LMV324M National Semiconductor, LMV324M Datasheet - Page 20

• Manufacturer Part Number: LMV324M
• Description: Operational Amplifier (Op-Amp) IC
• Manufacturer: National Semiconductor

Specifications of LMV324M

• No. Of Amplifiers: 1
• Slew Rate: 1V/µs
• No. Of Pins: 14
• Amplifier Type: Operational
• Mounting Type: Surface Mount
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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Application Notes
4.6 CURRENT SOURCE AND SINK
The LMV321/358/324 can be used in feedback loops which
regulate the current in external PNP transistors to provide
current sources or in external NPN transistors to provide
current sinks.
4.6.1 Fixed Current Source
A multiple fixed current source is show in Figure 20. A
voltage (V
voltage divider (R
cause the voltage drop across R
controls the emitter current of transistor Q
the base current of Q
is available out of the collector of Q
Large input resistors can be used to reduce current loss and
a Darlington connection can be used to reduce errors due to
the β of Q
The resistor, R
Q
2
either above or below the 1mA reference value.
REF
1
FIGURE 19. Squarewave Generator
.
FIGURE 20. Fixed Current Source
= 2V) is established across resistor R
2
, can be used to scale the collector current of
3
and R
1
and Q
4
). Negative feedback is used to
2
, essentially this same current
(Continued)
1
to be equal to V
1
.
1
and if we neglect
REF
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3
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by the
. This
20
4.6.2 High Compliance Current Sink
A current sink circuit is shown in Figure 21. The circuit
requires only one resistor (R
rent which is directly proportional to this resistor value.
4.7 POWER AMPLIFIER
A power amplifier is illustrated in Figure 22. This circuit can
provide a higher output current because a transistor follower
is added to the output of the op amp.
4.8 LED DRIVER
The LMV321/358/324 can be used to drive an LED as shown
in Figure 23.
FIGURE 21. High Compliance Current Sink
FIGURE 22. Power Amplifier
FIGURE 23. LED Driver
E
) and supplies an output cur-
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