[OT] Any nice IC to directly drive at least 4 relays?

[Mario]

Hello,
I have to drive 4 relays, the 12V coils absorb about 200mA but I would
like to be able to supply some more juice in case I changed relays later.

Is there a nice, ubiquitous, IC that I don't know yet, that will do the
job and, even better, has 3.3V inputs (preferably direct, parallel, but I
would consider also e.g. I2S) to command the relays, and integrated
flyback protection diodes? The relays are all low-side and I can't change
or rewire that.

An 8 output IC or versions that can sink directly even 3-5A would be
interesting to know too.

Thanks for sharing your knowledge.

Cheers,
Mario

[Sean Breheny]

Hi Mario,

When you say that the relays are low-side, do you mean that one end of the
coil is grounded?

If the relay coils can be connected between power and the switching device,
then the usual solution is the ULQ/ULN series of darlington arrays:

http://www.ti.com/lit/ds/symlink/ulq2003a.pdf

There may be a PNP version of this which would work with coils which have
one end grounded but I am not sure and don't have time right now to search
for it.

Sean

Post by Mario
Hello,
I have to drive 4 relays, the 12V coils absorb about 200mA but I would
like to be able to supply some more juice in case I changed relays later.
Is there a nice, ubiquitous, IC that I don't know yet, that will do the
job and, even better, has 3.3V inputs (preferably direct, parallel, but I
would consider also e.g. I2S) to command the relays, and integrated
flyback protection diodes? The relays are all low-side and I can't change
or rewire that.
An 8 output IC or versions that can sink directly even 3-5A would be
interesting to know too.
Thanks for sharing your knowledge.
Cheers,
Mario
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[Mario]

Post by Sean Breheny
Hi Mario,
When you say that the relays are low-side, do you mean that one end of the
coil is grounded?

Hi Sean,
with driving them low-side I mean that the +12V to one end of the coil is
fixed, to activate the relay I can only ground (and sink current) from the
other wire, which I have access to.

Post by Sean Breheny
If the relay coils can be connected between power and the switching device,
http://www.ti.com/lit/ds/symlink/ulq2003a.pdf

Yes I knew the 200X but for some reasons I was convinced that it sourced
current, not that it sinked it.

Post by Sean Breheny
There may be a PNP version of this which would work with coils which have
one end grounded but I am not sure and don't have time right now to search
for it.

Thank you anyway, I knew the 200X but I was convinced that it did the opposite,
i.e. that it sourced current, not sinked it. I even have some in a drawer, and
I never used them.

Anyhow, even if that info didn't help me (and it did), there are many other
people that read and any bit of information that is shared or even just
reminded here is always useful. Thanks.

Cheers,
Mario

Post by Sean Breheny
Sean

Post by Mario
Hello,
I have to drive 4 relays, the 12V coils absorb about 200mA but I would
like to be able to supply some more juice in case I changed relays later.
Is there a nice, ubiquitous, IC that I don't know yet, that will do the
job and, even better, has 3.3V inputs (preferably direct, parallel, but I
would consider also e.g. I2S) to command the relays, and integrated
flyback protection diodes? The relays are all low-side and I can't change
or rewire that.
An 8 output IC or versions that can sink directly even 3-5A would be
interesting to know too.
Thanks for sharing your knowledge.
Cheers,
Mario
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[Manu Abraham]

TPIC2701: 7 channels 0.5A, 60Vmax
Similar and pin compatible to ULN200x
https://www.digikey.in/product-detail/en/texas-instruments/TPIC2701N/296-10865-5-ND/382343

Cheers,
Manu

Post by Mario
Hello,
I have to drive 4 relays, the 12V coils absorb about 200mA but I would
like to be able to supply some more juice in case I changed relays later.
Is there a nice, ubiquitous, IC that I don't know yet, that will do the
job and, even better, has 3.3V inputs (preferably direct, parallel, but I
would consider also e.g. I2S) to command the relays, and integrated
flyback protection diodes? The relays are all low-side and I can't change
or rewire that.
An 8 output IC or versions that can sink directly even 3-5A would be
interesting to know too.
Thanks for sharing your knowledge.
Cheers,
Mario
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[Mario]

Thanks, will look at it.

Greets,
Mario

Post by Manu Abraham
TPIC2701: 7 channels 0.5A, 60Vmax
Similar and pin compatible to ULN200x
https://www.digikey.in/product-detail/en/texas-instruments/TPIC2701N/2
96-10865-5-ND/382343
Cheers,
Manu

Post by Mario
Hello,
I have to drive 4 relays, the 12V coils absorb about 200mA but I would
like to be able to supply some more juice in case I changed relays later.
Is there a nice, ubiquitous, IC that I don't know yet, that will do the
job and, even better, has 3.3V inputs (preferably direct, parallel, but I
would consider also e.g. I2S) to command the relays, and integrated
flyback protection diodes? The relays are all low-side and I can't change
or rewire that.
An 8 output IC or versions that can sink directly even 3-5A would be
interesting to know too.
Thanks for sharing your knowledge.
Cheers,
Mario
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[Forrest Christian (List Account)]

I see others have already mentioned the ULN/ULQ series. There are lots of
options there, depending on your situation.

If you can tolerate a serial interface, the TPIC6B595 is pretty common.
There are other TPICs as well, I see at least one was mentioned...

However, most of those are low-side switching, if you meant that you need
to switch the positive rail, there are fewer options..... However, you said
'sink' so I think you probably meant the relays are tied to the positive
rail.

Just in case you do need a high side switch I've used a LMD18400 for this
type of thing in the past, it might be what you are looking for. Pricey
but worth it.

Post by Mario
Hello,
I have to drive 4 relays, the 12V coils absorb about 200mA but I would
like to be able to supply some more juice in case I changed relays later.
Is there a nice, ubiquitous, IC that I don't know yet, that will do the
job and, even better, has 3.3V inputs (preferably direct, parallel, but I
would consider also e.g. I2S) to command the relays, and integrated
flyback protection diodes? The relays are all low-side and I can't change
or rewire that.
An 8 output IC or versions that can sink directly even 3-5A would be
interesting to know too.
Thanks for sharing your knowledge.
Cheers,
Mario
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

--
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: [phone] | Address: 3577 Countryside Road, Helena, MT 59602
***@imach.com | http://www.packetflux.com
<http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux>
<http://twitter.com/@packetflux>

[Mario]

Post by Forrest Christian (List Account)
I see others have already mentioned the ULN/ULQ series. There are lots of
options there, depending on your situation.
If you can tolerate a serial interface, the TPIC6B595 is pretty common.
There are other TPICs as well, I see at least one was mentioned...
However, most of those are low-side switching, if you meant that you need
to switch the positive rail, there are fewer options..... However, you said
'sink' so I think you probably meant the relays are tied to the positive
rail.
Just in case you do need a high side switch I've used a LMD18400 for this
type of thing in the past, it might be what you are looking for. Pricey
but worth it.

Thanks for the informations, I will take a look at these chips.

With kind regards,
Mario

Post by Forrest Christian (List Account)

Post by Mario
Hello,
I have to drive 4 relays, the 12V coils absorb about 200mA but I would
like to be able to supply some more juice in case I changed relays later.
Is there a nice, ubiquitous, IC that I don't know yet, that will do the
job and, even better, has 3.3V inputs (preferably direct, parallel, but I
would consider also e.g. I2S) to command the relays, and integrated
flyback protection diodes? The relays are all low-side and I can't change
or rewire that.
An 8 output IC or versions that can sink directly even 3-5A would be
interesting to know too.
Thanks for sharing your knowledge.
Cheers,
Mario
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

--
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: [phone] | Address: 3577 Countryside Road, Helena, MT 59602
<http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux>
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[s***@interlog.com]

Post by Mario
Hello,
I have to drive 4 relays, the 12V coils absorb about 200mA but I would
like to be able to supply some more juice in case I changed relays later.
Is there a nice, ubiquitous, IC that I don't know yet, that will do the
job and, even better, has 3.3V inputs (preferably direct, parallel, but I
would consider also e.g. I2S) to command the relays, and integrated
flyback protection diodes? The relays are all low-side and I can't change
or rewire that.
An 8 output IC or versions that can sink directly even 3-5A would be
interesting to know too.
Thanks for sharing your knowledge.
Cheers,
Mario

Hi, Mario:-

For a 200mA+ 12V low side driver, I would be tempted to use AO9926B
(dual N-channel MOSFET) and BAT54 or BAV99 dual diodes.

4 parts to drive 4 relays.

Common parts like ULN2003 contain the diodes and are cheap, but are
marginal at 200mA with multiple outputs on. Being Darlingtons they
drop a lot of voltage
and thus get hot.

-- Spehro Pefhany

[Van Horn, David]

The diode across the coil method isn't the best either, if you care how quickly the relay opens.
Slow opening can result in contact welding.

The best method is a Zener from Collector/Drain to ground. Set the Zener voltage a bit below the transistor VCE/VDS rating.
This speeds up the collapse of the current in the coil by as much as 3x.

[Spehro Pefhany]

Post by Van Horn, David
The diode across the coil method isn't the best either, if you care how quickly the relay opens.
Slow opening can result in contact welding.
The best method is a Zener from Collector/Drain to ground. Set the Zener voltage a bit below the transistor VCE/VDS rating.
This speeds up the collapse of the current in the coil by as much as 3x

Dave is right, this will help get rated life out of the relays. They are *not* rated with diodes directly across the coils. You may be able to use one TVS or Zener (total) and one diode per relay.

Spehro Pefhany

Post by Van Horn, David
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[Sean Breheny]

Do you guys have actual test data showing improved life with the zener or
tvs instead of a simple diode? Every relay I've seen which had an
integrated diode used a simple switching diode. Also, usually the current
required to keep the relay closed is only a tiny fraction of that required
to make it close so only a small portion of the coil current decay is
relevant to the actual speed at which the contacts open. On top of that,
usually relays are designed so that the magnetic circuit is broken before
the electrical circuit - and once the magnetic circuit starts to open there
is a positive feedback effect which causes the attractive force to drop
very rapidly. In sum, I would be very surprised if the type of diode made
much difference to the contact life, except for reed relays. I thought that
the usual reason for wanting the field to collapse faster was to make the
delay from open signal to actual open circuit shorter for system reasons.

Post by Van Horn, David
The diode across the coil method isn't the best either, if you care how

quickly the relay opens.

Post by Van Horn, David
Slow opening can result in contact welding.
The best method is a Zener from Collector/Drain to ground. Set the Zener

voltage a bit below the transistor VCE/VDS rating.

Post by Van Horn, David
This speeds up the collapse of the current in the coil by as much as 3x

Dave is right, this will help get rated life out of the relays. They are
*not* rated with diodes directly across the coils. You may be able to use
one TVS or Zener (total) and one diode per relay.

Spehro Pefhany

Post by Van Horn, David
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[s***@interlog.com]

Post by Sean Breheny
Do you guys have actual test data showing improved life with the zener or
tvs instead of a simple diode? Every relay I've seen which had an
integrated diode used a simple switching diode. Also, usually the current
required to keep the relay closed is only a tiny fraction of that required
to make it close so only a small portion of the coil current decay is
relevant to the actual speed at which the contacts open. On top of that,
usually relays are designed so that the magnetic circuit is broken before
the electrical circuit - and once the magnetic circuit starts to open there
is a positive feedback effect which causes the attractive force to drop
very rapidly. In sum, I would be very surprised if the type of diode made
much difference to the contact life, except for reed relays. I thought that
the usual reason for wanting the field to collapse faster was to make the
delay from open signal to actual open circuit shorter for system reasons.

The magnetic circuit breaks (and inductance drops rapidly) just before
the contacts open because there is compliance in the contacts, so the
force from
the field slows them down just at the very worst time.

You can read these app notes, for example, but there are otehrs.

http://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=13C3264_AppNote&DocType=CS&DocLang=EN

http://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=13C3311_AppNote&DocType=CS&DocLang=EN

"It is normal industry practice to test relays and subsequently establish
performance ratings without coil suppression"

Song Chuan says;

http://www.songchuan.com/en/Technical-Infomation.pdf

12. Relay Coil Transient Suppression
The use of a single diode in parallel with the coil for
transient suppression causes longer contact release time.
On power relays, longer release time may reduce relay
life. For longer contact life, use a zener and diode,
a capacitor and resistor, or only a resistor.


Using a zener or clamp to a higher voltage is, however, harder on the
transistor so examine the SOA specs.


You can also use a resistor + a diode per coil. Pick the resistor to
give you the desired voltage at the nominal coil current. Eg. 12V + a
diode drop above
the 12v supply voltage for a 200mA relay would be 12/0.2 = 60 ohms and the
transistor would see a peak of 24.7V or so, nominally.

--sp

Post by Sean Breheny

Post by Van Horn, David
The diode across the coil method isn't the best either, if you care how

quickly the relay opens.

Post by Van Horn, David
Slow opening can result in contact welding.
The best method is a Zener from Collector/Drain to ground. Set the Zener

voltage a bit below the transistor VCE/VDS rating.

Post by Van Horn, David
This speeds up the collapse of the current in the coil by as much as 3x

Dave is right, this will help get rated life out of the relays. They are
*not* rated with diodes directly across the coils. You may be able to use
one TVS or Zener (total) and one diode per relay.
Spehro Pefhany

Post by Van Horn, David
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[Van Horn, David]

I don't have my original reference handy, but experience across millions of relays confirmed this, less problems where we used Zener suppression than where we used the conventional diode suppression.
This was driving small AC motors for draperies.

[Harrison Cooper]

Chiming in late...

But I've grown fond of the OnSemi NUD series of devices to drive relays and solenoids. They have both single and duals.

[David Strumpf]

Any advice on Modulo 7 math efficient conversions? I have a table filled with 21 digits of base 7 digits and need to process in 64 bit integer math.

Thanks for any help.

[p***@roadrunner.com]

...also, what radix do you want the results in?

- - Bob Ammerman
RAm Systems

-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of
David Strumpf
Sent: Monday, December 18, 2017 5:56 PM
To: ***@mit.edu
Subject: [OT] Mod-7 efficient math

Any advice on Modulo 7 math efficient conversions? I have a table filled
with 21 digits of base 7 digits and need to process in 64 bit integer math.

Thanks for any help.

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change
your membership options at http://mailman.mit.edu/mailman/listinfo/piclist

[David Strumpf]

Thank you for asking these questions. Making me think and rethink. The table data is stored as Radix 8. But, now I need to think what do I really need the resulting format. I was thinking a 64 bit integer result (but I will revisit) and respond.

Thanks!
<div>
Sent from AOL Mobile Mail


-----Original Message-----
From: picram <***@roadrunner.com>
To: 'Microcontroller discussion list - Public.' <***@mit.edu>
Sent: Mon, Dec 18, 2017 05:33 PM
Subject: RE: [OT] Mod-7 efficient math


...also, what radix do you want the results in?

- - Bob Ammerman
RAm Systems

-----Original Message-----
From: piclist-<a href="mailto:***@mit.edu">***@mit.edu</a> [<a href="mailto:piclist-***@mit.edu?">mailto:piclist-***@mit.edu</a>] On Behalf Of
David Strumpf
Sent: Monday, December 18, 2017 5:56 PM
To: <a href="mailto:***@mit.edu">***@mit.edu</a>
Subject: [OT] Mod-7 efficient math

Any advice on Modulo 7 math efficient conversions? I have a table filled
with 21 digits of base 7 digits and need to process in 64 bit integer math.

Thanks for any help.

--
<a href="http://www.piclist.com/techref/piclist" target="_blank">http://www.piclist.com/techref/piclist</a> PIC/SX FAQ & list archive View/change
your membership options at <a href="http://mailman.mit.edu/mailman/listinfo/piclist" target="_blank">http://mailman.mit.edu/mailman/listinfo/piclist</a>

[p***@roadrunner.com]

What mathematical functions do you need to perform?

- - Bob Ammerman
RAm Systems

-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of
David Strumpf
Sent: Monday, December 18, 2017 5:56 PM
To: ***@mit.edu
Subject: [OT] Mod-7 efficient math

Any advice on Modulo 7 math efficient conversions? I have a table filled
with 21 digits of base 7 digits and need to process in 64 bit integer math.

Thanks for any help.

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change
your membership options at http://mailman.mit.edu/mailman/listinfo/piclist

[Mario]

Post by Van Horn, David
The diode across the coil method isn't the best either, if you care
how quickly the relay opens.
Slow opening can result in contact welding.
The best method is a Zener from Collector/Drain to ground. Set the
Zener voltage a bit below the transistor VCE/VDS rating.
This speeds up the collapse of the current in the coil by as much as 3x.

Interesting. Going from relays to high impedance (12 ohm) fuel injectors,
a zener would make it close faster, I guess?

And, in this application, would it be better a 33V 5W zener or a 33V TVS?
I'm not sure how I would "size" the TVS, though, as they're usually rated
for peak power. I have some 33V SMB size ones rated 600W peak power but I
have no clue what continuous power they would reliably work on (well, an
injector closing is not "continuous" per sé, but I need to know if the TVS
diode can withstand that).

Is there an "experience rule" to quantify/translate peak TVS power to
equivalent Zener power?

Besides this, what are the difference between Zeners and TVS? AFAIK the
latter have a sharper knee and are generally much faster, but I'd like to
hear from the experts.

Cheers,
Mario

[Van Horn, David]

What's the rated voltage of your switching element?
The point is to let the voltage rise, but not high enough that it fails your transistor.
There are FETs with zeners from the drain to the gate for this reason, but that keeps the transistor on and keeps energy going into the load.




-----Original Message-----
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of Mario
Sent: Monday, December 18, 2017 11:47 PM
To: Microcontroller discussion list - Public.; Microcontroller discussion list - Public.
Subject: RE: [OT] Any nice IC to directly drive at least 4 relays?

Post by Van Horn, David
The diode across the coil method isn't the best either, if you care how
quickly the relay opens.
Slow opening can result in contact welding.
The best method is a Zener from Collector/Drain to ground. Set the
Zener voltage a bit below the transistor VCE/VDS rating.
This speeds up the collapse of the current in the coil by as much as 3x.

Interesting. Going from relays to high impedance (12 ohm) fuel injectors, a zener would make it close faster, I guess?

And, in this application, would it be better a 33V 5W zener or a 33V TVS?
I'm not sure how I would "size" the TVS, though, as they're usually rated for peak power. I have some 33V SMB size ones rated 600W peak power but I have no clue what continuous power they would reliably work on (well, an injector closing is not "continuous" per sé, but I need to know if the TVS diode can withstand that).

Is there an "experience rule" to quantify/translate peak TVS power to equivalent Zener power?

Besides this, what are the difference between Zeners and TVS? AFAIK the latter have a sharper knee and are generally much faster, but I'd like to hear from the experts.

Cheers,
Mario

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist

[Mario]

Post by Van Horn, David
What's the rated voltage of your switching element?

Currently I am using a 40V MOSFET and a 33V 5W Zener, and I was wondering
if a Transil would have a sharper knee, or better reliability.

Post by Van Horn, David
The point is to let the voltage rise, but not high enough that it fails your transistor.

Yes. The higher the voltage, the more the energy will be dissipated, but
it will happen out of the injector and thus the magnetic field will collapse
faster.. right?

Per contra, the zener will produce considerable heat, as it will be the one
that will dissipate the "injector closing" energy. That's why I think this
component is so critical.. and I would like to replace it with a Transil
(the hint is that as the high voltage flyback diode will work only for a
short part of the duty cycle (just at injector closing), a transil may be
possibily better because it seems more suited than a zener for "peak work",
while zeners are characterized for continuous work.. but I may have written
a lot of silly things, I don't know.. that's why I am asking).

Post by Van Horn, David
There are FETs with zeners from the drain to the gate for this reason,
but that keeps the transistor on and keeps energy going into the load.

Yes, an external component here is necessary. I just don't know if changing
the zener to a transil would be a good thing or not, and as both will work,
the difference may be noticed only after hundreds of hours.. hence it's a
job for the theory / knowledge / experience, which some of you certainly
have.

Cheers,
Mario

Post by Van Horn, David
-----Original Message-----
Sent: Monday, December 18, 2017 11:47 PM
To: Microcontroller discussion list - Public.; Microcontroller
discussion list - Public.
Subject: RE: [OT] Any nice IC to directly drive at least 4 relays?

Post by Van Horn, David
The diode across the coil method isn't the best either, if you care how
quickly the relay opens.
Slow opening can result in contact welding.
The best method is a Zener from Collector/Drain to ground. Set the
Zener voltage a bit below the transistor VCE/VDS rating.
This speeds up the collapse of the current in the coil by as much as 3x.

Interesting. Going from relays to high impedance (12 ohm) fuel
injectors, a zener would make it close faster, I guess?
And, in this application, would it be better a 33V 5W zener or a 33V TVS?
I'm not sure how I would "size" the TVS, though, as they're usually
rated for peak power. I have some 33V SMB size ones rated 600W peak
power but I have no clue what continuous power they would reliably
work on (well, an injector closing is not "continuous" per sé, but I
need to know if the TVS diode can withstand that).
Is there an "experience rule" to quantify/translate peak TVS power to equivalent Zener power?
Besides this, what are the difference between Zeners and TVS? AFAIK
the latter have a sharper knee and are generally much faster, but I'd
like to hear from the experts.
Cheers,
Mario
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

[RussellMc]

Post by Mario

Post by Van Horn, David
What's the rated voltage of your switching element?

Currently I am using a 40V MOSFET and a 33V 5W Zener, and I was wondering
if a Transil would have a sharper knee, or better reliability.

​A TL431 or similar driving a FET or even bipolar would ​give a very sharp
"knee" and minimal dissipation when not clamping.



Russell