ADN2525ACPZ-WP Analog Devices Inc, ADN2525ACPZ-WP Datasheet - Page 11

IC,Laser Diode/LED Driver,LLCC,16PIN,PLASTIC

ADN2525ACPZ-WP

Manufacturer Part Number
ADN2525ACPZ-WP
Description
IC,Laser Diode/LED Driver,LLCC,16PIN,PLASTIC
Manufacturer
Analog Devices Inc
Type
Laser Diode Driver (Fiber Optic)r
Datasheet

Specifications of ADN2525ACPZ-WP

Data Rate
10.7Gbps
Number Of Channels
1
Voltage - Supply
3.07 V ~ 3.53 V
Current - Supply
39mA
Current - Modulation
80mA
Current - Bias
100mA
Operating Temperature
-40°C ~ 85°C
Package / Case
16-VFQFN, CSP Exposed Pad
Mounting Type
Surface Mount
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
excellent transmission line termination, while dissipating less
power than a traditional resistor passive back-termination. No
portion of the modulation current flows in the active back-
termination resistance. All of the preset modulation current
IMOD, the range specified in Table 1, flows in the external load.
The equivalent circuits for MSET, IMODP, and IMODN are
shown in Figure 26 and Figure 27. The two 25 Ω resistors in
Figure 27 are not real resistors; they represent the active back-
termination resistance.
The recommended configuration of the MSET, IMODP,
and IMODN pins is shown in Figure 28. See Table 6 for
recommended components.
Figure 28. Recommended Configuration for the MSET, IMODP, and IMODN Pins
V
MSET
Figure 27. Equivalent Circuit of the IMODP and IMODN Pins
MSET
Figure 26. Equivalent Circuit of the MSET Pin
MSET
ADN2525
VCC
GND
25Ω
IMODN
IMODP
IBIAS
IMODN
VCC
3.3Ω
800Ω
200Ω
Z
Z
0
0
= 25Ω
= 25Ω
3.3Ω
IMODP
VCC
VCC
VCC
L
L
25Ω
C
C
VCC
L
L
VCC
Z
Z
0
0
= 25Ω
= 25Ω
TOSA
Rev. A | Page 11 of 16
The ratio between the voltage applied to the MSET pin and the
differential modulation current available at the IMODP and
IMODN pins is a function of the load resistance value, as shown
in Figure 29.
Using the resistance of the TOSA, the user can calculate the
voltage range that should be applied to the MSET pin to generate
the required modulation current range (see the example in the
Applications Information section).
The circuit used to drive the MSET voltage must be able to
drive the 1 kΩ resistance of the MSET pin. To be able to drive
80 mA modulation currents through the differential load, the
output stage of the ADN2525 (the IMODP and IMODN pins)
must be ac-coupled to the load. The voltages at these pins have
a dc component equal to VCC and an ac component with
single-ended, peak-to-peak amplitude of IMOD × 25 Ω. This is
the case even if the load impedance is less than 50 Ω differential,
because the transmission line characteristic impedance sets the
peak-to-peak amplitude. For proper operation of the output stage,
the voltages at the IMODP and IMODN pins must be between
the compliance voltage specifications for this pin over supply,
temperature, and modulation current range, as shown in Figure 30.
See the Applications Information section for examples of
headroom calculations.
210
200
190
180
170
160
150
140
130
120
110
100
90
80
70
60
0
Figure 29. MSET Voltage-to-Modulation Current Ratio vs.
5
10
DIFFERENTIAL LOAD RESISTANCE
15
Differential Load Resistance
MINIMUM
20
TYPICAL
25
MAXIMUM
30
35
40
45
ADN2525
50
55

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