Datasheet

LMV321-N, LMV321-N-Q1, LMV358-N, LMV358-N-Q1
LMV324-N, LMV324-N-Q1
SNOS012I –AUGUST 2000–REVISED FEBRUARY 2013 www.ti.com
Figure 67 is a squarewave generator with the same path for charging and discharging the capacitor.
Figure 67. Squarewave Generator
CURRENT SOURCE AND SINK
The LMV321-N/LMV358-N/LMV324-N 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.
Fixed Current Source
A multiple fixed current source is shown in Figure 68. A voltage (V
REF
= 2V) is established across resistor R
3
by
the voltage divider (R
3
and R
4
). Negative feedback is used to cause the voltage drop across R
1
to be equal to
V
REF
. This controls the emitter current of transistor Q
1
and if we neglect the base current of Q
1
and Q
2
,
essentially this same current is available out of the collector of Q
1
.
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
1
.
The resistor, R
2
, can be used to scale the collector current of Q
2
either above or below the 1 mA reference value.
Figure 68. Fixed Current Source
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