MAX3867ECM Maxim Integrated Products, MAX3867ECM Datasheet - Page 10

• Manufacturer Part Number: MAX3867ECM
• Description: Laser Driver Integrated Circuits (ICs)
• Manufacturer: Maxim Integrated Products

Specifications of MAX3867ECM

• Case: TQFP
• Dc: 02+

pattern-dependent jitter, three external components
must be properly chosen: capacitor C
nates the APC loop time constant; pull-up inductor L
and AC-coupling capacitor C
To filter out noise effects and guarantee loop stability,
the recommended value for C
in an APC loop bandwidth of 10kHz or a time constant
of 16µs. As a result, the pattern-dependent jitter associ-
ated with an APC loop time constant can be ignored.
The time constant associated with the output pull-up
inductor (L
also impact the pattern-dependent jitter. For such a
second-order network, the PDJ due to the low frequen-
cy cutoff will be dominated by L
2.5Gbps, the recommended value for C
During the maximum CID period t
to limit the peak voltage droop to less than 12% of the
average (6% of the amplitude). The time constant can
be estimated by:
If
To reduce the physical size of this element (L
SMD ferrite beads is recommended (Figure 2).
The MAX3867 data and clock inputs are PECL-compat-
ible. However, it is not necessary to drive the MAX3867
with a standard PECL signal. As long as the specified
common-mode voltage and the differential voltage
swings are met, the MAX3867 will operate properly.
The junction temperature of the MAX3867 dice must be
kept below +150°C at all times. The total power dissipa-
tion of the MAX3867 can be estimated by the following:
where I
MAX
cal laser forward voltage.
+3.3V, 2.5Gbps SDH/SONET Laser Driver
with Automatic Power Control
10
LP
, I
______________________________________________________________________________________
= L
MOD
BIAS
Junction temperature = P(W)
P
/25Ω, and t = 100UI = 40ns, then L
P
P = V
is the modulation current, and V
), and the AC-coupling capacitor (C
is the maximum bias current set by R
+ I
Input Termination Requirement
MOD
Calculate Power Consumption
CC
·
12% = 1 - e
(V
V
CC
CC
LP
+ (V
- 25Ω
= 7.8t
D
APC
CC
.
-t
·
/
- V
I
P
MOD
L P
is 0.1µF. This results
,
. For a data rate of
it is recommended
f
)
·
APC
·
48 (°C/W)
/ 2)
I
BIAS
D
, which domi-
f
is 0.056µF.
is the typi-
P
P
= 7.8µH.
), use of
D
), will
BIAS-
P
;
The following is an example of how to set up the
MAX3867.
A communication-grade laser should be selected for
2.488Gbps applications. Assume the laser output aver-
age power is P
r
+85°C, and the laser diode has the following character-
istics:
The desired monitor diode current is estimated by
I
graph in the Typical Operating Characteristics shows
that R
To achieve a minimum extinction ratio (r
temperature and lifetime, calculate the required extinc-
tion ratio at 25°C. Assuming r
optical power P
required modulation current is 1.81(mW) / 0.05(mW/mA)
= 36.2mA. The I
Operating Characteristics shows that R
be 4.8kΩ.
Calculate the maximum threshold current (I
T
50mA, the maximum bias current should be:
In this example, I
R
shows that R
MD
e
A
BIASMAX
Wavelength:
Threshold Current:
Threshold Temperature
Coefficient:
Laser to Monitor Transfer:
Laser Slope Efficiency:
= 6.6 (8.2dB), the operating temperature is -40°C to
= +85°C and end of life. Assuming I
= P
APCSET
AVE
graph in the Typical Operating Characteristics
BIASMAX
I
·
BIASMAX
should be 6.0kΩ.
AVE
p-p
Applications Information
MON
MOD
BIASMAX
= 1.81mW according to Table 1. The
= 0dBm, minimum extinction ratio is
should be 3.2kΩ.
vs. R
= 200µA. The I
= I
TH(MAX)
MODSET
= 68.1mA. The I
Determine R
Determine R
Determine R
e
= 20, the peak-to-peak
at +25°C
TH
TH
MON
+ I
= 1.3µm
= 0.05mW/mA
graph in the Typical
= 22mA at +25°C
MOD
= 1.3%/°C
MD
= 0.2A/W
Select Laser
e
MODSET
) of 6.6dB over
/2
vs. R
BIASMAX
TH(MAX)
TH(MAX)
BIASMAX
MODSET
APCSET
APCSET
should
) at
vs.
=