Archived by Freescale Semiconductor, Inc., 2009
Rev 2, 05/2005
Micro-Power Comparator plus
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 and VDD.
The chip requires one external component. A 3.9 MΩ ±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.
Line-Powered Smoke Detectors
CO Detector and Micro Interface
• Operating Voltage Range: 3.5 to 14 V
• Operating Temperature Range: -30° to 70°C
• Input Current (IN + Pin): ±1 pA @ 25°C (DIP Only)
• Quiescent Current: 10 μA @ 25°C
• Electrostatic Discharge (ESD) Protection Circuitry on All Pins
-30° to 70°C
PLUS VOLTAGE FOLLOWER
15 IN +
13 Buff OUT
9 OUT C2
Figure 1. Pin Connections
© Freescale Semiconductor, Inc., 2005. All rights reserved.