MAX24001TL+ Maxim Integrated, MAX24001TL+ Datasheet - Page 20

• Manufacturer Part Number: MAX24001TL+
• Description: Laser Drivers 2.5G Burst Mode Laser Xcvr
• Manufacturer: Maxim Integrated
• Type: Laser Driverr

Specifications of MAX24001TL+

• Rohs: yes
• Data Rate: 2.5 Gbps
• Operating Supply Voltage: 3 V to 3.6 V
• Supply Current: 136 mA
• Maximum Operating Temperature: + 95 C
• Package / Case: TQFN-40
• Maximum Power Dissipation: 2857.1 mW
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Part # Aliases: 90-Y24001+XS1

At the end of the fast-start algorithm, the laser output stage switches from sinking DC I
amplitude signal. This may result in a brief current spike. A facility is provided to optionally shut down the
modulation current through the laser during this transition period (D). Use the fstart_recovery_en and
fstart_recovery_time registers to shut down the modulation current for 0, 1 or 2 iterations.
APC Loop Bandwidth
The apc_loop_gain register adjusts the gain of the APC control loop. Loop bandwidth is calculated as a function of
apc_loop_gain:
Where: mondac_lsb = 0.78μA
0000
0001
0010
:
1100
1101
1110
1111
Power Monitoring
A power monitoring circuit generates a digital measure of MPD current (laser power) based on time-averaged
samples taken during bursts when the laser is enabled. It has three settings in order to accommodate the wide
range of monitor photodiode currents. The range setting (mpd_range) is chosen at the time that the module is
calibrated, and does not change during normal operation of the APC loop. The unfiltered, 8-bit digital measure of
MPD current is used internally by the APC loop.
Tracking error in the TOSA means that the MPD current may vary over temperature in a nonlinear way for a given
laser optical power. If the temperature-indexed tracking error lookup table (LUT) is enabled then the digital
measure of MPD current is multiplied by the values read from the LUT. Each entry in the LUT represents a number
in the range 0.5 (00h) to 1.5 (FFh), and 80h represents unity gain.
Maxim Integrated
mpd_range
apc_loop_gain
00
01
10
biasdac_lsb = 92.5μA
f
kmpd
CLOCK
PD MIRROR GAIN
Bandwidth =
= 64MHz (typical)
= 0.0625 when mpd_range = 10
1/16
1/4
GAIN
2
2
2
:
2
2
2
1
1
-15
-14
-13
-3
-2
-1
0.25 when mpd_range = 01
1 when mpd_range = 00
=
I
MON
2
2
apc_loop_gain - 15
apc_loop_gain - 15
OPERATING RANGE (µA)
400 to 2000
100 to 800
40 to 200
2 * π * 16 * mondac_lsb
* k
* k
elec
elec
* k
* k
mpd
mpd
* (biasdac_lsb * 4) * f
* 3.02x10
6
clock
MON
/2 on TX_OUT to full
20