Page 1 of 9 123456789 LastLast
Results 1 to 10 of 85

Thread: Can anyone design me a lilliput regullator?

  1. #1
    Newbie
    Join Date
    Dec 2003
    Posts
    5

    Can anyone design me a lilliput regullator?

    Hello.
    Can anyone design me a regullator for the lilliput lcd display?
    Thank you.

  2. #2
    Constant Bitrate
    Join Date
    Apr 2003
    Posts
    189
    I'm building one right now. I'm using a LM2577 switching regulator in boost mode to convert 8-14V to 16V, then regulating it down to 12.6V (adjustable) using a LM317T. The 12.6V is to allow for voltage drop in the cable to the Lilliput and for more brightness.

    The LM2577 circuit is the same one in the NS data sheets (using a 100 uH inductor) and the LM317T part is also another no brainer.

  3. #3
    Maximum Bitrate
    Join Date
    Jun 2002
    Location
    Malaysia
    Posts
    624
    That is a great idea shchua.. but what is NS?

    btw, why dont you guys just use the DC regulator supplied with the LCD?

  4. #4
    Constant Bitrate
    Join Date
    Apr 2003
    Posts
    189
    Quote Originally Posted by masch
    That is a great idea shchua.. but what is NS?

    btw, why dont you guys just use the DC regulator supplied with the LCD?
    The regulator (egg shaped thingy) that came with my Lilliput has a dropout voltage of about 1.7V. When the engine is running, this is not a problem since the battery voltage is about 13.8V so the regulator's output is a nice solid 12V. When I turn off the engine, the battery voltage drops to about 12.8V causing the regulator output to drop to 11.1V. On my Lilliput, the brightness drops significantly which I dislike. I switched to using the +12V output from my Opus 150 but the problem is that the actual voltage at the Opus is 11.86V (non-adjustable according to Kris) and that drops to about 11.5V by the time it reaches the Lilliput.

    I've been running the Lilliput at 12.6V using my new regulator and its fine so far. It appears that the Lilliput will work down to about 10.8V with significant reduction in brightness so I'm thinking of varying the supply voltage to reduce the brightness at night.

    I'll recycle the Lilliput regulator (change one resistor) to produce 5V output for my USB hub.

  5. #5
    Constant Bitrate slffl's Avatar
    Join Date
    Jan 2004
    Posts
    118
    So the Opus doesn't provide a solid 12v? Oh man, I just fried my egg regulator and was planning on powering my lilliput through the opus, but I don't want a dim screen.

    Are there any other alternatives? Are there 12v regulators available for purchase anywhere?

  6. #6
    Newbie pugstyle's Avatar
    Join Date
    Feb 2004
    Location
    Denmark
    Posts
    16
    Quote Originally Posted by shchua
    I'm building one right now. I'm using a LM2577 switching regulator in boost mode to convert 8-14V to 16V, then regulating it down to 12.6V (adjustable) using a LM317T. The 12.6V is to allow for voltage drop in the cable to the Lilliput and for more brightness.

    The LM2577 circuit is the same one in the NS data sheets (using a 100 uH inductor) and the LM317T part is also another no brainer.
    can you put at pic down or a pcb so we can se how you will conect it

  7. #7
    Variable Bitrate Pokey's Avatar
    Join Date
    Apr 2004
    Location
    Tampa, Florida
    Posts
    284
    quote "convert 8-14V to 16V, then regulating it down to 12.6V"

    Could i ask what you gain by doing this? Seems inefficient to me, I mean a LM2577 is a regulator isnt it?
    Dual Lilliput's 70NP/C/T
    Syntax SV266AD KT266A
    AMD Athlon XP 2000
    Viking 256MB DDR
    D-Link Wireless 802.11B
    Seagate 120GB
    OrbitMicro 250W DC/DC converter
    SII Wireless Audio Link
    Digimoto OBD-II
    Earthmate GPS
    BU-303 USB GPS
    D-Link Bluetooth

  8. #8
    Low Bitrate
    Join Date
    Aug 2003
    Posts
    71
    Most converters including the LM2577 can only convert up or down, not both. When your desired output is 12V and the input can be either above or below you have two options:
    - Do it in two steps like shchua does
    - Build something which involves flyback transformers, which are usually expensive and hard to get if you don't want to order 1000+ of them.

    Using two steps can be reasonably efficient and still cheap.

  9. #9
    Constant Bitrate
    Join Date
    Apr 2003
    Posts
    189
    Quote Originally Posted by Pokey
    quote "convert 8-14V to 16V, then regulating it down to 12.6V"

    Could i ask what you gain by doing this? Seems inefficient to me, I mean a LM2577 is a regulator isnt it?
    Yes, but a LM2577 has a dropout voltage of about 1.5V. The battery voltage drops to about 12.6V when the engine is off, so the output voltage will drop to (12.6 - 1.5) or 11.1V. This causes the brightness of the Lilliput to dim noticeably.

    By boosting to 16V, then regulating down to 12.6V, I get a nice bright display whether the engine is on or off. As for the circuit diagram, I used the one straight from the National Semiconductor data sheets for the LM2577 - the inductor value used is 68 uH. This is followed by a LM317T linear regulator with R2/R1 ratio set for 12.6V output.

    If you don't mind having a dimmer display when the engine is off, you can omit the LM317T and configure the LM2577 for 12.6V output.

  10. #10
    MySQL Error Scouse Monkey's Avatar
    Join Date
    Mar 2004
    Location
    Bristol
    Posts
    9,727
    Hi, could you post links to or info where you get the data sheets you are using to build this.

    Cheers

Page 1 of 9 123456789 LastLast

Similar Threads

  1. Writeup Lilliput installation in TM-701L housing
    By spyhunter in forum LCD/Display
    Replies: 65
    Last Post: 05-17-2004, 06:58 PM
  2. Lilliput install in and Impreza, Lilliput issues
    By SubPuter in forum LCD/Display
    Replies: 76
    Last Post: 04-19-2004, 08:56 PM
  3. Replies: 2
    Last Post: 12-11-2003, 10:36 PM
  4. Nav system design review
    By zoom.zoom.zoom in forum GPS
    Replies: 5
    Last Post: 06-17-2003, 10:37 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •