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System Implementation
1-14
1.3.1 P
2
C Interface for TPS22X6 Power Switch
The interface between the PCI445X device and TPS22X6 power switch is
serialized to reduce the number of signal lines. The P
2
C interface requires only
three lines to control the switch. As a PCI445X default, the CLOCK signal is
selected from an external source. It is usually provided from RTC, 32.768 kHz.
The PCI445X device can also generate this clock from an internal ring
oscillator. The typical frequency of the internal ring oscillator is 16 kHz. If using
the internal clock source, then a pulldown resistor is required on the CLOCK
terminal. If arranging for D3 wake implementation, then connect the power
switch RESET
terminal to GRST.
Figure 1–4. TPS22X6 Power Switch Interface
Pulldown on
CLOCK
V
CCA
V
CCB
V
PPB
V
CCA
V
PPA
DATA
CLOCK
PCI445X
V
CCB
SLOT
A
SLOT
B
LATCH
TPS22X6
1.3.2 Zoomed Video (ZV) Interface
The PCI445X device has an internally buffered and selectable ZV interface.
It supports three ZV sources, two from PC Cards and one from an external
source. An auto ZV detect function provides software independent ZV
switching. The auto ZV detect function senses the pixel clocks, arbitrates three
inputs, and selects one of them according to priority bits.
Figure 1–5. Example of a ZV Interface
23
SLOT
B
SLOT
A
PCI445X
Buffer
3rd ZV
Source
ZVSTATZVPCLK
Sound
Controller
Stereo
Audio
Codec
Graphic
Controller
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