EPC134 datasheet(7/11 Pages) EPC

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epc134/epc135/epc136/epc137/epc138/epc139

Functional Description

Power-up Sequence

If VDD reaches VPOR, the startup sequence is initiated. After the time tDEL, the photo diode bias circuit is enabled. Thus, a current generated by

light on the photo diode flows into the pin PD. After the time tINIT, the device is ready to receive AC light pulses.

POR

INIT

Startup

Period

Ready

Out

false pulses may occur

Power-up sequence

Power-down Sequence

When VDD goes down, the device is turned off when V DD is below VPOR minus VIPOR.

POR -

IPOR

OFF

PD bias

Power-down sequence

Light Pulse Reception

A light pulse on the photo diode generates a current puls into the pin PD of the device. If the current pulse exceeds the threshold I PD, an output

pulse is generated. The length of the output pulse is given by tOut. After a waiting time given by tREC, the next light pulse can be sent. If the

waiting time is too short, the device is not ready to receive the next pulse. Thus, no output pulse is appears at pin OUT.

IR LED Pulse

IR LED

PD Signal

Out Signal

OUT

REC

OUT

2nd pulse indicates light

reserve threshold triggered

Light pulse reception

Characteristics subject to change without notice

Datasheet epc13x digital - V2.1

EPC134 Datasheet(PDF) 7 Page - Espros Photonics corp