Description
The Microchip RE46C400/1 is a low-power smoke
detector MCU companion IC intended for panel-based
applications. It provides all of the analog, interface and
power regulation functions for a microcontroller-(MCU)
based multicriteria smoke detector. The RE46C400/1
can be powered from a constant current typically used
in panel-based applications. The product features an
integrating photo amplifier to interface with a
photoelectric smoke chamber, two independently
controlled programmable LED drivers, an op amp with
10 kHz Gain Bandwidth Product and rail-to-rail inputs
and output to interface with a two terminal CO sensor,
an analog buffer circuit (ABUF) for monitoring system
voltages and a 3.3V regulator. The RE46C401 does not
include the CO circuitry.
The RE46C400/1 allows the MCU to control all the
parameters which set the operating conditions of the
RE46C400/1 such as LED current, amplifier gain and
integration time. All of these parameters including the
enabling of various functions will be set via the SPI port.

Features
• Low Quiescent Current
• 3.3V Regulator
• Dual Independently Controlled LED Drivers with
Programmable Current up to 200 mA
• Single Programmable Gain Integrating Op Amp
with Effective Transimpedance > 20 M at 100 μs
• Internal Op Amp for use with CO or Toxic Gas Sensor
- Rail-to-Rail Inputs and Output
- Unity Gain Stable
- 10 kHz Gain Bandwidth Product
• Buffered Internal CO reference
• Voltage Monitoring Circuit (ABUF)
• Watchdog Timer
• SPI Controlled
• Powered from a Current Source