Application Hints
(Continued)
COMPENSATION AND OUTPUT CLAMPING
The LM363 is internally compensated for unity feedback
from output to sense. Increasing gain with external dividers
will decrease the bandwidth and increase stability margin.
Without external compensation, the amplifier can stably
drive capacitive loads up to 400 pF. When used as an op
amp (sense and reference pins grounded, feedback to in-
verting input), the LM363 is stable for gains of 100 or more.
For greater stability, the device may be over-compensated
as in Figure 6. Tables I and II depict suggested compensa-
tion components along with the resulting changes in large
and small signal bandwidth for the 8-pin and 16-pin pack-
ages, respectively.
Note that the RC network from pin 8 of the 8-pin device to
ground has a large effect on power bandwidth, especially at
low gains. The Miller capacitance utilized for overcompen-
sating the 16-pin device permits higher slew rate and larger
load capacitance for the same bandwidth, and is preferred
when bandwidth must be greatly reduced (e.g., to reduce
output noise).
Heavy Miller overcompensation on the 16-pin package can
degrade AC PSRR. A large capacitor between pins 15 and
16 couples transients on the positive supply to the output
buffer. Since the amplifier bandwidth is severely rolled off it
cannot keep the output at the correct state at moderate
frequencies. Hence, for good PSRR, either keep the Miller
capacitance under 1000 pF or use the pin 15-to-ground
compensation shown in Table I.
TL/H/5609–14
FIGURE 6. Overcompensation
TABLE I. Overcompensation on 8-Pin Package
Small Signal
3 dB
Bandwidth
(kHz)
Power
Bandwidth
(
g
10V Swing)
(Hz)
Maximum
Capacitive
Load
(pF)
Compensation Network
(Pin 8 to Ground)
2
Gain
D
125
95
45
10
1
100k
15k
1.8k
200
20
400
600
800
1000
*
1000
*
400
900
1200
1600
*
2000
*
400
900
1200
1600
*
2000
*
100 pF, 15k
1000 pF, 5k
m
F,500
X
0.1
m
F
D
100 pF, 15k
1000 pF, 5k
0.01
m
F, 500
X
0.1
m
F
D
100 pF, 15k
1000 pF, 5k
0.01
m
F, 500
X
0.1
m
F
500
240
170
80
20
2
100k
15k
1.8k
200
20
100
240
170
90
20
2
100k
15k
1.8k
200
20
10
*
Also stable for C
L
t
0.05
m
F
2
Pin 15 to ground on 16-pin package
TABLE II. Overcompensation on 16-Pin Package
Compensation
Capacitor
(Pin 15 to 16)
Small Signal
3 dB
Bandwidth
(Hz)
Power
Bandwidth
(
g
10V Swing)
(Hz)
Maximum
Capacitive
Load
(pF)
1000
*
2000
*
2500
*
3000
*
3000
*
900
1600
2000
*
2000
*
2000
*
600
1100
1600
2000
*
2000
*
Gain
D
45k
16k
2.5k
250
25
45k
16k
2.5k
250
25
10 pF
100 pF
1000 pF
0.01
m
F
D
10 pF
100 pF
1000 pF
0.01
m
F
D
10 pF
100 pF
1000 pF
0.01
m
F
1000
140k
50k
7.5k
750
75
100k
50k
7.5k
750
75
100
180k
60k
9k
900
90
90k
50k
9k
900
90
10
*
Also stable for C
L
t
0.05
m
F
12