DS1862B+ Maxim Integrated Products, DS1862B+ Datasheet - Page 17

• 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

The DS1862 has seven monitored voltage signals that
are polled in a round-robin multiplexed sequence and
are updated with the frame rate, t
are read as 16-bit values, but have 13-bit resolution,
and with the exception of temperature measurements,
all channels are stored as unsigned values. The resulting
16-bit value for all monitored channels, except internal
temperature, is calculated by internally averaging the
analog-to-digital result eight times. The resulting internal
temperature monitor channel is averaged 16 times. See
the Internal Calibration section for a complete descrip-
tion of each channel’s method(s) of internal calibration.
The AUX1MON, AUX2MON, and V
nels are optional and can be disabled. This feature
allows for shorter frame rate for the essential monitor
channels. Channels that cannot be disabled are inter-
nal temperature, BMD, RSSI, and IBIASMON. A table of
full-scale (FS) signal values (using factory internal cali-
bration without right shifting) and the resulting FS code
values for all seven channels is provided in Table 4.
The DS1862 is capable of measuring temperature on
three different monitor channels: internal temperature
sensor, AUX1MON, and AUX2MON. Only the internal
temperature and AUX2MON channels are capable of
indexing the LUT to control the extinction ratio. To use
an external temperature sensor on AUX2MON, the
TEMP_INT/EXT bit in Table 04h, Byte 8Bh, must be set.
While AUX2MON controls the extinction ratio, the inter-
nal temperature sensor does not stop running; despite
extinction ratio control by AUX2MON, it is this internal
temperature signal that continues to control the status
of temperature flags. Also, when TEMP_INT/EXT = 1,
the internal temperature clamps at -40°C and
+103.9375°C, and when TEMP_INT/EXT = 0 it clamps at -
120°C and +127.984°C. AUX2MON, however, does have
its own flag to indicate an out-of-tolerance condition and
assert the INTERRUPT pin.
Table 4. Monitor Channel FS and LSB Detail
Temperature
V
IBIASMON
RSSI
AUX1MON
AUX2MON
BMD (TX-P)
CC2/3
SIGNAL
Measuring Temperature—Internal or External
XFP Laser Control and Digital Diagnostic IC
+FS SIGNAL
127.984°C
6.5528V
2.4997V
2.4997V
6.5528V
6.5528V
1.5mA
Monitor Channels
FRAME
CC2/3
____________________________________________________________________
. All channels
monitor chan-
+FS (hex)
7FF8
FFF8
FFF8
FFF8
FFF8
FFF8
FFF8
Both AUX1MON and AUX2MON can be used to mea-
sure temperature as a function of voltage on their
respective pins. They can be enabled by selecting
either 0h or 4h from Table 5. Internal (or external) cali-
bration may be required to transmute the input voltage
to the desired two’s-complement digital code, readable
from the result registers in lower memory, Bytes 6Ah,
6Bh, 6Ch, 6Dh.
The DS1862 has the flexibility to internally measure
either V
V
01h, Byte DCh. To remove V
monitor update scheme, despite having V
selected to be monitored, the Reserve_EN bit in Table
04h, Byte 8Bh can be programmed to a 0. The analog
power-on-reset flag, POA, indicates the status of V
power supply. Even though POA seems to behave simi-
larly to V
rate and has no connection.
BMD and BIASSET are used to control and monitor the
laser functionality. Regardless of the set BMD current in
the APC register, the DS1862 measures BMD pin cur-
rent and uses this value not only to adjust the current
on the BIASSET pin, but also to monitor TX-P as well.
The IBIASMON pin is used to input a voltage signal to
the DS1862 that can be used to monitor the bias cur-
rent through the laser. This monitor channel does not
drive the HIGH BIAS quick-trip (QT) alarms for safety
RESERVE_EN
CC3
-FS SIGNAL
-120°C
0mA
is user selectable by the V
0V
0V
0V
0V
0V
0
0
1
1
Measuring APC and Laser Parameters—BMD,
CC2
CC2/3
or V
monitor channel, it is completely sepa-
CC3
V
CC2/3_
to monitor supply voltage. V
0
1
0
1
-FS (hex)
SEL
8800
0000
0000
0000
0000
0000
0000
CC2/3
V
V
V
V
CC2/3
CC2/3
CC3
CC2
CC2/3
from the round-robin
Measuring V
is being measured.
is being measured.
IBIASMON, RSSI
result not enabled.
result not enabled.
_SEL bit in Table
RESULT
0.0625°C
22.888nA
38.147μV
38.147μV
38.147μV
38.147μV
CC2
100μV
LSB
or V
CC2
CC2/3
CC3
CC3
17
or