Lower power TL494, MC33063 etc.?

[Joerg]

Guess we all have used those staples. Those kinds are about the only
cheap PWM chips when it comes to voltages above logic levels. However,
unfortunately they were designed before the energy crisis and need lots
of quiescent current. Is there anything available or maybe in design
with the following specs:

a. buck, or multi-mode
b. internal switch
c. <<1mA quiescent
d. 7-40V input
e. ahem, as usual: <40c a pop in qties

I found tons of suitable devices but they all failed requirement "e",
big time.

 

[legg]

Guess we all have used those staples. Those kinds are about the only
cheap PWM chips when it comes to voltages above logic levels. However,
unfortunately they were designed before the energy crisis and need lots
of quiescent current. Is there anything available or maybe in design
with the following specs:

a. buck, or multi-mode
b. internal switch
c. <<1mA quiescent
d. 7-40V input
e. ahem, as usual: <40c a pop in qties

I found tons of suitable devices but they all failed requirement "e",
big time.

Output current rating of the internal switch?

RL

 

[Joerg]

Output current rating of the internal switch?

That can be well under 100mA. It's for low power apps. Most of the
modern versions have surprising current capabilities. It's just that
they are priced way outside my usual wiggle room.

 

[legg]

That can be well under 100mA. It's for low power apps. Most of the
modern versions have surprising current capabilities. It's just that
they are priced way outside my usual wiggle room.

For a low power application jelly-bean, the last thing you'd
intentionally impose on a device is a high input voltage. In that case
you'd be looking for methods to cut the thing off completely, when not
needed and to bootstrap the control supply when it's running.

For < 1mA quiescent high voltage operating current, I don't see an
integrated buck regulator below 1.25. (lm5009)

LM2574, with a built-in shutdown capability, is 0.75. There are many
others like it.

At 100ma you could probably bodge something in any particular
application. Isn't that what the high-priced help is for?

If you could get by with buck-boost, using the positive input as the
ground connection, there are a host of commodity low power HV
integrated switchmode controllers that might be re-applied between 15
and 40V. The control inversion generally puts people off.

RL

 

[Joerg]

For a low power application jelly-bean, the last thing you'd
intentionally impose on a device is a high input voltage. In that case
you'd be looking for methods to cut the thing off completely, when not
needed and to bootstrap the control supply when it's running.

For < 1mA quiescent high voltage operating current, I don't see an
integrated buck regulator below 1.25. (lm5009)

LM2574, with a built-in shutdown capability, is 0.75. There are many
others like it.

At 100ma you could probably bodge something in any particular
application. Isn't that what the high-priced help is for?

Yep, it usually is. But most of the time that help leads to a discrete
solution. Looks like it does again this time. It's hard to beat 1.5c
transistors and 0.3c resistors, even when there are a lot of them.

If you could get by with buck-boost, using the positive input as the
ground connection, there are a host of commodity low power HV
integrated switchmode controllers that might be re-applied between 15
and 40V. The control inversion generally puts people off.

Oh, that wouldn't put me off at all. I love unorthodox solution, at
least in electronics ;-)