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Photomicro Sensor: Notation and Terminology for Phototransistor Output

FAQ No. FAQ01138

Primary Contents

Question

What is the notation and terminology for a Phototransistor output?

Answer

The following table provides a description of notation and terminology used in catalogs for Photomicrosensors built into equipment with a phototransistor output.

Phototransistor Output

NotationItemDescription
IFPPulse forward currentThe maximum pulse current that is allowed to flow continuously from the
anode to cathode of an LED under a specified temperature, a repetition
period, and a pulse width condition.
IcCollector currentThe current that flows to the collector junction of a phototransistor.
PcCollector dissipationThe maximum power that is consumed by the collector junction of a
phototransistor.
IDDark currentThe current leakage of the phototransistor when a specified bias voltage is
imposed on the phototransistor so that the polarity of the collector is positive
and that of the emitter is negative on condition that the illumination of the
Photomicrosensor is 0 lx.
ILLight currentThe collector current of a phototransistor under a specified input current
condition and at a specified bias voltage.
VCE(sat)Collector-emitter
saturated voltage
The ON-state voltage between the collector and emitter of a phototransistor
under a specified bias current condition.
ILEAKLeakage currentThe collector current of a phototransistor under a specified input current
condition and at a specified bias voltage when the phototransistor is not
exposed to light.
trRising timeThe time required for the leading edge of an output waveform of a
phototransistor to rise from 10% to 90% of its final value when a specified
input current and bias condition is given to the phototransistor.
tfFalling timeThe time required for the trailing edge of an output waveform of a
phototransistor to decrease from 90% to 10% of its final value when a
specified input current and bias condition is given to the phototransistor.
VCEOCollector-emitter voltageThe maximum positive voltage that can be applied to the collector of a
phototransistor with the emitter at reference potential.
VECOEmitter-collector voltageThe maximum positive voltage that can be applied to the emitter of a
phototransistor with the collector at reference potential.