT1

PIN

DESCRIPTION

1 brightness control

2 signal input channel 1

3 gain control channel 1

4 ground

5 signal input channel 2

6 contrast control, OSD switch

7 supply voltage

8 signal input channel 3

9 horizontal blanking, switch-off

10 input clamping, vertical blanking,

test mode

11 gain control channel 3

12 feedback channel 3

13 voltage output channel 3

14 current output channel 3

15 feedback channel 2

16 voltage output channel 2

17 current output channel 2

18 feedback channel 1

19 voltage output channel 1

20 current output channel 1

handbook, halfpage

BC 1

VIN1 2

20 IOUT1

19 VOUT1

GC1 3

18 FB1

GND 4

17 IOUT2

VIN2 5

CC 6

16 VOUT2

TDA4882

15 FB2

VP 7

VIN3 8

14 IOUT3

13 VOUT3

HBL 9

12 FB3

CL 10

11 GC3

MHA815

Fig.2 Pin configuration.

7 FUNCTIONAL DESCRIPTION

7.1 General

Figure 4 illustrates the signal processing. The RGB input

signals 0.7 V (p-p) are capacitively coupled into the

TDA4882 from a low ohmic source and are clamped to an

internal DC voltage (artificial black level). Composite

signals will not disturb normal operations because an

internal clipping circuit cuts all signal parts below black

level. Channels 1 and 3 have a maximum total voltage

gain of 7 dB (maximum contrast and maximum individual

channel gain), channel 2 having 4.4 dB (maximum

contrast and nominal gain). With the nominal channel gain

of 1 dB and nominal contrast setting the nominal

black-to-white output signal is 0.79 V (p-p). Brightness,

contrast and gain control is by DC voltage.

7.2 Brightness control

Brightness control (Fig.4) yields a simultaneous signal

black-level shift of the three channels relative to a

reference black level.

For nominal brightness (pin 1 open-circuit) the signal black

level is equal to the reference black level.

7.3 Contrast control

Contrast is voltage controlled to affect the three channels

simultaneously (Fig.4). To provide the correct white point,

individual gain controls adjust the signals of channels 1

and 3 relative to the reference channel 2. Gain setting also

changes contrast to achieve correct grey scale tracking.

7.4 Output stages

The output stages provide both voltage and current

outputs. External cascode transistors reduce power

consumption of the IC and prevent breakdown of the

output transistors. Signal output currents and peaking

characteristics are determined by external components at

the voltage outputs and the video supply. The channels

have separate internal feedback loops which ensure large

signal linearity and marginal signal distortion irrespective

of output transistor thermal VBE variation (Fig.8).

1997 Sep 04

5

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