Datasheet
REV. 0
–16–
AD9887
Table V. VCO Frequency Ranges
Pixel Clock K
VCO
Gain
PV1 PV0 Range (MHz) (MHz/V)
0 0 12–35 150
0 1 35–70 150
1 0 70–110 150
1 1 110–140 180
Table VI. Charge Pump Current/Control Bits
Ip2 Ip1 Ip0 Current (A)
00050
0 0 1 100
0 1 0 150
0 1 1 250
1 0 0 350
1 0 1 500
1 1 0 750
1 1 1 1500
3. The 3-Bit Charge Pump Current Register. This register
allows the current that drives the low pass loop filter to be
varied. The possible current values are listed in Table VI.
provides 32 phase-shift steps of 11.25° each. The Hsync
signal with an identical phase shift is available through the
HSOUT pin. Phase adjustment is still available if the pixel
clock is being provided externally.
4. The 5-Bit Phase Adjust Register. The phase of the generated
sampling clock may be shifted to locate an optimum sam-
pling point within a clock cycle. The Phase Adjust register
The COAST allows the PLL to continue to run at the same
frequency, in the absence of the incoming Hsync signal. This
may be used during the vertical sync period, or any other
time that the Hsync signal is unavailable. The polarity of
the COAST signal may be set through the Coast Polarity Bit.
Also, the polarity of the Hsync signal may be set through the
HSYNC polarity Bit. If not using automatic polarity
detection, the HSYNC and COAST polarity bits should
be set to match the Polarity of their respective signals.
Table VII. Recommended VCO Range and Charge Pump Current Settings for Standard Display Formats
Horizontal
Refresh Frequency Pixel Rate
Standard Resolution Rate (Hz) (kHz) (MHz) VCORNGE CURRENT
VGA 640 × 480 60 31.5 25.175 00 101
72 37.7 31.500 00 101
75 37.5 31.500 00 110
85 43.3 36.000 00 110
SVGA 800 × 600 56 35.1 36.000 00 101
60 37.9 40.000 01 101
72 48.1 50.000 01 101
75 46.9 49.500 01 101
85 53.7 56.250 01 110
XGA 1024 × 768 60 48.4 65.000 01 110
70 56.5 75.000 10 101
75 60.0 78.750 10 101
80 64.0 85.500 10 101
85 68.3 94.500 10 101
SXGA 1280 × 1024 60 64.0 108.000 10 110
75 80.0 135.000 11 110
85 91.1 157.500* 10 110
UXGA 1600 × 1200 60 75.0 162.000* 10 110
65 81.3 175.500* 10 110
70 87.5 189.000* 10 110
75 93.8 202.500* 10 110
85 106.3 229.500* 11 110
*Graphics sampled at one-half the incoming pixel rate using Alternate Pixel Sampling mode.
OBSOLETE