VB923

Bruce Plecan nacelp at bright.net
Tue May 30 12:26:55 GMT 2000


That really helps thanks
Grumpy

> It may be worth having a look at the data for other devices in the VBxxx
> series, search for VB? to get a list. eg. VB024/025/026/027 show some
> application/test circuits, although they are slightly different devices
with
> a status flag output, the principles are similar.
> I think the connection for the VB923 should be fairly straight forward -
> connect coil -ve to HVc terminal, ground to GND and a control signal which
> is able to provide 4V at 10mA (minimum) to Vin.
>
> The device actively clamps excess voltage when the coil turns off, and
more
> importantly if a plug lead becomes disconnected, so no additional
protection
> should be required at the HVc terminal. It may be prudent to clamp the
input
> signal to ensure the Vin terminal does not see excess voltage. It's
unclear
> from the datasheet exactly what the value of Vin(max) is, but I would
think
> that a 5V1 zener between Vin and GND should keep it happy.
>
> The minimum pulse-width of the input signal will be determined by the
> minimum supply voltage to the coil and the coil characteristics
(resistance
> and inductance). The minimum input pulse width must ensure that the coil
> current reaches its design max. or current limit of the device when the
> battery voltage is at minimum. (maybe a bit of experiment required?). A
> pulse width that exceeds this requirement will push the device into
current
> limit (a safe condition provided sufficient heatsink is available) for the
> duration of the pulse which exceeds the onset of current limit.
> Hope this helps, if I'm stating the **** obvious then I apologise.
>
> Rich.
>
> > -----Original Message-----
> > From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> > Behalf Of steve ravet
> > Sent: 29 May 2000 19:57
> > To: diy_efi at diy-efi.org
> > Subject: Re: VB923
> >
> >
> > There's a data sheet on the ST WWW page, www.st.com, type vb923 into the
> > search box.  It sucks, though, there's no sample circuit.  Only 5
> > pages.  I can't find anything else.  sounds like it might be
> > interesting, though
> >
> > --steve
> >
>
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