Rainbow Electronics MAX3737 - Manual (Page 7)

MAX3737
Multirate Laser Driver with Extinction
Ratio Control
Pin Description
PIN NAME FUNCTION
1, 10, 15, 16 GND Ground
2 TX_DISABLE
Transmitter Disable, TTL. Laser output is disabled when TX_DISABLE is asserted high or left
unconnected. The laser ouput is enabled when this pin is asserted low.
3, 6, 11, 18, 23 V CC +3.3V Supply Voltage
4 IN+ Noninverted Data Input
5 IN- Inverted Data Input
7 PC_MON
Photodiode-Current Monitor Output. Current out of this pin develops a ground-referenced voltage
across an external resistor that is proportional to the monitor-diode current.
8 BC_MON
Bias-Current Monitor Output. Current out of this pin develops a ground-referenced voltage across
an external resistor that is proportional to the bias current.
9 MC_MON
Modulation-Current Monitor Output. Current out of this pin develops a ground-referenced voltage
across an external resistor that is proportional to the modulation current amplitude.
12 TX_FAULT Open-Collector Transmit Fault Indicator (Table 1)
13 SHUTDOWN
Shutdown Driver Output. Voltage output to control an external transistor for optional shutdown
circuitry.
14 VBS
Bias Voltage Sense. Isolated tap (3k Ω ±15%) on the bias output reduces component count when a
precision bias sense resistor is used.
17 BIAS Laser Bias-Current Output
19, 20 OUT-
Inverted Modulation-Current Output (Connect Pins 19 and 20 Together). I MOD flows into this pin
when input data is low.
21, 22 OUT+
Noninverted Modulation-Current Output (Connect Pins 21 and 22 Together). I MOD flows into this pin
when input data is high.
24 MD
Monitor Photodiode Input. Connect this pin to the anode of a monitor photodiode. A capacitor to
ground is required to filter the high-speed AC monitor photocurrent.
25 VMD
Monitor Photodiode Voltage Sense. Isolated tap (3k Ω ±15%) on the MD input reduces component
count when a precision photodiode current-sense resistor is used.
26 APCFILT1
Connect a capcitor (C APC ) between pin 26 (APCFILT1) and pin 27 (APCFILT2) to set the dominant
pole of the APC feedback loop.
27 APCFILT2 (See Pin 26.)
28 APCSET A resistor connected from this pin to ground sets the desired average optical power.
29 MODSET
A resistor connected from this pin to ground sets the desired constant portion of the modulation
current.
30 MODBCOMP
Modulation-Current Compensation from Bias. Couples the bias current to the modulation current.
Mirrors I
BIAS
through an external resistor. Leave open for zero coupling.
31 TH_TEMP
Threshold for Temperature Compensation. A resistor at this pin programs the temperature, above
which compensation is added to the modulation current.
32 MODTCOMP
Modulation-Current Compensation from Temperature. A resistor at this pin sets the temperature
coefficient of the modulation current when above the threshold temperature. Leave open for zero
temperature compensation.
EP Exposed Pad
Ground. Solder the exposed pad to the circuit board ground for specified thermal and electrical
performance.
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