clc410 National Semiconductor Corporation, clc410 Datasheet - Page 8

• Manufacturer Part Number: clc410
• Description: Fast Settling, Video Op Amp With Disable
• Manufacturer: National Semiconductor Corporation

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Application Division
Enable/Disable Operation
The CLC410 has an enable/disable feature that is useful for
conserving power and for multiplexing the outputs of several
amplifiers onto an analog bus ( Figure 3 ). Disabling an am-
plifier while not in use reduces power supply current and the
output and inverting input pins become a high impedance.
FIGURE 3.
(Continued)
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Pin 8, the DIS pin, can be driven from either open-collector
TTL or from 5V CMOS. A logic low disables the amplifier and
an internal 15k pull-up resistor ensures that the amplifier is
enabled if pin 8 is not connected ( Figure 5 ). Both TTL and 5V
CMOS logic are guaranteed to drive a high enough
high-level output voltage (V
enabled. Whichever type used, “break-before-make” opera-
tion should be established when outputs of several amplifi-
ers are connected together. This is important for avoiding
large, transient currents flowing between amplifiers when
two or more are simultaneously enabled. Typically, proper
operation is ensured if all the amplifiers are driven from the
same decoder integrated circuit because logic output rise
times tend to be longer than fall times. As a result, the
amplifier being disabled will reach the 2V threshold sooner
than the amplifier being enabled (see t
diagram).
FIGURE 4.
OH
) to ensure that the CLC410 is
D
of Figure 4 timing
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