From: David Lesher (wb8foz@nrk.com)
Date: 04/05/00-09:21:47 PM Z
Unnamed Administration sources reported that Holland Guldberg said:
> Here is some more information about step up power supply design:
> http://www.powerdesigners.com/InfoWeb/resources/pe_html/ch07s3/ch07s3p1.htm
FWIW:
Here's the reply from National:
..........
Because of the step-up configuration of the design requirement,
the switching current will be exceeded even with the 5-amp LM2587
switcher. With the LM2587, the max. load current available is
only 1.66A or 0.14A less than specified. [I had asked for 1.8
amps...]
Parallel operation of the LM2577 option is also satisfactory.
I checked the max. load current available for the parallel
combination and it indicated >2A (using 2 LM2577's). I assumed
that max. input voltage is 14V (8V min. spec).
When connecting the regulators in parallel, each output regulator
must be connected to a current sharing resistor, approx. 0.1 ohms
(a small strip of PCB etch should suffice) to ensure the regulator
with higher output voltage will not carry the load all by itself.
A large capacitor, say 2000uF, should be used for filtering the
combined outputs.
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