Data Sheet

Detailed Description
The MAX30105 is a complete particle detection sensor
system solution module. The MAX30105 maintains a very
small solution size without sacrificing optical/electrical
performance. Minimal external hardware components are
required for integration into a smoke detection system.
The MAX30105 is fully adjustable through software registers,
and the digital output data can be stored in a 32-deep
FIFO within the IC. The FIFO allows the MAX30105 to be
connected to a microcontroller or processor on a shared
bus, where the data is not being read continuously from
the MAX30105’s registers.
Particle-Sensing Subsystem
The particle-sensing subsystem contains ambient light
cancellation (ALC), a continuous-time sigma-delta ADC,
and proprietary discrete time filter. The ALC has an internal
Track/Hold circuit to cancel ambient light and increase the
effective dynamic range. The particle-sensing ADC has
a programmable full-scale range from 2µA to 16µA. The
ALC can cancel up to 200µA of ambient current.
The internal ADC is a continuous time oversampling
sigma-delta converter with 18-bit resolution. The ADC
sampling rate is 10.24MHz. The ADC output data rate
can be programmed from 50sps (samples per second) to
3200sps.
Temperature Sensor
The MAX30105 has an on-chip temperature sensor for
calibrating the temperature dependence of the particle-
sensing
subsystem. The temperature sensor has an
inherent resolution 0.0625°C.
LED Driver
The MAX30105 integrates red, green, and IR LED drivers
to modulate LED pulses for particle-sensing measurements.
The LED current can be programmed from 0 to 50mA
with proper supply voltage. The LED pulse width can be
programmed from 69µs to 411µs to allow the algorithm to
optimize particle-sensing accuracy and power consumption
based on use cases.
Proximity Function
When the particle-sensing function is initiated (by writing
the MODE register), the IR LED is activated in proximity
mode with a drive current set by the PILOT_PA register.
When an object is detected by exceeding the IR ADC
count threshold (set in the PROX_INT_THRESH regis-
ter), the part transitions automatically to the normal parti-
cle-sensing Mode. To reenter proximity mode, the MODE
register must be rewritten (even if the value is the same).
The proximity function can be disabled by resetting
PROX_INT_EN to 0. In this case, the particle-sensing
mode begins immediately.
880nm660nm
ADC
AMBIENT LIGHT
CANCELLATION
ANALOG
ADC
DIE TEMP
OSCILLATOR
DIGITAL
FILTER
DIGITAL
DATA
REGISTER
LED DRIVERS
I
2
C
COMMUNICATION
INT
SDA
SCL
V
DD
V
LED+
IR_DRVR_DRV
GND
PGND
RED IR
VISIBLE+IR
MAX30105
GREEN
527nm
G_DRV
www.maximintegrated.com
Maxim Integrated │ 10
MAX30105 High-Sensitivity Optical Sensor
for Smoke Detection Applications
Functional Diagram