Seiko Instruments Introduces New Temperature Sensor IC Optimized for LED Lighting

By Seiko Instruments Inc., PRNE
Sunday, January 16, 2011

S-5855A Series temperature sensor IC enables safer, more efficient LED lighting designs -

TOKYO, January 17, 2011 - Seiko Instruments Inc. (SII) on Jan. 17 announced the S-5855A Series, a
PWM (pulse width modulation) output temperature sensor IC for LED lightning
designs. SII's S-5855A begins to decrease the duty ratio of PWM signal output
when the temperature exceeds the specified value. This change in the duty
ratio enables LED lighting circuits to avoid temperatures increasing above
design limits, improving safety and efficiency while reducing total design

Recently the market for LED lighting and display backlights has
experienced rapid growth. Although LED lighting has strong efficiency
advantages compared to incandescence, design consideration needs to be paid
to LED heat management to avoid shortening lifetimes. Generally this is
implemented by (1) performing thermal design to improve case heat
dissipation, (2) decreasing light intensity at high temperatures and (3)
stopping operation when the temperature rise exceeds the thermal design value
(putting out the lights).

SII's S-5855A is optimized for use in LED lighting systems for PC
laptops, tablets and other devices. It can also be used with any system
requiring temperature control. The S-5855A is connected to the DIM pin of an
LED driver IC to control the LED luminance, enhancing safety protection and
boosting efficiency.

The S-5855A maintains 100% luminescence up to the specified temperature.
Once the specified temperature is exceeded, the S-5855A decreases the PWM
output duty ratio gradually along with an increasing temperature. This
enables the LED luminance to diminish gradually. Also, since the S-5855A can
be connected to the DIM pin of the LED driver IC directly, it simplifies and
improves design safety as well as efficiency.

The S-5855A utilizes a super-small SNT-4A package, (1.2 x 1.6 x 0.5 mm)
enabling high density mounting. The standard SOT-23-5 package (2.9 x 2.8 x
1.3 mm) is also available. The S-5855A features low-voltage operation of
1.65V to 5.5V and is suitable for battery-operated portable equipment.

    Detailed information:

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    About Seiko Instruments Inc.
    Please visit

    Tomohiro Io
    Corporate Communications Dept.
    Seiko Instruments Inc.
    Tel: +81-43-211-1111
    Online Inquiry:

Tomohiro Io, Corporate Communications Dept., Seiko Instruments Inc., +81-43-211-1111, pr at,

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