lm7322mmx National Semiconductor Corporation, lm7322mmx Datasheet - Page 20

• Manufacturer Part Number: lm7322mmx
• Description: Lm7321 Single/ Lm7322 Dual Rail-to-rail Input/output, ?15v, High Output Current And Unlimited Capacitive Load Operational Amplifier
• Manufacturer: National Semiconductor Corporation

www.national.com
Table 1 below shows the maximum AC component of the load
power dissipated by the op amp for standard Sinusoidal, Tri-
angular, and Square Waveforms:
TABLE 1. Normalized AC Power Dissipated in the Output
The table entries are normalized to V
AC load current component of power dissipation, simply mul-
tiply the table entry corresponding to the output waveform by
the factor V
load, and triangular waveform power dissipation in the output
stage is calculated as:
The maximum power dissipation allowed at a certain temper-
ature is a function of maximum die junction temperature (T
(MAX)
resistance from junction to ambient, θ
For the LM7321/LM7322, the maximum junction temperature
allowed is 150°C at which no power dissipation is allowed.
The power capability at 25°C is given by the following calcu-
lations:
For MSOP package:
For SOIC package:
Similarly, the power capability at 125°C is given by:
For MSOP package:
For SOIC package:
Figure 11 shows the power capability vs. temperature for
MSOP and SOIC packages. The area under the maximum
thermal capability line is the operating area for the device.
When the device works in the operating area where P
less than P
below 150°C. If the intersection of ambient temperature and
package power is above the maximum thermal capability line,
the junction temperature will exceed 150°C and this should
be strictly prohibited.
50.7 x 10
) allowed, ambient temperature T
Sinusoidal
P
AC
D(MAX)
S
2
= (46.9 x 10−
Stage for Standard Waveforms
−3
/R
L
, the device junction temperature will remain
. For example, with ±12V supplies, a 600Ω
P
46.9 x 10
AC
Triangular
3
) · [242/600] = 45.0 mW
(W.Ω/V
−3
2
)
A
S
JA
, and package thermal
2
/R
.
L
. To figure out the
62.5 x 10
Square
TOTAL
−3
is
J
20
When high power is required and ambient temperature can't
be reduced, providing air flow is an effective approach to re-
duce thermal resistance therefore to improve power capabil-
ity.
Other Application Hints
The use of supply decoupling is mandatory in most applica-
tions. As with most relatively high speed/high output current
Op Amps, best results are achieved when each supply line is
decoupled with two capacitors; a small value ceramic capac-
itor (
to a large value Tantalum or Aluminum (> 4.7 μF). The large
capacitor can be shared by more than one device if neces-
sary. The small ceramic capacitor maintains low supply
impedance at high frequencies while the large capacitor will
act as the charge "bucket" for fast load current spikes at the
op amp output. The combination of these capacitors will pro-
vide supply decoupling and will help keep the op amp oscil-
lation free under any load.
SIMILAR HIGH OUTPUT DEVICES
The LM7332 is a dual rail-to-rail amplifier with a slightly lower
GBW capable of sinking and sourcing 100 mA. It is available
in SOIC and MSOP packages.
The LM4562 is dual op amp with very low noise and 0.7 mV
voltage offset.
The LME49870 and LME49860 are single and dual low noise
amplifiers that can work from ±22 volt supplies.
OTHER HIGH PERFORMANCE SOT-23 AMPLIERS
The LM7341 is a 4 MHz rail-to-rail input and output part that
requires only 0.6 mA to operate, and can drive unlimited ca-
pacitive load. It has a voltage gain of 97 dB, a CMRR of 93
dB, and a PSRR of 104 dB.
The LM6211 is a 20 MHz part with CMOS input, which runs
on ±12 volt or 24 volt single supplies. It has rail-to-rail output
and low noise.
The LM7121 has a gain bandwidth of 235 MHz.
Detailed information on these parts can be found at
www.national.com.
∼
FIGURE 11. Power Capability vs. Temperature
0.01 μF) placed very close to the supply lead in addition
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