845GL datasheet(154/193 Pages) INTEL

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Electrical Characteristics

154

Intel® 82845G/82845GL/82845GV GMCH Datasheet

6.6.2

DAC Reference and Output Specifications

NOTES:

1. VESA Video Signal Standard

2. Complement DAC channel output termination resistors are only required for differential video routing to the

VGA connector.

3. Video filter capacitors and ferrite bead arranged in a PI configuration (one PI filter for RED, GREEN, BLUE

outputs)

6.6.3

DAC AC Characteristics

NOTES:

1. Measured at each RED, GREEN, BLUE termination according to the VESA Test Procedure – Evaluation of

Analog Display Graphics Subsystems Proposal (Version 1, Draft 4, December 1, 2000)

2. R,G,B Max Video Rise/Fall Time: 50% of minimum pixel clock period

3. R,G,B Min Video Rise/Fall Time: 20% of minimum pixel clock period

4. Max settling time: 30% of minimum pixel clock period

5. Video channel-channel output skew: 25% of minimum pixel clock period

6. Overshoot/undershoot: ± 12% of black-white video level (full-scale) step function

7. Noise injection ratio: 0.5% of maximum luminance voltage (dc to max. pixel frequency)

Table 6-8. DAC Reference and Output Specifications

Parameter

Min

Typical

Max

Units

Notes

Reference resistor

137

Ω

1% tolerance, 1/16 W

RED, GREEN, BLUE

termination resistor

Ω

Note 1, 1% tolerance, 1/16 W

RED#,GREEN#,BLUE#

termination resistor

37.5

Ω

Note 2, 1% tolerance, 1/16 W

(applies to differential routing)

Video Filter Ferrite Bead

Ω

Note 3, @ 100 MHz, (each RED,

GREEN, BLUE output)

Video Filter Capacitors

3.3

Note 3, two capacitors per RED,

GREEN, BLUE output

Table 6-9. DAC AC Characteristics

Parameter

Min

Typical

Max

Units

Notes

Pixel Clock Frequency

350

MHz

RED, GREEN, BLUE Video

Rise Time

0.57

1.43

Notes 1, 2, (10–90% of black-to-

white transition, at 350 MHz pixel

clock)

RED, GREEN, BLUE Video

Fall Time

0.57

1.43

Notes 1, 3, (90–10% of white-to-

black transition, at 350 MHz pixel

clock)

Settling Time

0.86

Notes 1, 4, at 350 MHz pixel clock

Video channel-to-channel

output skew

0.714

Notes 1, 5, at 350 MHz pixel clock

Overshoot/ Undershoot

-0.084

+0.084

Notes 1, 6, Full-scale voltage step

of 0.7 V

Noise Injection Ratio

0.5

Notes 1, 7

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