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Table 7-12, Crt interface signals, Table 7-13 – AMD Geode LX [email protected] User Manual

Page 612: Crt display recommended operating conditions

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612

AMD Geode™ LX Processors Data Book

Electrical Specifications

33234H

Table 7-12. CRT Interface Signals

Symbol

Parameter

Min

Max

Unit

Comments

t

CK

DOTCLK Period

2.8

ns

350 MHz

t

CH

DOTCLK High time

1.2

ns

45% t

CK

t

CL

DOTCLK Low time

1.2

ns

45% t

CK

DOTCLK long term output jitter

15%

t

CK

Note

1

t

SKEW

Skew between RED, GREEN, BLUE Output Valid

0

0.6

ns

Between any
two signals

Note 2

Note 1. Measured as per VESA requirements. The jitter is observed at its worst case point on a scan line after HSYNC

triggers up to and including the next HSYNC trigger.

Note 2. HSYNC and VSYNC for CRT timing are generated from the same on-chip clock that is used to generate the RED,

GREEN, and BLUE signals.

Table 7-13. CRT Display Recommended Operating Conditions

Symbol

Parameter

Min

Typ

Max

Units

Comments

V

DAC

Power Supply connected to
DAV

DD

3.14

3.3

3.46

V

R

L

Output Load RED, GREEN and
BLUE

37.5

Note 1

Ω

One each signal.

I

OUT

Output Current RED, GREEN
and BLUE

21

mA

One each signal.

R

SET

Value of the full-scale adjust
resistor connected to DRSET

1.2K

Ω

This resistor should have a
1% tolerance.

VEXT

REF

External voltage reference con-
nected to the DVREF pin

1.235

V

Note 1. There is a 75

Ω resistor on the motherboard and a 75 Ω resistor in the CRT monitor to create the effective 37.5 Ω

typical resistance.

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