Datasheet

AD9880
Rev. 0 | Page 15 of 64
Power Management
The AD9880 uses the activity detect circuits, the active interface
bits in the serial bus, the active interface override bits, the
power-down bit, and the power-down pin to determine the
correct power state. There are four power states: full-power,
seek mode, auto power-down and power-down.
Table 7 summarizes how the AD9880 determines which power
mode to be in and which circuitry is powered on/off in each of
these modes. The power-down command has priority and then
the automatic circuitry. The power-down pin (Pin 81—polarity
set by Register 0x26[3]) can drive the chip into four power-
down options. Bits 2 and 1 of Register 0x26 control these four
options. Bit 0 controls whether the chip is powered down or the
outputs are placed in high impedance mode (with the exception
of SOG). Bits 7 to 4 of Register 0x26 control whether the
outputs, SOG, Sony Philips digital interface (SPDIF ) or I2S (IIS
or Inter IC sound bus) outputs are in high impedance mode or
not. See the 2-Wire Serial Control Register Detail section for
the details.
Table 7. Power-Down Mode Descriptions
Inputs
Mode Power-Down
1
Sync Detect
2
Auto PD Enable
3
Power-On or Comments
Full Power 1 1 X Everything
Seek Mode 1 0 0 Everything
Seek Mode 1 0 1
Serial bus, sync activity detect, SOG, band gap
reference
Power-Down 0 X
Serial bus, sync activity detect, SOG, band gap
reference
1
Power-down is controlled via Bit 0 in Serial Bus Register 0x26.
2
Sync detect is determined by OR’ing Bits 7 to 2 in Serial Bus Register 0x15.
3
Auto power-down is controlled via Bit 7 in Serial Bus Register 0x27
Table 8. Recommended VCO Range and Charge Pump Current Settings for Standard Display Formats
Standard Resolution Refresh Rate Horizontal Frequency Pixel Rate VCO Range
1
Current
VGA 640 × 480 60 Hz 31.5 kHz 25.175 MHz 00 101
72 Hz 37.7 kHz 31.500 MHz 01 011
75 Hz 37.5 kHz 31.500 MHz 01 100
85 Hz 43.3 kHz 36.000 MHz 01 100
SVGA 800 × 600 56 Hz 35.1 kHz 36.000 MHz 01 100
60 Hz 37.9 kHz 40.000 MHz 01 101
72 Hz 48.1 kHz 50.000 MHz 01 110
75 Hz 46.9 kHz 49.500 MHz 01 110
85 Hz 53.7 kHz 56.250 MHz 01 110
XGA 1024 × 768 60 Hz 48.4 kHz 65.000 MHz 10 011
70 Hz 56.5 kHz 75.000 MHz 10 100
75 Hz 60.0 kHz 78.750 MHz 10 100
80 Hz 64.0 kHz 85.500 MHz 10 101
85 Hz 68.3 kHz 94.500 MHz 10 110
SXGA 1280 × 1024 60 Hz 64.0 kHz 108.000 MHz 10 110
1280 × 1024 75 Hz 80.0 kHz 135.000 MHz 11 110
TV 480i 60 Hz 15.75 kHz 13.51 MHz 00 010
480p 60 Hz 31.47 kHz 27 MHz 00 101
720p 60 Hz 45 kHz 74.25 MHz 10 100
1035i 60 Hz 33.75 kHz 74.25 MHz 10 100
1080i 60 Hz 33.75 kHz 74.25 MHz 10 100
1080p 60 Hz 67.5 KHz 148.5 MHz 11 110
1
These are preliminary recommendations for the analog PLL and are subject to change without notice.