23 Mar
2007
23 Mar
'07
5:13 p.m.
Fixing FE1250 Nec (actually two!), 22" monitor monsters.
Have the bulletin on fix these problems and problem is that I cannot
get this part easily here. Switchable off and on adjustable
regulator set for 3.3V in 5 pin SMD flat pack with heatsink tab.
The part number PQ20WZ51, marker: Sharp.
I can make a 3.3V regulator but best way to switch it off or on (fet
or transistor with low gate/base current? Data sheet for this
regulator is available had to dig inside sharp semiconductor area
even with google didn't find to find out what I need to rig the power
control side.
Cheers, Wizard
24 Mar
24 Mar
9:56 a.m.
How much current do you need? The LT3503 buck converter will do 1A and has
a shutdown pin. There are Maxim parts that use external FETs and also have
a shutdown pin.
If you have your heart set on a linear regulator, you might be able to use
an adjustable one and drive the ADJ pin to 5V to shut it off.
Clint
On Fri, 23 Mar 2007, jpero at sympatico.ca wrote:
Fixing FE1250 Nec (actually two!), 22" monitor
monsters.
Have the bulletin on fix these problems and problem is that I cannot
get this part easily here. Switchable off and on adjustable
regulator set for 3.3V in 5 pin SMD flat pack with heatsink tab.
The part number PQ20WZ51, marker: Sharp.
I can make a 3.3V regulator but best way to switch it off or on (fet
or transistor with low gate/base current? Data sheet for this
regulator is available had to dig inside sharp semiconductor area
even with google didn't find to find out what I need to rig the power
control side.
Cheers, Wizard
12:05 p.m.
On Mar 23, 2007, at 5:13 PM, jpero at sympatico.ca wrote:
Fixing FE1250 Nec (actually two!), 22" monitor
monsters.
Have the bulletin on fix these problems and problem is that I cannot
get this part easily here. Switchable off and on adjustable
regulator set for 3.3V in 5 pin SMD flat pack with heatsink tab.
The part number PQ20WZ51, marker: Sharp.
I can make a 3.3V regulator but best way to switch it off or on (fet
or transistor with low gate/base current? Data sheet for this
regulator is available had to dig inside sharp semiconductor area
even with google didn't find to find out what I need to rig the power
control side.
You will need what is known as a "high-side switch", which is
basically a P-channel MOSFET with some gate driver circuitry.
Or you can get a 3.3V regulator with an enable input. Linear
Technology (http://www.linear.com/) and Micrel (http://
www.micrel.com/) both make these...they shouldn't be difficult to get
ahold of in small quantities.
One I've used personally is the Micrel MIC29151-3.3BT; it is a
1.5A 3.3V linear regulator in a five-pin TO-220 package with a logic-
level active-high "enable" input.
-Dave
--
Dave McGuire
Port Charlotte, FL
7:26 p.m.
Dave McGuire wrote:
..
One I've used personally is the Micrel
MIC29151-3.3BT; it is a
1.5A 3.3V linear regulator in a five-pin TO-220 package with a logic-
level active-high "enable" input.
those LDO's are really handy for making low current 3.3v for things
like MMC disks...
I used one (ZR78L033GTA) which put out about 200ma and only had 3 pins.
(but, oops, well, I guess the thread was about turning on/off)
-brad
6307
days inactive
6308
days old
3 comments
4 participants
participants (4)
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brad＠heeltoe.com -
cctech＠porky.vax-11.org -
jpero＠sympatico.ca -
mcguire＠neurotica.com