LM1117 with ceramic cap load

[John Larkin]

I did this with the LM317, so thought I'd verify it with the 1117.

https://www.dropbox.com/s/cboxe03ef0dhy22/LM1117_Cload.JPG?raw=1

https://www.dropbox.com/s/yt4ehon0pzi8ni5/LM1117_Comp.JPG?raw=1

Adding that 47n cap makes it low-esr capacitor load stable. I have no
clue why.

I really like the LM1117. It's cheap, tough, and has lower dropout
than the 317. We've used 56,000 so far.






--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[bitrex]

On 6/17/19 7:44 PM, John Larkin wrote:

I did this with the LM317, so thought I'd verify it with the 1117.

https://www.dropbox.com/s/cboxe03ef0dhy22/LM1117_Cload.JPG?raw=1

https://www.dropbox.com/s/yt4ehon0pzi8ni5/LM1117_Comp.JPG?raw=1

Adding that 47n cap makes it low-esr capacitor load stable. I have no
clue why.

I really like the LM1117. It's cheap, tough, and has lower dropout
than the 317. We've used 56,000 so far.

<https://en.wikipedia.org/wiki/Pole_splitting>

the LM1117 doesn't have any internal frequency compensation, it's just a
Brokaw band-gap reference that's also kinda its own error amp connected
to a PNP-styled sziklai pair output stage.

With a high ESR cap the internal capacitance of the Sziklai + error amp
output impedance, output resistance of the PNP, cap C and ESR, and load
R make a system with two poles and one zero that have break frequencies
below the amps unity gain rolloff - stable.

With a low ESR cap the ESR zero shifts up and out beyond the unity gain
frequency leaving two poles below the UGF - bad phase margin.

With the extra cap the two poles that remain are split with one moving
lower and the other moving up and out - stable again, but slower.

 

[George Herold]

On Monday, June 17, 2019 at 7:46:48 PM UTC-4, John Larkin wrote:

I did this with the LM317, so thought I'd verify it with the 1117.

https://www.dropbox.com/s/cboxe03ef0dhy22/LM1117_Cload.JPG?raw=1

https://www.dropbox.com/s/yt4ehon0pzi8ni5/LM1117_Comp.JPG?raw=1

Adding that 47n cap makes it low-esr capacitor load stable. I have no
clue why.

I really like the LM1117. It's cheap, tough, and has lower dropout
than the 317. We've used 56,000 so far.



huh, I don't know the LM1117, Thx.

Probably unrelated, but using an lm317 as opamp -> power transistor
(Emitter follower)
Here is output vs different load resistors,
1k ohm
https://www.dropbox.com/s/gpl34en11atr0tq/1k_load.bmp?dl=0

100 ohms
https://www.dropbox.com/s/3zzkrc9swdbsyk3/100_load.bmp?dl=0

and 10 ohms
https://www.dropbox.com/s/0otm0cy6tx92ktc/10Ohm.bmp?dl=0

(This data was taken a week or two ago.. but I forgot to post it.)
GH

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Tue, 18 Jun 2019 10:19:46 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

On Monday, June 17, 2019 at 7:46:48 PM UTC-4, John Larkin wrote:
I did this with the LM317, so thought I'd verify it with the 1117.

https://www.dropbox.com/s/cboxe03ef0dhy22/LM1117_Cload.JPG?raw=1

https://www.dropbox.com/s/yt4ehon0pzi8ni5/LM1117_Comp.JPG?raw=1

Adding that 47n cap makes it low-esr capacitor load stable. I have no
clue why.

I really like the LM1117. It's cheap, tough, and has lower dropout
than the 317. We've used 56,000 so far.



huh, I don't know the LM1117, Thx.

I call it an "mdo", about half the dropout of a 317. It can regulate
+5 to +3.3 reliably.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Tom Del Rosso]

John Larkin wrote:

On Tue, 18 Jun 2019 10:19:46 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Monday, June 17, 2019 at 7:46:48 PM UTC-4, John Larkin wrote:
I did this with the LM317, so thought I'd verify it with the 1117.

https://www.dropbox.com/s/cboxe03ef0dhy22/LM1117_Cload.JPG?raw=1

https://www.dropbox.com/s/yt4ehon0pzi8ni5/LM1117_Comp.JPG?raw=1

Adding that 47n cap makes it low-esr capacitor load stable. I have
no clue why.

I really like the LM1117. It's cheap, tough, and has lower dropout
than the 317. We've used 56,000 so far.



huh, I don't know the LM1117, Thx.

I call it an "mdo", about half the dropout of a 317. It can regulate
+5 to +3.3 reliably.

Is 11xx a series like 1xx, 2xx and 3xx used to be? The old series were
different in temperature range, so I know it's not quite the same thing.

I mean, did they carry over other 3xx parts to 11xx?

 

[whit3rd]

On Friday, June 21, 2019 at 1:02:27 AM UTC-7, Tom Del Rosso wrote:
> John Larkin wrote:

[about the LM1117]

I call it an "mdo", about half the dropout of a 317. It can regulate
+5 to +3.3 reliably.

Is 11xx a series like 1xx, 2xx and 3xx used to be? The old series were
different in temperature range, so I know it's not quite the same thing.

I mean, did they carry over other 3xx parts to 11xx?

The old NatSemi numbers were LM1xx for mil spec temperature range, LM2xx for
'industrial', LM3xx for 'commercial', but the LT1117 is an LT (now Analog Devices) part (often copied)
that uses a part number with a letter suffix for the 'grade' instead of changing
the digit.

 

[John Larkin]

On Fri, 21 Jun 2019 04:02:20 -0400, "Tom Del Rosso"
<fizzbintuesday@that-google-mail-domain.com> wrote:

John Larkin wrote:
On Tue, 18 Jun 2019 10:19:46 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Monday, June 17, 2019 at 7:46:48 PM UTC-4, John Larkin wrote:
I did this with the LM317, so thought I'd verify it with the 1117.

https://www.dropbox.com/s/cboxe03ef0dhy22/LM1117_Cload.JPG?raw=1

https://www.dropbox.com/s/yt4ehon0pzi8ni5/LM1117_Comp.JPG?raw=1

Adding that 47n cap makes it low-esr capacitor load stable. I have
no clue why.

I really like the LM1117. It's cheap, tough, and has lower dropout
than the 317. We've used 56,000 so far.



huh, I don't know the LM1117, Thx.

I call it an "mdo", about half the dropout of a 317. It can regulate
+5 to +3.3 reliably.

Is 11xx a series like 1xx, 2xx and 3xx used to be? The old series were
different in temperature range, so I know it's not quite the same thing.

I mean, did they carry over other 3xx parts to 11xx?

The 1117 is available in four fixed voltages and the ADJ version.

http://www.ti.com/lit/gpn/LM1117

If you happen to need 1.25 volts (like for a CPU core) and 2.5 for
something else, you can ground one ADJ pin, and stack the other
regulator into that. No resistors needed.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[George Herold]

On Friday, June 21, 2019 at 10:24:40 PM UTC-4, John Larkin wrote:

On Fri, 21 Jun 2019 04:02:20 -0400, "Tom Del Rosso"
fizzbintuesday@that-google-mail-domain.com> wrote:

John Larkin wrote:
On Tue, 18 Jun 2019 10:19:46 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Monday, June 17, 2019 at 7:46:48 PM UTC-4, John Larkin wrote:
I did this with the LM317, so thought I'd verify it with the 1117.

https://www.dropbox.com/s/cboxe03ef0dhy22/LM1117_Cload.JPG?raw=1

https://www.dropbox.com/s/yt4ehon0pzi8ni5/LM1117_Comp.JPG?raw=1

Adding that 47n cap makes it low-esr capacitor load stable. I have
no clue why.

I really like the LM1117. It's cheap, tough, and has lower dropout
than the 317. We've used 56,000 so far.



huh, I don't know the LM1117, Thx.

I call it an "mdo", about half the dropout of a 317. It can regulate
+5 to +3.3 reliably.

Is 11xx a series like 1xx, 2xx and 3xx used to be? The old series were
different in temperature range, so I know it's not quite the same thing.

I mean, did they carry over other 3xx parts to 11xx?



The 1117 is available in four fixed voltages and the ADJ version.

http://www.ti.com/lit/gpn/LM1117

If you happen to need 1.25 volts (like for a CPU core) and 2.5 for
something else, you can ground one ADJ pin, and stack the other
regulator into that. No resistors needed.

And it comes in a to-220 pac. I've got a few heater circuits
using spendy lm395's and I should try them with '317's and '1117s..

George H.

--

John Larkin Highland Technology, Inc

lunatic fringe electronics