EPC111 EPC [Espros Photonics corp], EPC111 Datasheet - Page 9

• Manufacturer Part Number: EPC111
• Description: Fully integrated standalone light barrier driver & receiver
• Manufacturer: EPC [Espros Photonics corp]

Applications
Long range light barrier application
Figure 10 shows the epc111 as an example in a long range light barrier application with minimal part count. The LED flashes according to the
description of the previous chapter. Light of the LED is passing either direct, reflected from a reflecting object or a retro reflector to the photo
diode PD. If the received light fulfills the criteria according to the description in the previous chapter, the output signals OUTN and OUTH are
set.
The epc111 device is designed to operate at 3.3V power supply (VDD and VDD33).
LED Driver:
The output LED of the epc111 to drive the LED driver circuit is a current source capable to drive typically 1mA. For a high performance long
range light barrier (>8m), an LED peak current of up to 1.5A is needed. To generate such a high LED current, an external driver circuit is
necessary. The circuitry in Figure 10 is a simple implementation of such a driver circuit. The darlington circuit with T2 and T3 and R2 and R3
does the job. In order to avoid interference on the supply voltage, the supply is isolated (filtered) with R1 and C1. The high peak LED pulse
current is delivered by the capacitor C1, which itself is charged by R1. Make sure, that there is no coupling of the high LED current to the
ground of the epc111 or to the cathode of the photo diode. This driver circuit operates with a VDD
Notice:
The schematic is for illustrating the basic circuit idea only. For the real built up the designer has to take all other additional influence factors in
consideration too e.g. design rules, power rating, heat dissipation, ...
© 2011 ESPROS Photonics Corporation
Characteristics subject to change without notice
PD
epc300
C2
C4 100nF
C5 4.7nF
Marked conductors must be short and low ohmic
The epc111 device with its very sensitive input PD needs a well decoupled power supply
C3 100nF
C2 1μF
PD
VDD33
VDD18
Figure 10: Long range light barrier application with minimal part count
epc111
+3.3V
VDD
GND
GND
OUTN
OUTH
LED
OUTN
R4
10k
R5
3k6
9
R6
12k
R7
4k7
T1
BC846
OUTH
R8
10k
IR LED
TSML1000
T2
BC846
LED
R2
1k
in a range of 10 to 30 VDC.
.
T3
BCP56
R3
1R2
VDD
Datasheet epc111_112 - V2.2
LED
= +24V
C1
47μF
Low ESR
R1
100R
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epc111/112
www.espros.ch