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I need an IR receiver that can directly be used with a microprocessor - the TSOP series from Vishay seems to fit well and there are enough tutorials and software libraries to make use of it. Unfortunately in my design I only have space for a normal 3mm (preferably) or 5mm LED receiver diode. Is there a simple IR driver chip that works like the TSOP receivers but with an external IR diode? So it should have 4 pins (Vs, OUT, GND, LED-INPUT) instead of 3 pins, three of them (Vs, OUT, GND) to be used as IR receivers with build-in IR diode and the fourth to connect the diode to (and to GND, of course).

P.S: Maybe a bit more background about my actual project: I want to put an IR receivers into a LEGO® and/or DUPLO® bricks, such as shown in this project. The bricks shall receive signals such as "brick number 12, switch on", "brick number 7, send temperature" etc. from a TV remote control, from an IR keyboard and/or from a custom IR sender at the ceiling. There is enough space at least in a DUPLO brick for one or two additional microprocessors (e.g. ATtiny 13/45/85) and a few wires and resistors. The only possible solution I found so far is using transparent bricks.

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I'd suggest including more information about what exactly you're trying to achieve / sense / detect. The TSOP is designed to be used as a receiver which can receive a few bits of information. Is that what you want? Or do you just want to be able to detect whether there is IR shining onto it or not? Do you have room for more circuitry away from where your diode is? If so, how much? –  Chintalagiri Shashank Feb 20 '13 at 10:22
    
Avago's APDS-9700 and APDS-9702 might do what you want, but they are meant for proximity sensors rather than data links, so the data rate you can receive through them may not be as high as you want. Also they include LED driver circuits you don't need, but can probably safely ignore. –  The Photon Feb 20 '13 at 17:12

2 Answers 2

Most IR Receivers have circuitry inside to strip the (typically) 38khz carrier wave used in IR remote applications. The Diode is closely matched to this, and is often encased in a shield to protect against noise. You would be hard pressed to find a different form factor.

What you can do, if the Lego brick only allows a typical 3 or 5mm led to be inserted, is use a piece of 3 or 5mm clear acrylic rod, cut to a short length and flame polished, inserted into the brick, with the IR receiver inside facing the rod. A cheap light pipe.

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If Vishay IR receivers such as TSOP1738 meet the purpose, and the sole constraint is size, there are two types of devices within the Vishay IR receiver family to consider:

  1. Surface mount equivalents with integrated photodiode, preamplifier, AGC and daylight filter, e.g. Vishay TSOP37438.

    TSOP37438

    0.8 x 3.95 x 3.95 mm package, midway between the area dimensions of 3 mm and 5 mm photodiodes. Vs, Gnd and Vout are every other contact along one edge, with a 0.75 mm pin pitch, so can be hand soldered with a bit of skill. The rest of the contacts are all ground, and can be ignored.

    Same 3 connections as the through-hole IR receivers, identical active-low output. No change needed in schematic design or microcontroller code.

  2. Vishay IR preamplifier with AGC, designed for use with external photodiodes, such as VSOP58438

    0.76 x 2.0 x 2.0 package with pin-outs precisely as described in the question, i.e. one additional contact for photodiode. With a 0.5 mm pin pitch, not quite as easy to hand-solder as the above.

    Schematic

    Functionally similar to the TSOP through-hole IR receivers, just some additional work finding a matching photodiode.

    The challenges will be noise picked up between the photodiode and this preamp, and the ambient light causing interference if the photodiode is not tightly daylight-filtered.

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protected by W5VO Feb 19 '13 at 21:53

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