I
NTEGRATED
C
IRCUITS
D
IVISION
UG-CPC590x_EvalBd-R00A
PRELIMINARY
1
The CPC5902G/5903G Evaluation Board can be used
to isolate an I
2
C bus, and to evaluate the performance
obtainable when communicating between the user's
I
2
C devices. The 8-pin DIP socket can be populated
with either a CPC5902G (for both SCL and SDA
bidirectional) or with a CPC5903G (for SDA
bidirectional, SCL sideA to sideB only).
At the left side of the board are four 0.1 inch centered
posts that carry VDDA, GNDA, SCLA and SDAA. See
the drawing above for signal, component, and jumper
locations. Best performance will result if the VDDA and
GNDA posts are connected to the same VDD and
GND as the sideA I
2
C bus master. The SCLA post
should be connected to the I
2
C serial clock line SCL at
the bus master on sideA. In addition, the SDAA post
should be connected to the I
2
C serial data line at the
bus master. On the right side of the board there are
four posts which carry VDDB, GNDB, SCLB and
SDAB when connected to the sideB I
2
C devices.
At the top left of the board are duplicate posts, which
are electrically shorted to the VDDA and GNDA posts
on the left side of the board. These two posts enable
convenient operation in standalone mode, when a full
I
2
C bus may not be available at sideA. Similarly, at the
top right of the board, there are duplicates of the
VDDB and GNDB posts. The CPC5902G and
CPC5903G will each operate correctly for
2.7V < VDDA < 5.5V and 2.7V < VDDB < 5.5V.
While it is possible to attach a second lab power
supply to VDDA, which is not identical to the supply at
the bus master on sideA, and to operate the board
with a live I
2
C interface, this is not the recommended
mode of operation. The same is true for connecting a
second, non-identical lab power supply to VDDB. The
V
IL
and V
IH
voltages at the bus isolator are derived
from the VDDA and VDDB voltages. Thus, the
switching thresholds will differ, and noise rejection of
the bus will be worse if the voltage at VDDA is not
identical to the voltage at the VDD connected to the
devices as well as any pull-up resistors on the rest of
the sideA bus segment. Similarly, VDDB should be the
same voltage used at the devices and any pull-ups on
the sideB bus. If either of VDDA or VDDB is not the
04-26-12
CPC5902/3-EVAL. PCB
R4
R3
C3
JP3
JP4
JP1
JP2
JP9
VDDA
GNDA
SCLA
SDAA
VDDB
GNDB
SCLB
SDAB
CPC5902
/
3
VDDA
GNDA
GNDB
R2
R1
C1
R8
R7
JP7
JP8
C6
JP5
JP6
C4
R6
R5
JP10
VDDB
1001
1001
1001
1001
1501
2701
1501
2701
CPC5902G/CPC5903G
Evaluation Board
User’s Guide