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Discussion Groups | LPC900 | LPC FLASH WRITE ON POWERFAIL


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Find help, specifications and source code for the LPC900. The LPC900 challenges Microchip and AVR based on the worlds most popular 8-bit architecture the 80C51. With a 2-clock core the LPC900 series is a high performance, very flexible and low cost 8-bit microcontroller family. Designers using or interested in these devices are encouraged to share their know-how and ask questions.

LPC FLASH WRITE ON POWERFAIL - Pragnesh Sheth - Apr 1 6:44:00 2005

Hello,
Is it posible to use brown out inrupt of lpc900 series device on power fail
to write data to internal flash.
Pragnesh


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Re: LPC FLASH WRITE ON POWERFAIL - philips_apps - Apr 1 16:04:00 2005


Hello Pragnesh,

this is a food and very important question and the answer is depending
on some of your system paramters.

1. You can generate an interrupt only for the higher Brown out trip
point which is between 2.7 and 2.4 Volt. There is a lower trip point
below 2.4V that offer reset only as event when it gets triggered. In
our tests the trip point for the higher BOD is very close to 2.5V when
the voltage is going down. You can write to the internal flash while
you are working within the specified voltages which are 2.4 - 3.6 V

2. How long you will be operating between the trip point and 2.4V,
that depends highly on your capacitors of the power supply. Check the
ramp down voltage of your supply and if you find out you have 10 ms
between 2.4 and 2.5V that gives you a few write cycles, however, if it
is only 1 ms that is too short.

3. You could actually use the comparator with the internal reference
voltage combined with an external resistor divider to find out earlier
about your power going away if you are using a voltage regulator.

4. It depends most about your power source. Running from a battery,
you will have hours or probably day / weeks below the trip point of
the interrupt and the actual power fail, running from a small voltage
regulator connected to AC and not much capacitors on board it might
only by a millisecond.

Hope this helps you to answer your question for your specific
environment.

Regards, Robert

--- In lpc900_users@lpc9..., "Pragnesh Sheth" <pragnesh@i...>
wrote:
> Hello,
> Is it posible to use brown out inrupt of lpc900 series device on
power fail
> to write data to internal flash.
> Pragnesh





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