Date: 24/07/2012

Light detect IC for dark sensing consumes only nano Amps of current

Seiko Instruments Inc. has announced the new "S-5470" series photo detect ICs³ that enable design of light/dark detection switch circuits by only consuming nano amperes of current (an near zero-power consumption) when combined with a photo diode, LED, or other photovoltaic devices.

Seiko explains: Due to the photo voltaic effect, photodiodes and LEDs generate tiny electrical current when exposed to light. Conventional ICs require amplifiers to sense the minute current, and consume significant power to operate. In contrast, SII's new "S-5470" series ICs detect the same minute current without the need for amplifiers using SII's unique low power CMOS technology. This approach has achieved zero-power consumption (nW class) circuit designs. It also enables the design of shading detection switches based on illumination differences between two photo voltaic devices.

Typical applications include auto power-off functionality detecting light/dark conditions, automatic lighting during darkness, and non-contact switching when the device is covered by a hand. Some examples would be a wireless mouse that turns itself on when the user grasps it for use; smartphones that activate when their covers are opened; clocks that inactivate chimes during periods of darkness; equipment that operates when its box is opened, and the like.

The "S-5470" series ICs feature super-low power consumption: 0.1 nA (typ.) at a 5.5V supply voltage; can be used with a number of different photovoltaic devices including photo diodes, LEDs, solar batteries, etc.; wide operating voltage range: 0.9V-5.5V; and small SOT-23-5 package (2.9x2.8x1.3 mm).

Detailed information at:
http://datasheet.sii-ic.com/en/photo_ic/S5470_E.pdf