3.0V to 5.5V, 1.25Gbps/2.5Gbps

LAN Laser Drivers

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17

PIN NAME

CIRCUIT RESPONSE TO OVERVOLTAGE OR

CIRCUIT RESPONSE TO UNDERVOLTAGE OR

SHORT TO GROUND

EN

Normal condition for circuit operation

Fault state* occurs

Does not affect laser power

FAULT

Does not affect laser power

Does not affect laser power

POR

Does not affect laser power

Normal condition for circuit operation

EN

Fault state* occurs

Fault state* occurs

PORDLY

Does not affect laser power

LV

Does not affect laser power

If POL is a TTL LOW, a fault state* occurs; other-

wise, the circuit is in normal operation

POL

If POL is a TTL HIGH, a fault state* occurs; other-

wise, the circuit is in normal operation

MON

(also MAX3288/

MAX3298)

In common cathode without photodiode configura-

tion, a fault state* occurs; otherwise, does not affect

laser power

Fault state* occurs

If POL is a TTL LOW, a fault state* occurs; other-

wise, the circuit is in normal operation

POL

If POL is a TTL HIGH, a fault state* occurs; other-

wise, the circuit is in normal operation

Does not affect laser power

SHDNDRV

(also MAX3287/

MAX3297/MAX3289/

MAX3299

Does not affect laser power. If optional FET is used,

the laser output is shut off.

FLTDLY

Any fault that occurs cannot be reset. Does not

affect laser power.

Does not affect laser power

Does not affect laser power

IN+, IN-

Does not affect laser power

In common-cathode configurations, a fault state*

occurs; otherwise, does not affect laser power

REF

Fault state* occurs

Fault state* occurs

MD

Fault state* occurs

OUT+, OUT-

Does not affect laser power

Does not affect laser power

Fault state* occurs

MODSET

Does not affect laser power

In common-anode configurations, the laser bias

current is shut off. In common cathode, high laser

power triggers a fault state.* Shutdown occurs if a

shutdown FET (M1) is used (Figures 9, 10).

BIASDRV

In common-cathode configurations, the laser bias

current is shut off. In common anode, high laser

power triggers a fault state.* Shutdown occurs if a

shutdown FET (M1) is used. If shutdown FET is not

used, other means must be used to prevent high

laser power.

Fault state* occurs

TC

Does not affect laser power

Table 5. Circuit Response to Various Single-Point Faults

*A fault state asserts the FAULT pins, disables the modulator outputs, disables the bias output, and asserts the SHDNDRV pin.

FAULT

Does not affect laser power

Does not affect laser power