Depletion FET regulator...

[bitrex]

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

<https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94>

 

[Fred Bloggs]

On Thursday, July 13, 2023 at 2:04:20 PM UTC-4, bitrex wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

Vout= Vzener - VGS(Iout), where VGS(Iout) is the reverse VGS ( a negative voltage ) corresponding to Iout through the load with voltage Vout across it.
Vout may not be highly accurate, but dVout/dIout= - dVGS(Iout)/dIout is usable.

 

[piglet]

On 13/07/2023 7:04 pm, bitrex wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

Should be extremly clean, what were you fearing?

piglet

 

[John Larkin]

On Thu, 13 Jul 2023 14:04:09 -0400, bitrex <user@example.net> wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

Startup, the fet acts lilke a resistor until it regulates and flattens
out. Regulation will be mediocre.

Shutdown, as the input drops it may discharge the load through the fet
substrate diode.

May as well buy an LM78xx or something.

Depletion fets are great in places, but that\'s not one. It might be OK
for a high voltage reg where ICs aren\'t available.

It might fry if the load shorts.

I don\'t understand Fig 12. Why two resistors?

 

[Fred Bloggs]

On Thursday, July 13, 2023 at 2:28:12 PM UTC-4, John Larkin wrote:

On Thu, 13 Jul 2023 14:04:09 -0400, bitrex <us...@example.net> wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94
Startup, the fet acts lilke a resistor until it regulates and flattens
out. Regulation will be mediocre.

Shutdown, as the input drops it may discharge the load through the fet
substrate diode.

May as well buy an LM78xx or something.

Depletion fets are great in places, but that\'s not one. It might be OK
for a high voltage reg where ICs aren\'t available.

It might fry if the load shorts.

I don\'t understand Fig 12. Why two resistors?

It probably gets hung somewhere on the combined I-V of the series LEDs. They have it drawn funnily, but the FET CCS configuration is in parallel with a resistor from the input voltage source to the LEDS. That probably gets them in some kind of ballpark, and CCS sort of keeps things constant from there. The note is not their best work.

 

[John Larkin]

On Thu, 13 Jul 2023 11:42:26 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:28:12?PM UTC-4, John Larkin wrote:
On Thu, 13 Jul 2023 14:04:09 -0400, bitrex <us...@example.net> wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94
Startup, the fet acts lilke a resistor until it regulates and flattens
out. Regulation will be mediocre.

Shutdown, as the input drops it may discharge the load through the fet
substrate diode.

May as well buy an LM78xx or something.

Depletion fets are great in places, but that\'s not one. It might be OK
for a high voltage reg where ICs aren\'t available.

It might fry if the load shorts.

I don\'t understand Fig 12. Why two resistors?

It probably gets hung somewhere on the combined I-V of the series LEDs. They have it drawn funnily, but the FET CCS configuration is in parallel with a resistor from the input voltage source to the LEDS. That probably gets them in some kind of ballpark, and CCS sort of keeps things constant from there. The note is not their best work.

It\'s a solution looking for a problem.

I like the SOT23 Supertex part and an LED as a power supply cap
discharger and warning. Nice linear discharge.

 

[Fred Bloggs]

On Thursday, July 13, 2023 at 2:04:20 PM UTC-4, bitrex wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not sensational.

 

[Fred Bloggs]

On Thursday, July 13, 2023 at 2:48:37 PM UTC-4, John Larkin wrote:

On Thu, 13 Jul 2023 11:42:26 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Thursday, July 13, 2023 at 2:28:12?PM UTC-4, John Larkin wrote:
On Thu, 13 Jul 2023 14:04:09 -0400, bitrex <us...@example.net> wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94
Startup, the fet acts lilke a resistor until it regulates and flattens
out. Regulation will be mediocre.

Shutdown, as the input drops it may discharge the load through the fet
substrate diode.

May as well buy an LM78xx or something.

Depletion fets are great in places, but that\'s not one. It might be OK
for a high voltage reg where ICs aren\'t available.

It might fry if the load shorts.

I don\'t understand Fig 12. Why two resistors?

It probably gets hung somewhere on the combined I-V of the series LEDs. They have it drawn funnily, but the FET CCS configuration is in parallel with a resistor from the input voltage source to the LEDS. That probably gets them in some kind of ballpark, and CCS sort of keeps things constant from there. The note is not their best work.
It\'s a solution looking for a problem.

I like the SOT23 Supertex part and an LED as a power supply cap
discharger and warning. Nice linear discharge.

Right, SuperTex has some really super application circuits for the depletion modes. The off line regulators are particularly original and valuable. This old app note looks like it borrowed a bunch of pat regulator configurations from the linear handbooks and stuck a depletion in them.

 

[Dimiter_Popoff]

On 7/13/2023 21:27, John Larkin wrote:

On Thu, 13 Jul 2023 14:04:09 -0400, bitrex <user@example.net> wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

Startup, the fet acts lilke a resistor until it regulates and flattens
out. Regulation will be mediocre.

Shutdown, as the input drops it may discharge the load through the fet
substrate diode.

May as well buy an LM78xx or something.

I had similar thoughts - only I thought jfet, 4391 or so.
Until I saw the 600V D-S voltage.

 

[John Larkin]

On Thu, 13 Jul 2023 22:17:09 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:

On 7/13/2023 21:27, John Larkin wrote:
On Thu, 13 Jul 2023 14:04:09 -0400, bitrex <user@example.net> wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

Startup, the fet acts lilke a resistor until it regulates and flattens
out. Regulation will be mediocre.

Shutdown, as the input drops it may discharge the load through the fet
substrate diode.

May as well buy an LM78xx or something.

I had similar thoughts - only I thought jfet, 4391 or so.
Until I saw the 600V D-S voltage.

The LND150 (or 250, looks the same) is rated 500 volts. Unlike jfets,
Idss is very consistent between parts, about 1.6 mA for these.

Supertex has a bigger part, DN2530, in SOT-89. Nice.

 

[John Larkin]

On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not sensational.

Real low voltage zeners are awful too.

Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.

 

[bitrex]

On 7/13/2023 3:46 PM, John Larkin wrote:

On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not sensational.

Real low voltage zeners are awful too.

Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.

I\'m designing a kind of evaluation board for a SPLC where it might be
nice to accommodate a wide range of input voltages, since the part is
mixed-signal and could be interfaced to higher voltage stuff, relays,
etc..I may put some kind of open-collector output drivers on the board
also so it might be nice if the whole thing could be powered by whatever
the driver\'s output is tolerant to, say 50 V.

The SPLC handily supplies some spare internal comparators with a
selectable Vref on their inverting \"pin\" so I was thinking just add a
depletion FET and the part could become its own wide input range linear
regulator.

But I have concerns about how a depletion FET would behave in that role,
particularly on start-up, with the chip trying to boostrap itself to be
part of its own regulator. Maybe that\'s too clever.

 

[bitrex]

On 7/13/2023 6:02 PM, bitrex wrote:

On 7/13/2023 3:46 PM, John Larkin wrote:
On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not sensational.

Real low voltage zeners are awful too.
Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.




I\'m designing a kind of evaluation board for a SPLC where it might be
nice to accommodate a wide range of input voltages, since the part is
mixed-signal and could be interfaced to higher voltage stuff, relays,
etc..I may put some kind of open-collector output drivers on the board
also so it might be nice if the whole thing could be powered by whatever
the driver\'s output is tolerant to, say 50 V.

The SPLC handily supplies some spare internal comparators with a
selectable Vref on their inverting \"pin\" so I was thinking just add a
depletion FET and the part could become its own wide input range linear
regulator.

Hmm, actually if the pass device is depletion N fet I guess the error
amp needs to be configured like a emitter/source follower, not a PNP ldo.

 

[piglet]

On 13/07/2023 23:02, bitrex wrote:

On 7/13/2023 3:46 PM, John Larkin wrote:
On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not sensational.

Real low voltage zeners are awful too.
Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.




I\'m designing a kind of evaluation board for a SPLC where it might be
nice to accommodate a wide range of input voltages, since the part is
mixed-signal and could be interfaced to higher voltage stuff, relays,
etc..I may put some kind of open-collector output drivers on the board
also so it might be nice if the whole thing could be powered by whatever
the driver\'s output is tolerant to, say 50 V.

The SPLC handily supplies some spare internal comparators with a
selectable Vref on their inverting \"pin\" so I was thinking just add a
depletion FET and the part could become its own wide input range linear
regulator.

But I have concerns about how a depletion FET would behave in that role,
particularly on start-up, with the chip trying to boostrap itself to be
part of its own regulator. Maybe that\'s too clever.

I don\'t know about SPLC and how cleanly its vref starts up but a plain
zener and depl fet would be clean. Imprecision of zener could be solved
by using TL431 instead.

piglet

 

[piglet]

On 13/07/2023 23:21, bitrex wrote:

On 7/13/2023 6:02 PM, bitrex wrote:
On 7/13/2023 3:46 PM, John Larkin wrote:
On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not
sensational.

Real low voltage zeners are awful too.
Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.




I\'m designing a kind of evaluation board for a SPLC where it might be
nice to accommodate a wide range of input voltages, since the part is
mixed-signal and could be interfaced to higher voltage stuff, relays,
etc..I may put some kind of open-collector output drivers on the board
also so it might be nice if the whole thing could be powered by
whatever the driver\'s output is tolerant to, say 50 V.

The SPLC handily supplies some spare internal comparators with a
selectable Vref on their inverting \"pin\" so I was thinking just add a
depletion FET and the part could become its own wide input range
linear regulator.

Hmm, actually if the pass device is depletion N fet I guess the error
amp needs to be configured like a emitter/source follower, not a PNP ldo.

That app note circuit is fine for a simple pre-regulator but not going
to be useful for getting a well defined output voltage because in
addition to the zener tolerance there is the poorly defined Vgs.

Much better use a TL431 or LM4040 with feedback from the output.

piglet

 

[John Larkin]

On Thu, 13 Jul 2023 18:02:45 -0400, bitrex <user@example.net> wrote:

On 7/13/2023 3:46 PM, John Larkin wrote:
On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not sensational.

Real low voltage zeners are awful too.

Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.




I\'m designing a kind of evaluation board for a SPLC where it might be
nice to accommodate a wide range of input voltages, since the part is
mixed-signal and could be interfaced to higher voltage stuff, relays,
etc..I may put some kind of open-collector output drivers on the board
also so it might be nice if the whole thing could be powered by whatever
the driver\'s output is tolerant to, say 50 V.

The SPLC handily supplies some spare internal comparators with a
selectable Vref on their inverting \"pin\" so I was thinking just add a
depletion FET and the part could become its own wide input range linear
regulator.

But I have concerns about how a depletion FET would behave in that role,
particularly on start-up, with the chip trying to boostrap itself to be
part of its own regulator. Maybe that\'s too clever.

SPLC?

 

[bitrex]

On 7/14/2023 11:30 AM, John Larkin wrote:

On Thu, 13 Jul 2023 18:02:45 -0400, bitrex <user@example.net> wrote:

On 7/13/2023 3:46 PM, John Larkin wrote:
On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not sensational.

Real low voltage zeners are awful too.

Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.




I\'m designing a kind of evaluation board for a SPLC where it might be
nice to accommodate a wide range of input voltages, since the part is
mixed-signal and could be interfaced to higher voltage stuff, relays,
etc..I may put some kind of open-collector output drivers on the board
also so it might be nice if the whole thing could be powered by whatever
the driver\'s output is tolerant to, say 50 V.

The SPLC handily supplies some spare internal comparators with a
selectable Vref on their inverting \"pin\" so I was thinking just add a
depletion FET and the part could become its own wide input range linear
regulator.

But I have concerns about how a depletion FET would behave in that role,
particularly on start-up, with the chip trying to boostrap itself to be
part of its own regulator. Maybe that\'s too clever.

SPLC?

Ope, SPLD, rather

 

[bitrex]

On 7/14/2023 12:19 PM, bitrex wrote:

On 7/14/2023 11:30 AM, John Larkin wrote:
On Thu, 13 Jul 2023 18:02:45 -0400, bitrex <user@example.net> wrote:

On 7/13/2023 3:46 PM, John Larkin wrote:
On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not
sensational.

Real low voltage zeners are awful too.
Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.




I\'m designing a kind of evaluation board for a SPLC where it might be
nice to accommodate a wide range of input voltages, since the part is
mixed-signal and could be interfaced to higher voltage stuff, relays,
etc..I may put some kind of open-collector output drivers on the board
also so it might be nice if the whole thing could be powered by whatever
the driver\'s output is tolerant to, say 50 V.

The SPLC handily supplies some spare internal comparators with a
selectable Vref on their inverting \"pin\" so I was thinking just add a
depletion FET and the part could become its own wide input range linear
regulator.

But I have concerns about how a depletion FET would behave in that role,
particularly on start-up, with the chip trying to boostrap itself to be
part of its own regulator. Maybe that\'s too clever.

SPLC?


Ope, SPLD, rather

Small Programmable Logic Controller
Simple Programmable Logic Device
Simple Programmable Logic Controller

Etc...is the term \"controller\" reserved for integrated modules but an
individual chip is a \"device\"?

 

[Fred Bloggs]

On Thursday, July 13, 2023 at 6:02:53 PM UTC-4, bitrex wrote:

On 7/13/2023 3:46 PM, John Larkin wrote:
On Thu, 13 Jul 2023 11:51:12 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Thursday, July 13, 2023 at 2:04:20?PM UTC-4, bitrex wrote:
What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

I\'m getting 45 mV/mA from their I-V curve of that part. Not sensational.

Real low voltage zeners are awful too.

Who wants a 5 volt regulator that might be 4, might be 6?

One could hang a depletion fet on top of a 3-terminal regulator to
extend its input voltage range. That might need zero additional parts,
ignoring the heat sink.


I\'m designing a kind of evaluation board for a SPLC where it might be
nice to accommodate a wide range of input voltages, since the part is
mixed-signal and could be interfaced to higher voltage stuff, relays,
etc..I may put some kind of open-collector output drivers on the board
also so it might be nice if the whole thing could be powered by whatever
the driver\'s output is tolerant to, say 50 V.

The SPLC handily supplies some spare internal comparators with a
selectable Vref on their inverting \"pin\" so I was thinking just add a
depletion FET and the part could become its own wide input range linear
regulator.

But I have concerns about how a depletion FET would behave in that role,
particularly on start-up, with the chip trying to boostrap itself to be
part of its own regulator. Maybe that\'s too clever.

There are two completely different meanings to the term \'bootstrap\' depending on the application. There is the linear analog electronic use which generally means a feedback configuration that adds an input to an amplified version of itself. Then there is computer engineering term which refers to the process at startup where the CPU defaults to a fixed location in program memory and starts executing the code there that configures and starts the machine. I\'ve seen the term applied to power supplies that is more like the computer engineering use. Turn on provides enough trickle power to a small power supply supervisory circuit that brings the rest of supply up to full power in a systematic way.

 

[John Larkin]

On Thu, 13 Jul 2023 14:04:09 -0400, bitrex <user@example.net> wrote:

What\'s the behavior of a simple regulator like the one in Fig 10, on
start-up and shut-down?

https://www.infineon.com/dgdl/Infineon-Application_Note_Applications_for_Depletion_MOSFETs-AN-v01_00-EN.pdf?fileId=5546d4624cb7f111014cd63d1a197d94

Take a look at SRH05. It\'s a little potted 3-pin switcher that
tolerates up to 72 volts in. It\'s very well behaved.