CMOS Dual operational amplifier
ELM854xx
■Note
1) Common-mode input voltage range
ELM854xx common mode input voltage range is fixed under the condition of CMRR≥45dB; ELM854xx
is able to accept the input above its specification if the degradation of CMRR is not considered. Even if the
input voltage exceeds either positive or negative power voltage, troubles such as reverse of output will not
occur.
As maximum absolute rating, the input voltage is possible within (Vss-0.3)V to (Vdd+0.3)V.
2) Operation from single power source
ELM854xx is designed to be most suitable for single power source; therefore, ELM854xx is able to share
power supply with logic circuit one. Meanwhile, ELM832BW can also operate from double power sources.
To protect power supplies of ELM854xx and logic circuit from noise, please separate wire from power
supply and use decoupling (bypass) capacitor. Using the capacitor can improve PSRR characteristics,
especially on 10kHz to 100kHz or more.
3) Feedback
When OP-AMP circuit is used with feedback resistor, oscillation may happen in the circuit with loop-gain
like unity gain follower.
a) When large feedback resistance is used, the phase margin is decreased by its combination with the
parasitic capacitance of the input part of OP-AMP. In this situation, please connect small capacitor parallelly
with feedback resistor as shown in fig-1.
b) For capacitive load, external resistor in series connection will be effective as shown in fig-2. (R=300 to
500Ω)
c) Being used as an unity gain follow, ELM854xx is able to drive capacitive load of 100pF directly without
oscillation.
a) fig-1
b) fig-2
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ᎶᎼᎻ
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፴
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4) Unused Amplifier
Two amplifiers will consume power even if only one amplifier is used.
In order to minimize power consumption by the unused amplifier, ELM recommends to connect this
amplifier as voltage follower circuit and the input terminal (IN+) to Vdd.
9 - 4
ELM-TECH [ ELM Technology Corporation ]
