DS1862B+ Maxim Integrated Products, DS1862B+ Datasheet - Page 40

• Manufacturer Part Number: DS1862B+
• Description: IC LASR CTRLR 7CHAN 5.5V 25CSBGA
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Controller (Fiber Optic)r

Specifications of DS1862B+

• 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 DS1862
acknowledges. Only 4 bytes can be sequentially 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 DS1862 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 repre-
sentation. 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 successful 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