From the 1580 data sheet.
"To achieve this dropout, a second low current input voltage 1V greater
than the output voltage, is required."
Like I said, ship it with a battery. ;-)
Then the "normal" part can have a dropout of 1.4V. You can't fight the
physics of the topology. For a NPN pass devi
The Linear Technology LT3070 (150mV @ 5A) , LT3071, LT1580 , and
LT1581 (700 mV @ 10A) are examples:
http://www.linear.com/product/LT1580
For comparison:
http://www.linear.com/product/LT1584
The LT1580 (0.8V @ 7A) has the same topology as the LT1584 (1.5V @ 7A)
except everything but the pass NP
I hate to be argumentative, but you can't be low drop out and use an
emitter follower. Draw the circuit and convince yourself. You would need
a high side driver scheme to drive the base/gate, and that require some
sort of boost converter. It can be done on switchmode chips, but not in
a linear
On Tue, 28 Feb 2012 00:13:18 -0500, "Charles P. Steinmetz"
wrote:
>Ed wrote:
>
>>So, for best HF noise performance where the input noise may be
>>large, it's best to use a follower or shunt regulator topology,
>>despite the lower efficiency - unless efficiency is more important.
>
>To put it mo
Well this is the granddaddy with 3V of dropout. Not much rejection at
high frequency, but the design is old. Modern LDOs are better,
especially with P-fet pass device.
http://www.ti.com/lit/ds/symlink/lm317-n.pdf
On 2/27/2012 9:13 PM, Charles P. Steinmetz wrote:
Ed wrote:
So, for best HF
Ed wrote:
So, for best HF noise performance where the input noise may be
large, it's best to use a follower or shunt regulator topology,
despite the lower efficiency - unless efficiency is more important.
To put it more bluntly, the last time I looked (it has been a while,
so there may be so
The PNP bipolar and P-channel MOSFET architectures do provide the
best low-dropout performance, but as I understand, do not provide the
best HF line rejection. Looking at the overall circuit - a high gain,
band-limited amplifier driving a "P" pass device puts it in a
common-base (or -gate) mode
-nuts-boun...@febo.com] On
Behalf Of Attila Kinali
Sent: Monday, February 27, 2012 12:48 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Power Supply Noise Affects Thunderbolt 1 PPS
On Sat, 18 Feb 2012 18:59:21 -0800
"Eric Lemmon" wrote:
> I hooked up
of precise time and frequency measurement
Subject: Re: [time-nuts] Power Supply Noise Affects Thunderbolt 1 PPS
Having designed LDO chips, people expect them to perform miracles
well beyond reality. If you have a PNP pass and you are sitting near
dropout, you get control loops that are an
-boun...@febo.com
Date: Mon, 27 Feb 2012 11:23:22
To: Discussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Power Supply Noise Affects Thunderbolt 1 PPS
On Mon, 27 Feb 2012 01:29:11 -0800
gary wrote:
>
e and frequency measurement
Subject: Re: [time-nuts] Power Supply Noise Affects Thunderbolt 1 PPS
>
> Having designed LDO chips, people expect them to perform miracles
> well beyond reality. If you have a PNP pass and you are sitting near
> dropout, you get control loops that are an
On Mon, 27 Feb 2012 01:29:11 -0800
gary wrote:
> On 2/27/2012 12:48 AM, Attila Kinali wrote:
> >
> > If you are really time-nutty, you can let the DC/DC converters produce
> > a voltage about 1V above what you need and use low noise LDOs (ie not
> > the 78xx or LM317& Co) to produce the voltages
>
> Having designed LDO chips, people expect them to perform miracles
> well beyond reality. If you have a PNP pass and you are sitting near
> dropout, you get control loops that are an ugly combination of a path
> to keep the PNP from getting saturated plus one to control the
> voltage.
>
> I n
>
> Having designed LDO chips, people expect them to perform miracles
> well beyond reality. If you have a PNP pass and you are sitting near
> dropout, you get control loops that are an ugly combination of a path
> to keep the PNP from getting saturated plus one to control the
> voltage.
>
> I n
On 2/27/2012 12:48 AM, Attila Kinali wrote:
If you are really time-nutty, you can let the DC/DC converters produce
a voltage about 1V above what you need and use low noise LDOs (ie not
the 78xx or LM317& Co) to produce the voltages for the thunderbolt.
This should give you a 60-80dB damping o
On Sat, 18 Feb 2012 18:59:21 -0800
"Eric Lemmon" wrote:
> I hooked up a linear triple-output bench supply to run the Thunderbolt, and
> now the 8040C locked up perfectly on the 1 PPS signal. Since I don't want
> to tie up one of my bench power supplies to run the Thunderbolt, I plan to
> try add
I recently acquired a Symmetricom 8040C Rubidium Standard, hoping to use one
of my Thunderbolt GPSDOs to further refine its 10 MHz output. To my
surprise, connecting the 1 PPS output to the 8040C did nothing- the "1 PPS
SYNC" indicator stayed dark. I hooked up my other Thunderbolt and got the
sa
il 29, 2011 10:35 PM
Subject: Re: [time-nuts] Power supply noise
...and I used to think batteries were a good/clean source of power. They
are better than a linear power supply... yet they make very good
temperature sensors too!
What is the perfect source of power? Clean, no ripple, no variation b
-
From: "Attila Kinali"
To: "Discussion of precise time and frequency measurement"
Sent: Friday, April 29, 2011 11:11 AM
Subject: Re: [time-nuts] Power supply noise
On Thu, 28 Apr 2011 17:04:25 -0600
Joseph Gray wrote:
Power supply noise and ripple has been mentioned be
On Thu, 28 Apr 2011 17:04:25 -0600
Joseph Gray wrote:
> Power supply noise and ripple has been mentioned before, in relation
> to OCXO's and rubidiums. So, what is considered acceptable in these
> applications?
This highly depends on your system and what you want to achieve.
Just like anything e
Power supply noise and ripple has been mentioned before, in relation
to OCXO's and rubidiums. So, what is considered acceptable in these
applications?
Joe Gray
W5JG
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