DS1862AB+ Maxim Integrated Products, DS1862AB+ Datasheet - Page 40

• Manufacturer Part Number: DS1862AB+
• Description: IC LASR CTRLR 7CHAN 5.5V 25CSBGA
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Controller (Fiber Optic)r

Specifications of DS1862AB+

• Data Rate: 10Gbps
• Number Of Channels: 7
• Voltage - Supply: 2.9 V ~ 5.5 V
• Current - Supply: 3mA
• Operating Temperature: -40°C ~ 100°C
• Package / Case: 25-CSBGA
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

XFP Laser Control and Digital Diagnostic IC
CRC-8 includes and requires the explicit starting mem-
ory address to be included as the second transferred
byte. Next, the master transfers the data as the
DS1862A acknowledges. Only 4 bytes can be sequen-
tially written during one transmission while using PEC.
After the master writes the intended number of bytes,
the CRC-8 value should be transmitted. Following the
CRC-8 byte, the master should transmit the CAB byte
(CRC Add-on Byte). At this point, the DS1862A sends
an ACK if the CRC-8 matches its internal calculated
value or a NACK if not. Finally, the master should end
the communication and send a STOP. See Figure 16 for
a graphical representation. The CRC-8 is calculated
starting with the MSB of the memory address pointer,
number of bytes to be written, and the written data. The
master can then poll the last ACK or NACK for suc-
cessful transfer of written data.
For more information on I
to the XFP and/or SMBus 2.0 standard.
Figure 16. I
40
______________________________________________________________________________________
COMMUNICATIONS KEY
WRITE UP TO A 4-BYTE PAGE WITH A SINGLE TRANSACTION USING PEC
READ 1–128 BYTES WITH A DUMMY WRITE CYCLE TO SET THE ADDRESS COUNTER
SR
S
P
S
S
2
1 0 1
1 0 1
START
STOP
REPEATED
START
C PEC Communications Examples
0
DATA
DATA
0
A
N
0
0
DATA
0
0
X X X X X X X X
ACK
NOT
ACK
2
0 0
0 0
C PEC communications, refer
A
A
A
A
WHITE BOXES INDICATE THE MASTER IS
CONTROLLING SDA
SHADED BOXES INDICATE THE SLAVE IS
CONTROLLING SDA
MEMORY ADDRESS
MEMORY ADDRESS
A (IF CRC-8 IS CORRECT)
DATA
8-BIT ADDRESS OR DATA
DATA
A
A
A
Before calibrating, the APC register should be set to a
low value to ensure the laser’s maximum power level is
not exceeded before the power level is calibrated.
Additionally, the ER should be set to a minimum value
to ensure that a data test pattern does not cause the
laser to shut off. Once the APC and ER registers are at
minimal values, enable a data pattern and calibrate the
average power level.
While sending data through the laser diode, increase
the value in the APC register until the light output
matches the desired average power level. The average
power level is the arithmetic average of the ‘1’ and ‘0’
power levels.
NUMBER OF BYTES
NUMBER OF BYTES
P
DATA
A
Calibrating APC and Extinction Ratio
CRC-8 VALUE
Applications Information
NOTE:
ALL BYTES ARE SENT MOST SIGNIFICANT BIT FIRST.
THE FIRST BYTE SENT AFTER A START CONDITION IS
ALWAYS THE SLAVE ADDRESS FOLLOWED BY THE
READ/WRITE BIT.
Calibrating the Average Power Level
A
A
A
SR
1 0 1
CRC-8 VALUE
DATA
N
0
P
0
0
0 0
A
A
A