OPA600BM BURR-BROWN [Burr-Brown Corporation], OPA600BM Datasheet - Page 7

• Manufacturer Part Number: OPA600BM
• Description: Fast-Settling Wideband OPERATIONAL AMPLIFIER
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

FIGURE 2. Capacitive Load Compensation and Response.
the OPA600 settling time to 1%, 0.1%, and 0.01%. The
best settling time is achieved in low closed-loop gain cir-
cuits.
Settling time is dependent upon compensation. Under-com-
pensation will result in small phase margin, overshoot or
instability. Over-compensation will result in poor settling
time.
Figure 1 shows the recommended compensation to yield the
specified settling time. Improved or optimum settling time
may be achieved by individually compensating each device
in the user’s circuit since individual devices vary slightly
from one to another, as do user’s circuits.
SLEW RATE
Slew rate is primarily an output, large signal parameter. It
has virtually no dependence upon the closed-loop gain or
small signal bandwidth. Slew rate is dependent upon com-
pensation and decreasing the compensation capacitor value
will increase the available slew rate as shown in the perfor-
mance curve.
The OPA600 slew rate may be increased by using an
alternate compensation as shown in Figure 3. The slew rate
will increase between 700 and 800V/ s typical, with 0.01%
settling time increasing to between 175 and 190ns typical,
and 0.1% settling time increasing to between 110 and 120ns
typical.
For alternate doublet compensation refer to Figure 3. For a
closed-loop gain equal to –1, delete C
series RC circuit (R = 22 , C = 0.01 F) Between pins 14
and 4. Make no connections to pins 11 and 5. Absolutely
minimize the capacitance to these pins. If a connector is used
for the OPA600, it is recommended that sockets for pins 11
and 5 be removed. For a PC board mount, it is recommended
that the PC board holes be overdrilled for pins 11 and 5 and
adjacent ground plane copper be removed. Effectively, this
compensation places the dominant pole at the input stage,
allowing the output stage to have no compensation and to
slew as fast as possible. Bandwidth and settling time are
impaired only slightly. For closed-loop gains other than –1,
different values of R and C may be required.
125
100
75
50
25
0
G
Capacitance
CLOSED LOOP
Load
2
Compensation Capacitance (pF)
= –1V/V
4
6
1
and C
Settling
Time
8
2
and add a
10
250
200
150
100
50
0
FIGURE 3. Amplifier Circuit for Increased Slew Rate.
OFFSET ADJUSTMENT
The offset voltage of the OPA600 may be adjusted to zero
by connecting a 5k
potentiometer in series with another 5k
pins 2 and 15, as shown in Figure 4. It is important that one
end of each of the two resistors be located very close to pins
2 and 15 to isolate and avoid loading these sensitive termi-
nals. The potentiometer should be a small noninductive type
with the wiper connected to the positive supply. The leads
connecting these components should be short, no longer
than 0.5-inch, to avoid stray capacitance and stray signal
pick-up. If the potentiometer must be located away from the
immediate vicinity of the OPA600, extreme care must be
observed with the sensitive leads. Locate the two 5k
resistors very close to pins 2 and 15.
Never connect +V
to eliminate the 5k
FIGURE 4. Offset Null Circuit.
NOTE: (1) 3pF typ. should match stray capacitance bewteen pin 3 and
NOTE: (1) 3pF typ. should match stray capacitance between pin 3
common.
e
IN
and common.
0.001µF
600
600
22
CC
directly to pin 2 or 15. Do not attempt
resistors because at extreme rotation,
resistor in series with a 10k
16
5k
3
16
14
3
4
–
+
–
+
600
OPA600
3pF
+
–
OPA600
15
10k
(1)
1
600
+V
3pF
2
CC
13
(1)
8
5k
12
6
–15VDC
–15VDC
Compensation
300
8
Capacitors
resistor between
Capacitance
Load
e
OUT
linear