82845PE Datasheet, PDF (149/176 Pages) Intel Corporation – 82845GE Graphics and Memory Controller Hub (GMCH) and 82845PE Memory Controller Hub (MCH)

Electrical Characteristics
6.6
6.6.1
DAC Characteristics (Intel^® 82845GE only)
The GMCH DAC (digital-to-analog converter) consists of three identical 8-bit DACs to provide
red, green, and blue color components. Each DAC can output a current from 0 to 255 units of
current, where one unit of current (LSB) is defined based on the VESA video signal standard.
DAC DC Characteristics
Table 6-7. DAC DC Characteristics: Functional Operating Range (VCCDAC = 1.5 V ± 5%)
(Intel^® 82845GE only)
Parameter
Min Typical Max Units
Notes
DAC Resolution
Max Luminance (full-scale)
Min Luminance
LSB Current
Integral Linearity (INL)
Differential Linearity (DNL)
Video channel-channel voltage
amplitude mismatch
Monotonicity
8
0.665
0.700
0.770
0.000
73.2
–1.0
+1.0
–1.0
+1.0
6
Guaranteed
Bits Note 1
V
Notes 1, 2, 4, white video level
voltage
V
Notes 1, 3, 4, black video level
voltage
µA Notes 4, 5
LSB Notes 1, 6
LSB Notes 1, 6
% Notes 7
NOTES:
1. Measured at each R,G,B termination according to the VESA Test Procedure – Evaluation of Analog Display
Graphics Subsystems Proposal (Version 1, Draft 4, December 1, 2000)
2. Max steady-state amplitude
3. Min steady-state amplitude
4. Defined for a double 75 Ω termination
5. Set by external reference resistor value
6. INL and DNL measured & calculated according to VESA Video Signal Standards
7. Max full-scale voltage difference among R,G,B outputs (percentage of steady-state full-scale voltage)
6.6.2 DAC Reference and Output Specifications
Table 6-8. DAC Reference and Output Specifications (Intel^® 82845GE only)
Parameter
Min Typical Max Units
Notes
Reference resistor
137
R,G,B termination resistor
75
R#,G#,B# termination resistor
37.5
Video Filter Ferrite Bead
75
Video Filter Capacitors
3.3
Ω
1% tolerance, 1/16 W
Ω
Note 1, 1% tolerance, 1/16 W
Ω
Note 2, 1% tolerance, 1/16 W
(applies to differential routing)
Ω
Note 3, @ 100 MHz, (each R,G,B
output)
pF
Note 3, two capacitors per R,G,B
output
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 R,G,B outputs)
Intel^® 82845GE/82845PE Datasheet
149