The MC14578 is an analog building block consisting of a very–high input impedance comparator. The voltage follower allows monitoring the noninverting input of the comparator without loading.
Four enhancement–mode MOSFETs are also included on chip. These FETs can be externally configured as open–drain or totem–pole outputs. The drains have on–chip static–protecting diodes. Therefore, the output voltage must be maintained between VSS
The chip requires one external component. A 3.9 M-ohm ±10% resistor must be connected from the Rbias
pin to VDD
. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications.
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