ISL58327 Datasheet, PDF (13/15 Pages) Intersil Corporation – Wide Optical Spectrum Laser Power Monitor IC

ISL58327
Serial Interface Protocol
I²C DATA ^START
DEVICE ADDRESS W A REGISTER ADDRESS
STOP START DEVICE ADDRESS
A
DATA BYTE0
I²C SDA
IN
I²C SDA
OUT
A6 A5 A4 A3 A2 A1 A0 W A R7 R6 R5 R4 R3 R2 R1 R0 A
SDA DRIVEN BY MASTER
A SDA DRIVEN BY MASTER A
A6 A5 A4 A3 A2 A1 A0 W A
SDA DRIVEN BY ISL58327
SDA DRIVEN BY MASTER
A D7 D6 D5 D4 D3 D2 D1 D0
I²C CLK
12 3456 789123456 789
123 45 67 89123456789
FIGURE 4. I²C READ TIMING DIAGRAM SAMPLE
I²C DATA
I²C SDA IN
I²C SDA OUT
I²C CLK IN
START
DEVICE ADDRESS
WA
REGISTER ADDRESS
A
FUNCTIONS
A STOP
A6 A5 A4 A3 A2 A1 A0 W A R7 R6 R5 R4 R3 R2 R1 R0 A B7 B6 B5 B4 B3 B2 B1 B0 A
SDA DRIVEN BY MASTER
A
SDA DRIVEN BY MASTER
A
SDA DRIVEN BY MASTER
A
1 2 34 5 67 8 9 1 2 34 56 7 8 9 12 3 45 67 89
FIGURE 5. I²C WRITE TIMING DIAGRAM SAMPLE
I²C Interface
The device address of the I²C bus of the ISL58327 is a
7 bits fixed address 0011_10(A0)xb, where (A0) can be hard
wired. Note that (A0) is internally pulled down. When
001110(A0)x with x as R or W is sent after the Start condition, this
device compares the first seven bits of this byte to its address and
matches. Since SCL and SDA lines of the I²C bus are either open
collector or open drain, 2 pull-up resistors (Rp)on bus for SCL and
SDA are necessary. To minimize crosstalk and to minimize
spikes, a serial termination resister (Rs) close to the SCL and SDA
lines are important for each device on the I²C bus. The value of
Rp and Rs is determined according to the maximum sink current
of the device, supply voltage, bus capacitance, and the number
of devices on the bus. Even though the maximum bus
capacitance of the fast mode specified in the I²C bus is 400pF, it
is always recommended to reduce bus capacitance to get better
signal quality.
Figure 4 shows a sample one-byte read. Figure 5 shows a sample
one-byte write. For more information about the I²C standard,
please consult the Philips™ I²C specification documents.
13
FN6577.2
July 29, 2013