MAX3261 datasheet(5/12 Pages) MAXIM

5 / 12 page

Single +5V, Fully Integrated,

1.25Gbps Laser Diode Driver

_______________________________________________________________________________________

______________________________________________________________Pin Description

NAME

FUNCTION

1, 2, 25,

27, 29

GNDA

Ground for Bias and Modulation Current Drivers

IPIN

Monitor Photodiode Current Input. Connect IPIN to photodiode’s anode.

SLWSTRT

Slow-Start Capacitor Input. Connect capacitor to ground or leave unconnected to set start-up time,

tSTARTUP = 25.4kΩ (CSLWSTRT + 2pF).

5, 9,

11, 13

GNDB

Ground for Voltage Reference and Automatic Power-Control Circuitry

FAILOUT

Failout Output. Active-low, open-collector TTL output indicates if automatic power-control loop is out

of regulation due to insufficient monitor-diode current (when VIPIN is below the 2.6V threshold).

Connect FAILOUT to VCC_ through a 2.7kΩ pull-up resistor.

IPINSET

Monitor Photodiode Programming Input. Connect IPINSET to VREF1 or VREF2 through a resistor to

set the monitor current when using automatic power control (see

Typical Operating Characteristics).

VREF2

Temperature-Compensated Reference Output. VREF2 is internally connected to VREF1.

VREF1

Temperature-Compensated Reference Output. VREF1 is internally connected to VREF2.

ENB-

Inverting Enable TTL Input. Output currents are enabled only when ENB+ is high and ENB- is low.

14, 15, 18

VCCB

+5V Supply Voltage for Voltage Reference and Automatic Power-Control Circuitry. Connect VCCB to

the same potential as VCCA, but provide separate bypassing for VCCA and VCCB.

VIN-

Inverting PECL Data Input

VIN+

Noninverting PECL Data Input

IBIASFB

Bias-Feedback Current Output. Output from automatic power-control circuit. Connect to IBIASSET

when using APC.

OSADJ

Overshoot-Adjust Input. Connect to internal voltage reference through a resistor to adjust the over-

shoot of the modulation output signal (see

Typical Operating Characteristics).

IBIASSET

Laser Bias Current-Programming Input. Connect to internal voltage reference through a resistor to set

bias current (see

Typical Operating Characteristics). IIBIASOUT = 40 x (IIBIASSET + IIBIASFB).

IMODSET

Laser Modulation Current-Programming Input. Connect to internal voltage reference through a resistor

to set modulation current (see

Typical Operating Characteristics). IMOD = 20 x IIMODSET.

IBIASOUT

Laser Bias Current Output. Connect to laser cathode through an R-L compensation network (see the

Bias Network Compensation section).

OUT-

Modulation Output. When VIN+ is high and VIN- is low, OUT- sinks IMOD.

30, 31, 32

VCCA

+5V Supply Voltage for Bias and Modulation Current Drivers. Connect VCCA to the same potential as

VCCB, but provide separate bypassing for VCCA and VCCB.

OUT+

Modulation Output. When VIN+ is low and VIN- is high, OUT+ sinks IMOD.

ENB+

Noninverting Enable TTL Input. Output currents are enabled only when ENB+ is high and ENB- is low.

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