LM8261M5/NOPB National Semiconductor, LM8261M5/NOPB Datasheet - Page 17

• Manufacturer Part Number: LM8261M5/NOPB
• Description: IC OP AMP HI OUT R-R SOT23-5
• Manufacturer: National Semiconductor

Specifications of LM8261M5/NOPB

• Amplifier Type: General Purpose
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 15 V/µs
• Gain Bandwidth Product: 24MHz
• Current - Input Bias: 1.05µA
• Voltage - Input Offset: 700µV
• Current - Supply: 1.3mA
• Current - Output / Channel: 100mA
• Voltage - Supply, Single/dual (±): 2.5 V ~ 30 V, ±1.25 V ~ 15 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Other names: LM8261M5; LM8261M5TR

TFT APPLICATIONS
Figure 8
is used as a buffer amplifier for the V
a TFT LCD flat panel:
Figure 9
when used as a V
application, the Op Amp loop will try and maintain its output
voltage based on the voltage on its non-inverting input
(V
load. As long as this load current is within the range tolerable
by the LM8261 (45mA sourcing and 65mA sinking for ±5V
supplies), the output will settle to its final value within less than
2µs.
OUTPUT SHORT CIRCUIT CURRENT AND DISSIPATION
ISSUES
The LM8261 output stage is designed for maximum output
current capability. Even though momentary output shorts to
ground and either supply can be tolerated at all operating
voltages, longer lasting short conditions can cause the junc-
tion temperature to rise beyond the absolute maximum rating
of the device, especially at higher supply voltage conditions.
Below supply voltage of 6V, output short circuit condition can
be tolerated indefinitely.
With the Op Amp tied to a load, the device power dissipation
consists of the quiescent power due to the supply current flow
into the device, in addition to power dissipation due to the load
current. The load portion of the power itself could include an
average value (due to a DC load current) and an AC compo-
nent. DC load current would flow if there is an output voltage
REF
FIGURE 9. V
) despite the current injected into the TFT simulated
below, shows a typical application where the LM8261
shows the time domain response of the amplifier
COM
COM
buffer/driver with V
driver performance scope photo
COM
FIGURE 8. V
REF
signal employed in
10108465
at ground. In this
COM
Driver Application Schematic
17
offset, or the output AC average current is non-zero, or if the
Op Amp operates in a single supply application where the
output is maintained somewhere in the range of linear oper-
ation. Therefore:
where:
I
V
I
V
V
Table 1
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:
P
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 (> 4.7µF). The large
S
O
P
P
P
P
S
O
R
AC
: Supply Current
: Average load current
TOTAL
Q
DC
AC
: Total Supply Voltage (V
: Average Output Voltage
: V
= (46.9 x 10
= I
∼
= See Table 1 below
+
= I
0.01µF) placed very close to the supply lead in addition
S
for sourcing and V
50.7 x 10
Sinusoidal
below shows the maximum AC component of the load
O
= P
· V
· (V
S
S
Q
2
R
Stage for Standard Waveforms
/ R
+ P
- V
−3
−3
L
DC
. For example, with ±15V supplies, a 600Ω
) · [30
O
)
+ P
P
2
AC
/600]= 70.4mW
AC
−
46.9 x 10
Triangular
for sinking current
+
(W.Ω/V
- V
10108461
−
)
Op Amp Quiescent Power
−3
2
)
S
2
/ R
L
. To figure out the
62.5 x 10
DC Load Power
AC Load Power
Square
Dissipation
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−3