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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.
V
V
POR
DD
Startup
Period
Ready
t
INIT
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
.
V
V
V
DD
POR - IPOR
PD bias
t
OFF
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.
T
IR LED
IR LED Pulse
T
PD
PD Signal
Out Signal
2nd pulse indicates light
reserve threshold triggered
t
t
t
OUT
OUT
OUT
t
REC
Light pulse reception
© 2011 ESPROS Photonics Corporation
Characteristics subject to change without notice
7
Datasheet epc13x digital - V2.1
www.espros.ch
EPC [ ESPROS PHOTONICS CORP ]
