RE46C420/1/2
Multicriteria Smoke Detector Companion IC with Dual
Photoelectric and CO Sensing
Features
General Description
• Low Quiescent Current
The RE46C420/1/2 device is a low-power smoke
detector companion IC. It provides all of the analog,
• Operation from Two AA Batteries or a Single
Lithium Battery
interface and power regulation functions for
a
microcontroller-based multicriteria smoke detector. It is
intended for use in 3V and 9V battery applications. It
features an integrating photo amplifier to interface with
a photoelectric smoke chamber, two independently
controlled programmable LED drivers, an operational
amplifier with 10 kHz gain-bandwidth product and
rail-to-rail inputs and output, to interface with a
two-terminal CO sensor, a boost converter and driver
circuit suitable for driving a piezoelectric horn, an
interconnect output with a 5 mA current source for
signaling an alarm condition to interconnected units, a
low battery detection circuit and a 3.3V regulator.
• 4V, 5.2V, 8.5V, 10V, 11.5V, 17V Boost Converter
• Piezoelectric Horn Driver
• 3.3V Regulator
• Dual Independently-Controlled LED Drivers with
Programmable Current up to 200 mA
• Dual-Input Programmable Gain Integrating
Operational Amplifier with Effective
Transimpedance higher than 20 M at 100 μs
• Internal Operational Amplifier for use with CO or
Toxic Gas Sensor
- Rail-to-Rail Inputs and Output
- Unity Gain Stable
Differences between the devices:
• RE46C420:
- 10 kHz Gain Bandwidth Product
• Buffered Internal CO Reference
- One integrating photo amplifier
- CO circuitry
• Analog Buffer for Sensing Multiple Internal
Voltages
• RE46C421:
• Alarm Interconnect
- Dual integrating photo amplifiers
- No CO circuitry
• Serial Peripheral Interface (SPI) Controlled
• Packaging: 4 x 4 mm, 28-Lead VQFN (RE46C420
and RE46C421), 5 x 5 mm, 32-Lead VQFN
(RE46C422 only)
• RE46C422:
- Dual integrating photo amplifiers
- CO circuitry
The RE46C420/1/2 allows the microcontroller unit to
access and manage all of the parameters which set the
output voltage signal levels of the RE46C420/1/2
device, such as the LED current, amplifier gain and the
integration time. All of these parameters, including the
enabling of various functions, can be set through the
SPI port.
2021-2023 Microchip Technology Inc. and its subsidiaries
DS20006592C-page 1