Is there an IR receiver with external IR diode?

Question

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.

Answer 1

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.

Answer 2

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.

   

   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.

   

   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.