LM9832 datasheet(28/42 Pages) NSC

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• To prevent sensor saturation, the LM9832 is always clocking

the CCD/CIS, except when it is in Reset or Standby (Register 7

bit 2 or 3 = 1).

• There is a bit for Fake Optical Black Pixels (register 19, bit 2).

This is used with Dyna CIS sensors. In this mode, the RS out-

put pulses once inside the TR1 pulse, then is held high until the

end of the optical black pixels. The TR1 pulse is extended until

the trailing edge of the first RS pulse. This mode works for TR1

only, under all TR1 settings (normal and CIS TR1 Timing

modes 1 and 2).

5.3 AFE Operation

The LM9832 supports the following operation modes, controlled

by registers 26 and 27:

• 3 Channel Pixel Rate Mode. In this mode all three channels are

converted with the multiplexer in front of the ADC switching at

the ADC conversion rate, producing interleaved RGB data that

is transferred to RAM. The ADC runs at MCLK/8, each chan-

nel’s pixel rate is MCLK/24. Each color has its own offset and

gain coefficients. This mode typically uses Illumination Mode 1.

• 3 Channel Line Rate Mode. In this mode all three channels are

converted with the multiplexer in front of the ADC switching at

the line rate, producing a line of Red data, followed by a line of

Green data, followed by a line of Blue data, etc. that is trans-

ferred to RAM. The selected channel and the ADC both run at

MCLK/8. Each color has its own offset and gain coefficients.

This mode typically uses Illumination Mode 1.

In the 3 Channel Line Rate Mode three TR pulses are generated.

TRRED is the TR1 output, TRGREEN is the TR2 output, and

TRBLUE is the CP2 output. In this mode TR pulses for a particular

color can be “skipped”, increasing the integration time for that

color. In the example shown in Figure 30, the red channel sees 2

times the integration time of the green channel, and the blue

channel sees 3 times the integration time of the green channel.

Each channel can be independently programmed to drop 0, 1, or

2 TR pulses.

Each color’s TR pulse can be programmed to occur in position 1

(inside Ø1 high) or position 2 (inside Ø1 low), as shown in Figure

31.

• 1 Channel Grayscale: Uses the selected channel’s offset and

gain coefficients for all lines. 1 Channel Grayscale is used to

scan a grayscale images. This mode typically uses Illumination

Mode 1 when used with a 3 Channel Color sensor, or Illumina-

tion Mode 3 when used with a 1 Channel sensor.

ø1 inside TR1 pulse

TR1

ø1

tø1/4

tø1

Figure 26: CIS TR1 Timing Mode 2

Figure 27: Fake Optical Black Pixels

Trailing edge of

first RS pulse

End of Optical

Black Pixels

TR1

Red Channel

Figure 28: 3 Channel Pixel Rate Mode

Green Channel

Blue Channel

ADC

ADC Out LIne 1: RGBRGBRGBRGBRGB...

ADC Out LIne 2: RGBRGBRGBRGBRGB...

ADC Out LIne 3: RGBRGBRGBRGBRGB...

ADC Out LIne 4: RGBRGBRGBRGBRGB...

Pixel-Rate

Multiplexing

Red Channel

Figure 29: 3 Channel Line Rate Mode

Green Channel

Blue Channel

ADC

ADC Out LIne 1: RRRRRRRRRRRRRRR...

ADC Out LIne 2: GGGGGGGGGGGGGG...

ADC Out LIne 3: BBBBBBBBBBBBBBBBB...

ADC Out LIne 4: RRRRRRRRRRRRRRR...

Line-Rate

Multiplexing

Figure 30: 3 Channel Line Rate TR Pulse Timing

TRRED

TRGREEN

TRBLUE

Multiplexer

Channel

Red

Green

Blue

Red

Green

tINT (RED)

tINT (GREEN)

tINT (BLUE)

TRRED

TRGREEN

TRBLUE

Ø1

Figure 31: 3 Channel Line Rate Mode with 2 TR

Pulse Positions

Applications Information (Continued)

LM9832 Datasheet(PDF) 28 Page - National Semiconductor (TI)

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