DS1864T+ Maxim Integrated Products, DS1864T+ Datasheet - Page 21

• Manufacturer Part Number: DS1864T+
• Description: IC LASER CTRLR 1CHAN 5.5V 28TQFN
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Controller (Fiber Optic)r

Specifications of DS1864T+

• Number Of Channels: 1
• Voltage - Supply: 2.97 V ~ 5.5 V
• Current - Supply: 3mA
• Operating Temperature: -40°C ~ 95°C
• Package / Case: 28-WFQFN Exposed Pad
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

shutdown signals. Alarm and warning thresholds keep
the system functioning within user-programmed para-
meters. All alarm and warning flags are active high.
Fast-trip alarms and warnings can be configured to
overwrite the diagnostic flags for the same function.
Laser safety features are also implemented to accept
and send alarm signals to control laser activity.
The three monitor channels (MON1, MON2, and MON3)
have associated fast channels. A sequencer with fast-trip
comparators monitors the three voltage channels: MON1
(Bias Current (IBI)), MON2 (Transmitted Power (TXP)),
and MON3 (Received Power (RIN)). These signals are the
same raw (uncalibrated) signals used for the diagnostic
circuits. Five fast-trip flags (alarms and warnings) are
generated: high-bias alarm (HBAL), high-bias warning
(HBWA), high transmitted power (HTXP), low transmitted
power (LTXP), and loss of received signal (LOS), see
Table 6. MON3 Hysteresis Threshold
Values
*This is the minimum reported course mode conversion.
Table 7. MON3 Configuration Registers
*Table 04h in DS1852 configuration or Table 01h in DS1859
configuration.
GAIN REGISTER
OFFSET REGISTER
RIGHT SHIFT REGISTER
RSSIC AND RSSIF BITS
RSSIS BIT
MON3 MEASUREMENT
# OF RIGHT
SHIFTS
0
1
2
3
4
5
6
7
FINE MODE MAX
(HEX)
7FFC
3FFE
FFF8
1FFF
0FFF
07FF
03FF
01FF
FINE MODE
Table 04h*
Table 04h*
Table 04h*
A8 to A9h,
98 to 99h,
68 to 69h, Lower Memory
8Fh,
77h, Lower Memory
8Ah, Table 04h*
____________________________________________________________________
COURSE MODE
MIN* (HEX)
3C00
1E00
03C0
01E0
F000
7800
0F00
0780
AA to ABh,
Table 04h*
Table 04h*
9A to 9Bh,
COURSE
Fast-Trips
N/A
SFP Laser Controller and
Figure 12. These flags are located in Lower Memory, byte
73h. These flags are latched temporarily by design as
required by the sequencer. In order to disable a com-
parator, set its threshold to 00h for low flags and FFh for
high flags. The FT_enable bit (bit 3, byte 80h, Table 04h
(Table 01h in DS1859 configuration)) determines if fast-
trip alarms are enabled or disabled.
The thresholds for HBAL and HBWA can be pro-
grammed to be temperature compensated. Registers
B0h to B7h for HBAL and B8h to BFh for HBWA of
Table 04h (Table 01h in DS1859 configuration) are
where the temperature-compensated alarm and warn-
ing thresholds are stored. Register DBh of Table 04h
(Table 01h in DS1859 configuration) is the location of
the HTXP programmable threshold. Register DCh of
Figure 15. Dual-Range Functionality Flowchart
TIMESLICE RESULT IN A
CONVERSION RESULT
MODE CONVERSION
DID CURRENT FINE
DID PRIOR MON3
COURSE CONV.?
PERFORM FINE
END OF MON3
MODE CONV.
REACH MAX?
(RSSIS = 1?)
RSSIS BIT = 0
REPORT FINE
TIMESLICE
TIMESLICE
MON3
N
N
Diagnostic IC
Y
Y
CONVERSION RESULT
WAS CURRENT FINE
MODE CONVERSION
PERFORM COURSE
REPORT COURSE
MODE CONV. <
COURSE MIN?
RSSIS BIT = 1
Y
N
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