Comment 1 by Joerg Reisenweber, Nov 20, 2013

http://www.digikey.es/product-search/en?FV=fff4001e%2Cfff801dd%2Cfffc
01db&mnonly=0&newproducts=0&ColumnSort=0&page=1&s
tock=1&quantity=0&ptm=0&fid=0&pageSize=25

Comment 2 by Joerg Reisenweber, Nov 20, 2013

http://www.digikey.com/product-detail/en/SFH 
7741-Z/475-2663-1-ND/1893865?cur=USD
seems right component. Seems also available, despite OSRAM says 
"obsolete"

Comment 3 by Joerg Reisenweber, Nov 20, 2013

According to
http://photonics.com/Article.aspx?AID=33439
I suspect we have 7740 for camdoor slider. This seems not in line 
with the datashhets and Rprog in N900 schematics.

Comment 4 by Nikolaus Schaller, Nov 25, 2013

Yes, the 7740 looks quite like the one used. But what I wonder is 
why there is a proximity sensor at all. The main purpose should be 
to detect if the handset is hold to an ear and turn off speakers and 
display/keypad backlight. This means a sensor mounted in the display 
assembly. And not one near the camera?
Or did they simply use two of them in lack of some simpler sensor.

Comment 5 by Joerg Reisenweber, Nov 25, 2013

There are 2 similar proximity sensors, one in display half next to 
front camera [reflective optical switch N1540] with 
"incorrect" Rprog [R1541 150R], to detect when you hold 
phone to ear, to lock touchscreen and thus avoid false keypresses 
and to dim backlight. 
And a similar one [N5820 Main Camera Cover Switch] (though with a 
different "correct" Rprog [R5820 470R]) for sensing the 
black/white stripe on cam-door

Comment 6 by Joerg Reisenweber, Nov 25, 2013

operating range of the front proxi is ~30mm so it kicks in before 
you touch the screen with your ear.
The operating distance of main cam cover(door) switch is in the 
range of 1..2mm from sensor to black/white stripe on cam door inner 
side. AIUI the difference between 7741 and 7740 is for the distance 
they are designed for, according to 
http://photonics.com/Article.aspx?AID=33439. Rprog is another means 
to determine operation distance, however 150R is not mentioned as 
valid vakue in the datasheet I have.

Comment 7 by Joerg Reisenweber, Nov 25, 2013

My suspicion is that they obsoleted the 7740 since the 7741 is doing 
the job just good enough to replace 7740