OP450GRU AD [Analog Devices], OP450GRU Datasheet - Page 12

• Manufacturer Part Number: OP450GRU
• Description: CMOS Single-Supply Rail-to-Rail Input/Output Operational Amplifiers
• Manufacturer: AD [Analog Devices]

OP250/OP450
be connected from the output to ground in parallel with the ca-
pacitive load as shown in Figure 33. The proper snubber net-
work on the output can significantly reduce output overshoot,
although it will not increase the bandwidth. Table I shows some
snubber network values for a given capacitive load. In practice,
these values are best determined empirically based on the exact
capacitive load for the application.
Load Capacitance (C
1 nF
10 nF
100 nF
Figure 34 shows the output of an OP250 in a unity gain configu-
ration with a 1 nF capacitive load. Figure 35 shows the improve-
ment in the output response with the snubber network added.
Figure 34. Output of OP250 without Snubber Network
Figure 33. Schematic for Using a Snubber Network
Table I. Snubber Network for Large Capacitive Loads
Figure 35. Output of OP250 with Snubber Network
100mV p-p
V
V
IN
IN
= 100mV
50mV
50mV
L
)
p-p
OP250
@ 100kHz
+5V
C
R
V
IN
L
L
Snubber Network (RS, CS)
60 , 30 nF
20 , 1 F
3 , 10 F
= 1nF
= 10k
= 100mV
R
5
C
1 F
S
p-p
S
C
R
@ 100kHz
2µs
2µs
L
L
= 1nF
= 10k
C
47nF
L
V
OUT
–12–
For more information on methods to drive a capacitive load with
an op amp, please refer to the Ask the Applications Engineer ar-
ticle in Analog Dialogue, Vol. 31, Number 2, 1997.
Single Supply Differential Line Driver
Figure 36 shows a single supply differential line driver circuit
that can drive a 600
design uses an OP450 to mimic the performance of a fully bal-
anced transformer based solution. However, this design occupies
much less board space while maintaining low distortion and can
operate down to dc. Like the transformer based design, either
output can be shorted to ground for unbalanced line driver ap-
plications without changing the circuit gain of 1.
Figure 36. A Low Noise, Single Supply Differential Line Driver
R8 and R9 set up the common mode output voltage equal to
half of the supply voltage. C1 is used to couple the input signal
and can be omitted if the input’s dc voltage is equal to half of
the supply voltage.
The circuit can also be configured to provide additional gain if
desired. The gain of the circuit is:
Where: V
R2 = R7 = R10 = R11 and,
R3 = R6 = R12 = R13
Multimedia Headphone Amplifier
Because of its large output drive, the OP250 makes an excellent
headphone amplifier, as illustrated in Figure 37. Its low supply
operation and rail-to-rail inputs and outputs can maximize out-
put signal swing on a single +5 V supply. In Figure 37, the am-
plifier inputs are biased halfway between the supply voltages,
which in this application is 2.5 V. A 10 F capacitor prevents
power supply noise from contaminating the audio signal.
V
IN
A1, A2 = 1/2 OP250
GAIN = R3
SET: R7, R10, R11 = R2
SET: R6, R12, R13 = R3
22 F
C1
R2
OUT
2
3
+5V
A1
= V
10k
10k
10k
R1
O1
R10
1
R2
– V
load with less than 0.1% distortion. The
A
V
O2
,
R11
10k
R7
10k
2
3
5
6
V
V
OUT
10k
A2
A2
R3
IN
7
10k
R12
+12V
10k
R13
1
7
A1
R
R
100k
10k
6
5
3
2
R6
R9
+5V
R14
50
50
R5
R8
100k
1 F
C2
47 F
47µF
C3
600
C4
REV. 0
R
L
V
V
(5)
O2
O1