Re: Quick question - voltage regulators in parallel?

lain wrote:
Unfortunately if this works I'll be making a lot of them, so the
one-off solution won't work.. however after digging around the
data*** for this 7805 I see it says it's fine to go over 1A so long
as you provide adequate heatsinking... so I'll just slap a nice
heatsink on it & some thermal paste and hope for the best...

- Eric A.


Not gonna work for you. Your best approach is the
one redbelly gave in his response: the 7805 with
an MJ2955 PNP pass transistor - use a heat sink.

30 amps with a linear is possible with this method,
but it gets physically large - you'd need a BIG
heatsink and at least 4 pass transistors to be
safe.

You mentioned an automotive environment & big
caps. Forget massive capacitance. Someone mentioned
LC. I'll add this - use a TVS diode like a P6KE24
to ground with a voltage dropping resistor. The
general idea is like this:

+12 ---[L]---+----[1R]---+---[V/R]---[Load]---+
| | |
[C] [TVS] |
| | |
Gnd ---------+-----------+--------------------+

The LC acts to limit transients. The 1 ohm 25W power resistor
will drop 2 volts taking a little heat away from the regulator
under normal conditions. If a transient gets past the LC and
the TVS conducts, the power resistor will drop the voltage
and dissipate power so that the regulator & the TVS are
protected.

Ed
.

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