lm2733x is NOT suitable

The operation of transmitters designed to jam or block wireless communications is a violation of the Communications Act of 1934, as amended ("Act"). See 47 U.S.C. Sections 301, 302a, 333. The Act prohibits any person from willfully or maliciously interfering with the radio communications of any station licensed or authorized under the Act or operated by the U.S. government. 47 U.S.C. Section 333. The manufacture, importation, sale or offer for sale, including advertising, of devices designed to block or jam wireless transmissions is prohibited. 47 U.S.C. Section 302a(b). Parties in violation of these provisions may be subject to the penalties set out in 47 U.S.C. Sections 501-510. Fines for a first offense can range as high as $11,000 for each violation or imprisonment for up to one year, and the device used may also be seized and forfeited to the U.S. government.

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
inh
 
Posts: 102
Joined: Mon Aug 27, 2007 6:49 am

lm2733x is NOT suitable

Post by inh »

Hi Guys - this is an appropriate replacement for the lm2733x and it's power inductor. the lm2733x is NOT suitable for output voltages below 16v!!!

these 2 parts should drop in - but I haven't worked out resistor values yet - please check out the datasheets to confirm I've got this right - it is the LM3731-"Y" notX...

LM2731YMFCT-ND IC CONV BOOST 22V FET SW SOT23-5
308-1500-1-ND POWER INDUCTOR 7.3UH 2.10A SMD
Top
spaceball_3000
 
Posts: 18
Joined: Fri Jul 20, 2007 9:40 pm

it will work ok, just done expect to draw too much ma.

Post by spaceball_3000 »

lm2733x does seem to work, with the correct resistor vaules you can adjust right to 5v, but I think at such a low voltagr value that this IC will not handle as much current at all.
Top
inh
 
Posts: 102
Joined: Mon Aug 27, 2007 6:49 am

replacements for 2733x and power inductor

Post by inh »

Hi there - yes I agree, but the datasheet says 2733x is suitable for 16v and above though, which is why I'm replacing it with 2731y, and a lower inductor - should be drop in replacement for both parts, and the datasheet even gives a 5v example...
Top
spaceball_3000
 
Posts: 18
Joined: Fri Jul 20, 2007 9:40 pm

Post by spaceball_3000 »

Agreed, seems to output max 600ma at 3.3v in, looks like I'll be giving this a try.

Thanks for the find!
Top
spaceball_3000
 
Posts: 18
Joined: Fri Jul 20, 2007 9:40 pm

Post by spaceball_3000 »

I'm going to test out the new 2731y when it get it.
Bbut I'm first going to try leaving the existing one in, and just swap in a 6uh inductor and see how that works.
Top
inh
 
Posts: 102
Joined: Mon Aug 27, 2007 6:49 am

early results

Post by inh »

Hi there - using a new inductor - 7.3uH and the 2731y, I'm getting 5.25v with the same resistors (12k and 39k) as with the 2733x. ie the new inductor and 2731y really are drop in - datasheet says you can get 3.5watts power out...
Top
spaceball_3000
 
Posts: 18
Joined: Fri Jul 20, 2007 9:40 pm

Post by spaceball_3000 »

Very good to hear about not having to change the resistors.
Well I'll be pushing the new power supply to it limits, I'll let you know of my results.
Top
WBVenom
 
Posts: 17
Joined: Fri Apr 11, 2008 3:33 am

Post by WBVenom »

Which L# on the schematic/board is the inductor you're speaking of?

EDIT: The L# is L1. (Found on bushing's wavebubble errata page).
Top
Locked
Please be positive and constructive with your questions and comments.

Return to “Wave Bubble”