622Mbps LAN/WAN Laser Driver with

Automatic Power Control and Safety Shutdown

6

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Pin Description

ENABLE is a TTL-compatible input. When low or open, this pin disables the output modulation and bias

current.

ENABLE

10

A capacitor to ground at SAFETY determines the turn-on delay for the safety circuits. If SAFETY is

grounded or TTL low, internal safety shutdown features are disabled. A TTL high at SAFETY enables the

internal safety shutdown features.

SAFETY

11

The FAIL output asserts low if the voltage at MD is above or below nominal. FAIL also asserts if REF1 is

inadvertently tied to the positive supply. FAIL has TTL-compatible output voltage levels.

FAIL

12

Supply Voltage for the Output Current Drivers

13

Inverting Modulation-Current Output

OUT-

14

Ground. All grounds must be connected.

GND

5, 8

Inverting Data Input

IN-

6

Noninverting Data Input

IN+

7

9

The current into MOD programs the laser modulation current. Connect MOD to REF2 with a resistor or

potentiometer.

MOD

4

REF2 is the reference voltage used to program the modulation current. The tempco of REF2 is pro-

REF2

3

PIN

TC directly to REF1 produces the minimum tempco. Leaving TC unconnected produces the maximum

tempco.

TC

2

The current into BIASMAX sets the maximum laser bias current. Connecting BIASMAX directly to REF1

allows the largest possible bias current.

BIASMAX

1

FUNCTION

NAME

Ground for the Output Current Drivers

GNDOUT

17

Input for the laser monitor photodiode current.

MD

18

The current into POWERSET programs the average optical output power when automatic power

control is used.

POWERSET

19

REF1 is a voltage reference used to program laser bias current and average power.

REF1

20

Noninverting Modulation-Current Output

OUT+

15

Connection for the DC Laser Bias Current

BIAS

16