epc120
Fully integrated Light-Barrier Chips with 2-Wire Bus Interface
General Description
The epc120 is a general purpose, fully integrated self-contained
CMOS circuit to be used in light-barrier applications. The chips
contain a controller which drives an LED, typically an IR-LED. The
LED is used in a pulsed mode to increase the signal-to-noise ratio
even when there is very strong sunlight biasing the photo diode.
It contains also a high sensitive photo diode amplifier and a signal
conditioning circuitry to cancel unwanted environmental light including
strong sunlight and pulsed light sources. The receiver is built around
a synchronous demodulator circuitry. Two output signals with a
different threshold level are implemented in order to trigger the light
barriers output or to indicate light reserve.
The chips also include a power supply circuitry to establish all
internally required voltages from the 2-wire bus.
They contain a 2-wire communication interface which is capable to
operate as many as 1023 devices on a 2-wire bus at a speed of up to
2MBit/s over the power supply. This feature allows to design of a
distributed light barrier system.
Features
Fully integrated light barrier chip
Needs just a photo diode and an LED with an LED driver
Configurable
High speed 2-wire bus
Integrated clock generator
CSP10 package with very small footprint or
standard QFN16 package available
Versions without 2-wire bus interface available (epc11x family)
Applications
Light barriers ranging from millimeters to tens of meters
Smoke detectors
Liquid detectors
Functional Block Diagram
VDD
V
LED
2-wire COM
Interface
Parameter
Memory
LED
SCK
LED
VDD33
Voltage Regulator
Processor
VDD18
SPI
Controller
Signal
Processor
PD
f
D1
GND
CS
SI
EN
SO
© 2011 ESPROS Photonics Corporation
Characteristics subject to change without notice
1
Datasheet epc12x - V2.1
www.espros.ch
EPC [ ESPROS PHOTONICS CORP ]
