anybody make variable duty cycle Hall Effect switches?

[Scott Carter]

Greetings guys and gals -

Several manufacturers (at least Infineon, Allegro, Melixis, Anachip;
probably several others) make low power duty cycled Hall Effect switches.
The low power flavor appears to be typically about 0.1% duty cycle, with
a sleep interval in the 50-200 ms range.

Does anybody know of a manufacturer of a similar part where the duty cycle
mode can be either externally adjusted (ideally), or at least turned on
and off by a pin?

I have an application where most of the time the low duty cycle is exactly
what I need for its low power consumption, but there are times (known to
the code) when the rotating element is rotating fast enough that the low
duty cycle misses some rotation pulses.

The obvious solution (and the one I expect to have to implement) is to use
two switches next to each other, one the low duty cycle variety, and the
other a high duty cycle which would usually be powered down. But the
geometry of where the sensor wants to be makes fitting two, even SOT23s,
suprisingly difficult. If some obscure manufacturer known to the
remarkably knowledgeable denizens of this group makes the similar thing in
e.g. a SOT23-5 with a control pin I'll be very happy (and buy a few hundred
thousand of them).

Thanks in advance for any help -

Scott

 

[Robert Baer]

Greetings guys and gals -

Several manufacturers (at least Infineon, Allegro, Melixis, Anachip;
probably several others) make low power duty cycled Hall Effect switches.
The low power flavor appears to be typically about 0.1% duty cycle, with
a sleep interval in the 50-200 ms range.

Does anybody know of a manufacturer of a similar part where the duty cycle
mode can be either externally adjusted (ideally), or at least turned on
and off by a pin?

I have an application where most of the time the low duty cycle is exactly
what I need for its low power consumption, but there are times (known to
the code) when the rotating element is rotating fast enough that the low
duty cycle misses some rotation pulses.

The obvious solution (and the one I expect to have to implement) is to use
two switches next to each other, one the low duty cycle variety, and the
other a high duty cycle which would usually be powered down. But the
geometry of where the sensor wants to be makes fitting two, even SOT23s,
suprisingly difficult. If some obscure manufacturer known to the
remarkably knowledgeable denizens of this group makes the similar thing in
e.g. a SOT23-5 with a control pin I'll be very happy (and buy a few hundred
thousand of them).

Thanks in advance for any help -

Scott

Why not use a *linear* hall detector andd add your *own* logic to it?
Allegro has them.

 

[Scott Carter]

Why not use a *linear* hall detector andd add your *own* logic to it?
Allegro has them.

Fear of the unknown aka laziness :}, BOM cost, power consumption of the
discrete implementation, fear of not getting the chopper stabilization
quite right...

But a valid point nonetheless.

Scott

 

[Robert Baer]

Fear of the unknown aka laziness :}, BOM cost, power consumption of the
discrete implementation, fear of not getting the chopper stabilization
quite right...

But a valid point nonetheless.

Scott

Power consumption is adjustable via programming on/off duty cycles.
The Hall effect transducer would eat the most power (when on).
Everything else can be low power logic and op-amps and presumably left
on.
With a 5V supply, CMOS has almos zero drain at low frequencies, and
there are a raft of opamps that have rather low power requirements.
Chopper stabilized? What the heck for?
However, if you insist on using something you do not need for the
implimentation, there are a goodly number of off the shelf chopper
stabilized opamps - and some may have reasonably low power requirements.