AD8615AUJZ Analog Devices Inc, AD8615AUJZ Datasheet - Page 13

• Manufacturer Part Number: AD8615AUJZ
• Description: OP AMP, PRECISION RRI/O, SMD, 8615
• Manufacturer: Analog Devices Inc

Specifications of AD8615AUJZ

• Op Amp Type: Precision
• No. Of Amplifiers: 1
• Bandwidth: 24MHz
• Slew Rate: 12V/µs
• Supply Voltage Range: 2.7 To 5.5V
• Amplifier Case Style: TSOT-23
• No. Of Pins: 5
• Operating Temperature Range: -40°C To
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

HIGH SPEED PHOTODIODE PREAMPLIFIER
The AD8615/AD8616/AD8618 are excellent choices for I-to-V
conversions. The very low input bias, low current noise, and
high unity-gain bandwidth of the parts make them suitable,
especially for high speed photodiode preamps.
In high speed photodiode applications, the diode is operated
in a photoconductive mode (reverse biased). This lowers the
junction capacitance at the expense of an increase in the
amount of dark current that flows out of the diode.
The total input capacitance, C1, is the sum of the diode and op
amp input capacitances. This creates a feedback pole that causes
degradation of the phase margin, making the op amp unstable.
Therefore, it is necessary to use a capacitor in the feedback to
compensate for this pole.
To get the maximum signal bandwidth, select
where f
ACTIVE FILTERS
The low input-bias current and high unity-gain bandwidth
of the AD8616 make it an excellent choice for precision filter
design.
Figure 45 shows the implementation of a second-order, low-
pass filter. The Butterworth response has a corner frequency
of 100 kHz and a phase shift of 90°. The frequency response
is shown in Figure 46.
C
2
U
=
is the unity-gain bandwidth of the amplifier.
I
D
–V
BIAS
Figure 44. High Speed Photodiode Preamplifier
2
π
Figure 45. Second-Order, Low-Pass Filter
R
C
1.1k Ω
V
R
IN
f 2
1
SH
U
C
D
2nF
1.1k Ω
1nF
C
IN
V
V
V–
V+
CC
EE
–
+
–2.5V
+2.5V
V–
V+
C2
R2
Rev. C | Page 13 of 20
POWER DISSIPATION
Although the AD8615/AD8616/AD8618 are capable of
providing load currents up to 150 mA, the usable output, load
current, and drive capability is limited to the maximum power
dissipation allowed by the device package.
In any application, the absolute maximum junction temperature
for the AD8615/AD8616/AD8618 is 150°C. This should never
be exceeded because the device could suffer premature failure.
Accurately measuring power dissipation of an integrated circuit
is not always a straightforward exercise; Figure 47 is a design aid
for setting a safe output current drive level or selecting a heat
sink for the package options available on the AD8616.
Figure 46. Second-Order Butterworth, Low-Pass Filter Frequency Response
–10
–20
–30
–40
10
1.5
1.0
0.5
Figure 47. Maximum Power Dissipation vs. Ambient Temperature
0
0
0.1
0
20
1
10
40
MSOP
TEMPERATURE ( ° C)
SOIC
FREQUENCY (Hz)
AD8615/AD8616/AD8618
100
60
1k
80
10k
100
100k
120
1M
140