Phototransistors Offer High Contrast Ratio

The OP750 and OP755 silicon, NPN phototransistors with integrated base-emitter resistors have enhanced low current roll-off characteristics that improve contrast ratio and immunity to background lighting. The integral base-emitter resistor causes the phototransistor to ignore small changes in ambient light while providing sharp turn on characteristics in low contrast applications. For example, the presence of a transparent material or varying shades of gray cause only slight variations in a standard phototransistor's current, while the base-emitter phototransistor's output is a sharply different, easily detectable current difference. Both devices are offered in side looking, lateral leaded packages. The OP750 has an external lens, and the OP755 has a counter-sunk lens.