Lpc2000

Philips is recommending CAPFREE LDO-s (SA57000-33D and SA57017-18D) . Could
this sequencing problem the reason?
Is it possible to run LDO power supplies with no caps?
(TI, National etc. all recommend bypass caps, Philips does not)
j
----- Original Message ----- 
From: "tsvetanusunov" <tusunov@...>
To: <lpc2000@yahoogroups.com>
Sent: Thursday, February 26, 2004 12:09 PM
Subject: Re: [lpc2000] LPC2106 code run problems?


> >Random guess. Power supply sequencing and SCR latchup internal to the
> part.
>
> Bill,
>
> this is the exact source of the problem!
> adding 47uF capacitor to the +3.3V LM1117 removed the problem, it
> seems that for whatsoever reason on these boards +3.3V rises faster
> than +1.8V and this latch up LPC2106.
> On all our future boards we'll put 10uF to +1.8V and 47uF to +3.3V
> regulator thus will ensure some delay on +3.3V.
>
> this explains why these boards started to work when +3.3V vreg was
> working to +2.5V with insufficient Vin - in this case the output of
> +3.3V vreg rises slower and ensure the correct sequencing.
>
> Best regards
> Tsvetan
>
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>
> Yahoo! Groups Links
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