Datasheet

PCA9527_1 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 01 — 29 June 2009 9 of 22
NXP Semiconductors
PCA9527
3-channel bidirectional bus extender for HDMI, I
2
C-bus and SMBus
According to Figure 5, when port A of the PCA9527 is pulled LOW by a driver on the
I
2
C-bus, a comparator detects the falling edge when it goes below 0.3V
CC(A)
and causes
the internal driver on port B to turn on, causing port B to pull down to about 0.5 V. When
port B of the PCA9527 falls, first a CMOS hysteresis type input detects the falling edge
and causes the internal driver on port A to turn on and pull the port A pin down to ground.
In order to illustrate what would be seen in a typical application, refer to Figure 11 and
Figure 12.
If the bus master in Figure 5 were to write to the slave through the PCA9527, waveforms
shown in Figure 11 would be observed on the A bus. This looks like a normal I
2
C-bus
transmission except that the HIGH level may be as low as 2.7 V, and the turn on and turn
off of the acknowledge signals are slightly delayed.
The master drives the B bus to ground or lets it float to V
CC(B)
as it sends data to the slave
at the falling edge of the 8
th
clock, master releases SDAB on the B bus and slave pulls
SDAA on the A bus to ground, causing the PCA9527 to pull SDAB on the B bus to 0.5 V.
At the falling edge of the 9
th
clock, the master again drives the B bus and slave releases
the A bus.
Multiple PCA9527 port A sides can be connected in a star configuration (Figure 8),
allowing all nodes to communicate with each other.
Multiple PCA9527s can be connected in series (Figure 9) as long as port A is connected
to port B. I
2
C-bus slave devices can be connected to any of the bus segments. The
number of devices that can be connected in series is limited by repeater
delay/time-of-flight considerations on the maximum bus speed requirements.
Fig 7. Sink or LCD TV application
002aad973
V
CC(A)
V
CC(B)
SDAB SDAA
SCLB SCLA
10 kΩ
(optional)
GND
10 kΩ
CECB
3.3 V
0.1 µF
10 kΩ
HDMI
RECEIVER
PCA9527
0.1 µF
47 kΩ
5 V
HDMI cable
DDC line
DVD (source)
PCA9507
PCA9512A
PCA9515
PCA9517
PCA9527
LCD TV
22 Ω
22 Ω
EN
10 kΩ
CECA
10 kΩ