Datasheet

MAX3766
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
14 ______________________________________________________________________________________
Table 3. MAX3766 Fault Response in Latched Shutdown Configuration
High voltage on REF1 causes a failure and latched
shutdown.
REF1
Normal condition for circuit operation.ENABLE
Modulation current is increased. Either the APC
circuit will reduce power levels, or an overcurrent
will be detected at MD, causing a failure signal
and latched shutdown.
REF2, TC, MOD
Normal condition for circuit operation.SAFETY
Normal condition for circuit operation.OUT-
No effect on circuit.
FAIL
Forces output to either constant 1 or 0. APC main-
tains the power level at the programmed level.
IN+, IN-
PIN
Depending upon the setting of R
POWERSET
,
there is either no effect, or a latched shutdown.
BIASMAX
CIRCUIT RESPONSE TO OVERVOLTAGE
OR SHORT TO V
CC
Modulation and bias currents are reduced or off;
no hazard exists.
Modulation and bias currents are shut down.
Modulation current is reduced; no hazard exists.
Safety shutdown features are disabled, but a
hazard is not created.
Forces output to be logic 1. APC maintains the
power level at the programmed level.
No effect on circuit.
Forces output to either constant 1 or 0. APC main-
tains the power level at the programmed level.
Bias current reduction causes a low laser output,
resulting in a latched shutdown.
CIRCUIT RESPONSE TO UNDERVOLTAGE
OR SHORT TO GROUND
Voltage increase at these pins will turn off the
laser.
OUT+, BIAS
High laser output asserts FAIL. A complete short
will destroy the laser, eliminating the hazard. A
resistive short may cause a hazard. External
circuitry combined with the FAIL signal may be
used to protect against a resistive short (Figure 10).
Laser output increases, but is limited by the setting
of R
BIASMAX
.
POWERSET Laser output decreases.
Voltage increase at MD causes a failure and output
current shutdown.
MD
Voltage decrease at MD causes a failure and
output current shutdown.