SAFE OPERATING AREA (SOA)
The SOA curves combine the effect of all limits for
this Power Op Amp. For a given application, the
direction and magnitude of the output current
should be calculated or measured and checked
against the SOA curves. This is simple for resistive
loads but more complex for reactive and EMF
generating loads. The following guidelines may
save extensive analytical efforts:
1) Under transient conditions, capacitive and
dynamic* loads up to the following maximums are
safe:
•If the inductive load is driven near steady state
conditions, allowing the output voltage to drop
more than 8V below the supply rail with I
LIM = 5A,
or 17V below the supply rail with I
LIM = 2A while the
amplifier is current limiting, the inductor should be
capacitively coupled or the current limit must be
lowered to meet SOA criteria.
TPA02/02A Rev. A Sept. 2006
DISCUSSION OF PERFORMANCE
These simplified limits may be exceed with
further analysis using the operating conditions
for a specific application.
2. The amplifier can handle any EMF generating
or reactive load and short circuits to the supply
rails or shorts to common if the current limits are
set as follows at Tc = 85°C.
CURRENT LIMIT
Proper operation requires the use of two current
limit resistors, connected as shown in the
external connections diagram. The minimum
value for R
CL is 0.12 ohm, however for optimum
reliability it should be set as high as possible.
DEVICE MOUNTING
The case (mounting flange) is electrically
isolated and should be mounted directly to a
heatsink with thermal compound. Screws with
Belville spring washers are recommended to
maintain positive clamping pressure on heatsink
mounting surfaces. Long periods of thermal
cycling can loosen mounting screws and
increase thermal resistance.
Since the case is electrically isolated (floating)
with respect to the internal circuits, it is
recommended to connect it to common or other
convenient AC ground potential.
Capacitive Load
Inductive Load
±V
s
I
LIM = 2A
I
LIM = 5A
I
LIM = 2A
I
LIM= 5A
18V
2mF
0.7mF
0.2H
10mH
15V
10mF
2.2mF
0.7H
25mH
10V
25mF
10mF
5H
50mH
Short to ±V
S
Short to
±V
s
C,L or EMF Load
Common
18V
0.5A
1.7A
15V
0.7A
2.8A
10V
1.6A
4.2A
5.0
4.0
3.0
2.0
1.5
1.0
0.7
0.5
0.3
0.2
2
3
5
7
10
15
20
25 30
40
SUPPLY TO OUTPUT DIFFERENTIAL VOLTAGE (V)
T
C
= 1
25 o
C
T
C
= 1
00 o
C
T
C
= 70
oC
T
C
= 2
5 o
C
TH
ER
MA
L
t =
5m
s
SE
CO
ND
BR
EA
KD
OW
N
SOA
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