DS1862B+ Maxim Integrated Products, DS1862B+ Datasheet - Page 16

• 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

Table 2. Temperature Lookup Table
XFP Laser Control and Digital Diagnostic IC
If the largest current range is selected, the maximum
value of FFh (from LUT) corresponds to a 1200μA sink
current. Regardless of the current range, the MODSET
value always consists of 256 steps, including zero.
I
perature-based lookup table, or by three other manual
methods.
Automatic temperature addressed lookup is accom-
plished by an internal or external temperature sensor
controlling an address pointer. This pointer indexes
through 127 previously loaded 8-bit current values
stored in the LUT. Each one of the 127 temperature
slot locations corresponds to a 2°C increment over
the -40°C to +102°C temperature range. Any tempera-
ture above or below these points causes the code in
the first or last temperature slot to be indexed. Both the
internal temperature sensor and an external sensor
connected to AUX2MON are capable of providing a
signal to control the extinction ratio automatically with
an indexed LUT. Table 2 illustrates the relationship
between the temperature and the memory locations in
the LUT.
16
MODSET
TEMPERATURE (°C)
____________________________________________________________________
can be controlled automatically with the tem-
> +102
< -40
+100
+102
+96
+98
-40
-38
-36
…
CORRESPONDING LOOKUP
TABLE ADDRESS
C4h
C5h
C6h
C7h
C7h
80h
80h
81h
82h
…
Table 3. Truth Table for TEN and AEN Bits
Automatic and manual control of MODSET is controlled
by two bits, TEN and AEN, that reside in Table 04h,
Byte B2h. By default (from factory) TEN and AEN are
both set, causing complete automatic temperature-
based lookup. If TEN and/or AEN are altered, the
DS1862 is set to one of the manual modes. Table 3
describes manual mode functionality.
TEN AEN
0
0
1
1
0
1
0
1
Manual mode that allows users to write a
value directly to the LUT VALUE register
(Table 04h, Byte B1h) to drive MODSET. While
in this mode, the LUT INDEX POINTER register
is not being updated, and no longer drives the
LUT VALUE register.
Manual mode that allows users to write a
value directly to the LUT VALUE register
(Table 04h, Byte B1h) to drive MODSET. While
in this mode, the LUT INDEX POINTER register
is still being updated; however, it no longer
drives the LUT VALUE register.
Manual mode that allows users to write a
value to the LUT INDEX POINTER register
(Table 04h, Byte B0), then the DS1862
updates the LUT VALUE register (Table 04h,
Byte B1h) based on the user’s index pointer.
Automatic mode (factory default). This mode
automatically indexes the LUT based on
temperature, placing the resulting LUT
address in the LUT INDEX POINTER register
(Table 04h, Byte B0h). Then the MODSET
setting is transferred from that LUT address to
the LUT VALUE register (Table 04h, Byte B1h).
Lastly, the I
code.
DS1862 LUT FUNCTIONALITY
MODSET
is set to the new MODSET