EPC110 Datasheet, PDF (7/27 Pages) Espros Photonics corp – Fully integrated configurable light barrier driver & receiver

epc110
VDD
VDD
IN1
µC ^IN2
EN
OUT _{OUT GND}
R
Stab
VDD
epc100
VDD33
OUTN
OUTH
EN
LED
PD _GND
R_LED
C1
GND
Figure 4: Principle of controlled light barrier application using a micro-controller
The photo diode current is compared to two threshold levels. The result OUTH from the higher comparison level may be used to detect the
light reserve.
Evaluation of a single light pulse
The photodiode is operated against ground and is reverse biased at a constant voltage of 1.2V. The input impedance of pin PD is kept low
(<1 kOhm @ 100kHz) in order to minimize the influence of the parasitic capacitance of the photodiode. To ensure proper operation under high
ambient-light conditions, the photo diode DC current can be up to 2 mA.
The resulting current from the light pulses are converted to a voltage, filtered, amplified and compared to two different threshold levels. The
lower threshold SENSN (input related 60nA typical) is used for the detection of the signal, the higher threshold SENSH (input related to
96nA typical) is used to provide an output when a certain signal reserve is achieved.
To detect the received light pulse properly, the given threshold must be at least five times higher than the rms value of the noise floor
generated by the circuitry without AC_Ali_Ngh_et s_pti_cm₁u₀la₀tio_lin_g._{ht curtain Transmitter}
LST
The comparator results_Fa_ilere_: digitally filtered and output at pin OUT and OUTH.
The parameter TPER ^Td^he^isf^di^on^ce^ums^ent^th^ise^cons^fic^deaⁿn^tial p^ane^dr^pi^ro^otd^ectein^{d by}th^lawe^ans^dta^intn^erd^naa^tiolo^nan^{l t}e^radl^ei^sg^. h^{It m}t ^ub^staⁿr^or^t i^be^er^sha^owpⁿp^toli^acⁿa^{y t}t^hiⁱo^rdn^parb^tyuⁿt^or h^bea^cs^opiea^dlsⁱⁿo^anya^fn^ormim^withp^oa^utc^ot^ur t^wo^ritteth^{n p}e^ermsⁱe^sst^iotⁿli^.ng time of the
receiver in the controlled mode application. It this case it has to be set corresponding to the scan period. Refer to the description of the TPER
command.
For each single light pulse, received and detected by the photodiode, the threshold levels for output OUTN and for output OUTH can be set by
programming (parameter SENSN resp. SENSH). They are processed according to the following principle to propagate the output signals
OUTN and OUTH resp. OUTNINT and OUTHINT. As far the received light pulse signal exceeds the corresponding threshold level, the pulse will
be recognized as a valid pulse and the detection circuit sets the appropriate output signal OUTN INT or OUTHINT.
I_PD
Threshold levels:
Light reserve OUTH
Signal output OUTN
Light pulse detection
I_PD
Light reserve detection
t
t
OUTN_INT
t
t
OUTH_INT
t
t
Figure 5: Pulse evaluation
© 2011 ESPROS Photonics Corporation
7
Characteristics subject to change without notice
Datasheet epc110 - V2.1
www.espros.ch