AD712 Analog Devices, AD712 Datasheet - Page 16

• Manufacturer Part Number: AD712
• Description: Precision, Low Cost, High Speed, BiFET Dual Op Amp
• Manufacturer: Analog Devices

Specifications of AD712

• -3db Bandwidth: 4MHz
• Slew Rate: 20V/µs
• Vos: 300µV
• Ib: 25pA
• # Opamps Per Pkg: 2
• Input Noise (nv/rthz): 16nV/rtHz
• Vcc-vee: 9V to 36V
• Isy Per Amplifier: 2.8mA
• Packages: DIP,SOIC

AD712
DRIVING A LARGE CAPACITIVE LOAD
The circuit in Figure 46 uses a 100 Ω isolation resistor that enables
the amplifier to drive capacitive loads exceeding 1500 pF; the
resistor effectively isolates the high frequency feedback from
the load and stabilizes the circuit. Low frequency feedback is
returned to the amplifier summing junction via the low-pass filter
formed by the 100 Ω series resistor and the Load Capacitance C
Figure 47 shows a typical transient response for this connection.
TYPICAL CAPACITANCE
LIMIT FOR VARIOUS
LOAD RESISTORS
2kΩ
10kΩ
20Ω
R
1
INPUT
C
1500pF
1500pF
1000pF
1
4.99kΩ
Figure 46. Circuit for Driving a Large Capacitive Load
UP TO
30pF
+
–
AD712
+V
1/2
–V
4.99kΩ
IN
IN
0.1µF
+
–
0.1µF
–
+
100Ω
C1
R1
OUTPUT
Rev. H | Page 16 of 20
L
.
100
90
0%
10
Figure 47. Transient Response R
5V
L
= 2 kΩ, C
1µs
L
= 500 pF