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Domestic half bridge or full brige ICs?

J

Joerg

Jan 1, 1970
0
Hello All,

What would be the half bridge or full bridge du jour these days? I mean
a cheap one, under a Dollar. Ye olde LM18293, one of my old favorites,
seems to have gone to lalaland along with a lot of others.

There are plenty of suitable big load driver chips from Japan but isn't
there something domestic? Ideally one that can be driven from 3V.

Regards, Joerg
 
W

Wouter van Ooijen

Jan 1, 1970
0
What would be the half bridge or full bridge du jour these days?

which current?


Wouter van Ooijen

-- ------------------------------------
http://www.voti.nl
Webshop for PICs and other electronics
http://www.voti.nl/hvu
Teacher electronics and informatics
 
T

Tilmann Reh

Jan 1, 1970
0
Joerg said:
What would be the half bridge or full bridge du jour these days? I mean
a cheap one, under a Dollar. Ye olde LM18293, one of my old favorites,
seems to have gone to lalaland along with a lot of others.

There are plenty of suitable big load driver chips from Japan but isn't
there something domestic? Ideally one that can be driven from 3V.

http://www.allegromicro.com are worth a look.
 
J

Joerg

Jan 1, 1970
0
Hello Tilmann,

Thanks. I had checked these out but got a sticker shock. Typically in
the several-Dollar class, too much for most designs. Maybe that's
because most of theirs contain PWM circuits and other stuff but that is
usually not needed if you drive it from a micro controller or other
circuitry.

Regards, Joerg
 
J

Joerg

Jan 1, 1970
0
Hello Wouter,
which current?

Around 1A and they don't have to stand more than 20V. Some used to
contain protection against spikes from an inductive load but that can
also be done outside the chip.

I am gradually finding myself migrating towards the good old ways of
doing bridges. Some mainstream chips disappear, then you try FETs but as
supply voltages are going ever lower that doesn't work or it becomes
expensive. Last but not least there is that old standby, the plain
vanilla bipolar transistor.

Regards, Joerg
 
W

Wouter van Ooijen

Jan 1, 1970
0
Around 1A and they don't have to stand more than 20V.

I don't think you will find something cheap in that reagion. There are
lots of cheap chips designed to handle small motors like in CDs, VCRs
etc, typically <500mA. There are also the more expensive chips
deisgned to handle more A. I am considering the MC33887. Nice chip,
but pricy.


Wouter van Ooijen

-- ------------------------------------
http://www.voti.nl
Webshop for PICs and other electronics
http://www.voti.nl/hvu
Teacher electronics and informatics
 
F

Frank Bemelman

Jan 1, 1970
0
Joerg said:
Hello Wouter,


Around 1A and they don't have to stand more than 20V. Some used to
contain protection against spikes from an inductive load but that can
also be done outside the chip.

I am gradually finding myself migrating towards the good old ways of
doing bridges. Some mainstream chips disappear, then you try FETs but as
supply voltages are going ever lower that doesn't work or it becomes
expensive. Last but not least there is that old standby, the plain
vanilla bipolar transistor.

Did you look at BTL audio amplifiers? Philips has a lot of these.
 
J

Joerg

Jan 1, 1970
0
Hello Frank,
Did you look at BTL audio amplifiers? Philips has a lot of these.

I did look at audio amps but they are too expensive. Philips is a
different story. Just take the TDA8512 as an example. Their web site is
slow, tends to wait for their stock price quite often. I mean, who
cares. Then I could not find a budget price (grayed out). Just great. If
they don't straighten that stuff out, whatever is left from my design-in
share for them is going to become even less. I wonder when they'll
understand that.

What I am really looking for is a replacement for the LM18293 and its
larger siblings. These were wonderful parts and cheap.

Regards, Joerg
 
F

Frank Bemelman

Jan 1, 1970
0
Joerg said:
Hello Frank,


I did look at audio amps but they are too expensive. Philips is a
different story. Just take the TDA8512 as an example. Their web site is
slow, tends to wait for their stock price quite often. I mean, who
cares. Then I could not find a budget price (grayed out). Just great. If
they don't straighten that stuff out, whatever is left from my design-in
share for them is going to become even less. I wonder when they'll
understand that.

That is true, without any indicative prices shown... yuk.
What I am really looking for is a replacement for the LM18293 and its
larger siblings. These were wonderful parts and cheap.

Still I wonder how well these audio amplifiers would suit for driving
small motors. The wattage isn't really a good parameter to filter on.
Assuming that these amplifiers outputs can go pretty much rail-to-rail,
the dissipation would be low anyway, for a motor application. To know
what the maximum current is, is more interesting.

Next week I plan to make a few small amplifiers for a gadget, trying a
couple of these smaller BTL chips. I'm still waiting for some parts.
I'll experiment a bit, what maximum current is that can be drawn from
them before they pop.

And of cource, you can always make a discrete bridge. But I am sure
you will find something excellent ;)
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Frank Bemelman <f.bemelmanq@xs4all
..invalid.nl> wrote (in said:
Assuming that these amplifiers outputs can go pretty much rail-to-rail,
the dissipation would be low anyway, for a motor application. To know
what the maximum current is, is more interesting.

The maximum current is usually quoted on the data sheet. Many such
devices have internal current-limiting, of course, i.e. 'short-circuit
protection'.
 
F

Frank Bemelman

Jan 1, 1970
0
John Woodgate said:
I read in sci.electronics.design that Frank Bemelman <f.bemelmanq@xs4all


The maximum current is usually quoted on the data sheet. Many such
devices have internal current-limiting, of course, i.e. 'short-circuit
protection'.

Good point ;) I'm looking at the TDA7052A datasheet now, repetitive output
current is 1.25A, non-repetitive 1.5A, 8 pin dip. Short-circuit proof and
thermally protected. $1.40 at www.arrow.com Seems usuable for a small
motor,
but way over Joerg's budget of $1.

I don't know how 'repetitive' translates into 'continious'. One would
still like to know how well it goes 'rail-to-rail' and how much power
is dissipated. A test on the bench would quickly reveal that, if I
actually had the part.

The datasheet is more aimed at it's intended use, as an audio amplifier
in linear mode.
 
J

Joerg

Jan 1, 1970
0
Hello Frank,
Good point ;) I'm looking at the TDA7052A datasheet now, repetitive output
current is 1.25A, non-repetitive 1.5A, 8 pin dip. Short-circuit proof and
thermally protected. $1.40 at www.arrow.com Seems usuable for a small
motor,
but way over Joerg's budget of $1.

That price isn't so bad. But if you plan to switch something big after
peeking at the abs max ratings, don't hold your breath. The THD curves
above 1W are not looking so encouraging. Often that indicates that the
final stage might be kind of wimpy for switching heavy loads.

BTW, I am going with bipolar transistors. Ah, the good old days. Mainly
because there aren't many reasonably priced FETs that can safely
operate with Vgs < 3V. Best of all, bipolar transistors are cheap and
ubiquitous.

Regards, Joerg
 
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