MAX3863ETJ+T Maxim Integrated Products, MAX3863ETJ+T Datasheet - Page 8

• Manufacturer Part Number: MAX3863ETJ+T
• Description: IC LASR DRVR 2.7GBPS 3.6V 32TQFN
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Driver (Fiber Optic)r

Specifications of MAX3863ETJ+T

• Data Rate: 2.7Gbps
• Number Of Channels: 1
• Voltage - Supply: 3.15 V ~ 3.6 V
• Current - Supply: 58mA
• Current - Modulation: 80mA
• Current - Bias: 100mA
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-WFQFN Exposed Pad
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

the output-enable must be true to enable bias and
modulation currents.
The APC loop is enabled when an external capacitor is
placed between the APCFILT1 and APCFILT2 pins.
This capacitor sets the time constant of the APC loop.
To open the APC loop, the APCFILT1 pin is shorted to
ground. This shorts the feedback from the monitor
diode and causes the bias current to rise to the maxi-
mum value set by the BIASMAX pin.
The APC loop keeps the average optical power from the
laser constant. An external filter capacitor is used to stabi-
lize the APC loop. The typical capacitor value is 0.01µF.
The MAX3863 provides an APC failure monitor
(TTL/CMOS) to indicate an APC loop tracking failure.
FAIL is set low when the APC loop cannot adjust the
bias current to maintain the desired monitor current.
The MAX3863 provides short-circuit protection for mod-
ulation, bias, and monitor current sources. If BIASMAX,
MODSET, or APCSET is shorted to ground, the bias
and modulation output are turned off and FAIL is active.
The MAX3863 features monitor outputs for bias current
(BIASMON), modulation current (MODMON), and moni-
tor diode current (MDMON). The monitors are realized
by mirroring a fraction of the current and developing a
voltage across an external resistor. For the specified
2.7Gbps Laser Driver with Modulation
Compensation
Figure 2. Required Input Signal, Setup/Hold-Time Definition and Output Polarity
8
_______________________________________________________________________________________
Short-Circuit Protection
DATA+
DATA-
(DATA+) - (DATA-)
CLK+
CLK-
I
MOD
APC Failure Monitor
APC Loop Enable
Current Monitors
t
SU
APC Filter
t
HD
voltage to monitor diode current, use an external 4kΩ
resistor at the MDMON output. Resistors for BIASMON
and MODMON are 100Ω. The minimum voltage at the
BIASMON and MODMON must be 2.1V for compliance.
When designing a laser transmitter, the optical output is
usually expressed in terms of average power and
extinction ratio. Table 1 shows relationships helpful in
converting between the optical average power and the
modulation current. These relationships are valid only if
the mark density and duty cycle of the optical wave-
form are 50%.
For a desired laser average optical power (P
optical extinction ratio (r
rent can be calculated based on the laser slope effi-
ciency (η) using the equations in Table 1.
Determine static bias and modulation current require-
ments from the laser threshold current and slope efficien-
cy. To use the APC loop with modulation compensation,
V
V
MODMON
BIASMON
V
V
V
ID
IS
IS
7mA TO 80mA
= 0.2V
V
= 0.1V TO 0.8V
= 0.1V TO 0.8V
MDMON
Laser Current Compensation
P-P
=
=
TO 1.6V
e
V
V
), the required modulation cur-
CC
CC
=
Design Procedure
P-P
I
−
−
MD
4
I
I
BIAS
MOD
40
45
×
4 Ω
k
×
×
Requirements
100Ω
100Ω
AVG
) and