On Sat, 9 Sep 2000, Sean H. Breheny wrote:

That was a good idea with a second regulator. In fact I already have the
construction set  up like that, with one regulator for the CPU and
another one for the rest. It is fed from NiMh-cells, by the way.

But I did something very stupid, I don't know why, I connected the input
of regulator #2 to the output of #1. I don't understand why I did that, I
haven't been drinking or so, maybe I was just tired after a busy week ??

So, I will correct this and make another attempt !

Thank you for your ideas and encouragement

Regards

Attila - SM4RAN


> Hi Atilla,
>
> Are you sure you need to regulate the supply of the tda2822? I just took a
> quick look at its datasheet and it says that it accepts input voltages from
> 3 to 15v, so you might be able to feed the amp's supply from the input
> directly. What is the input supply voltage (before the regulator) and what
> is its source (battery, transformer-based power supply ,etc?) The TDA2822
> has a minimum of 24dB supply voltage rejection (at 100kHz), and the
> rejection goes up to 30 dB at 100Hz. So, as long as your input supply
> doesn't contain large amounts of noise, this should work.
>
> If your input supply is suspect, or you need to run the amp at a lower
> voltage, then why not use a separate regulator for the amp and for the
> microcontroller? (Reading your message more carefully, I now see that you
> need shutdown capability, so why not use a second regulator with shutdown
> ability?)
>
> Sean
>
>
>
> At 05:56 PM 9/9/00 +0200, you wrote:
> >Hi list!
> >
> >I'm using a TDA2822S from ST Microelectronics, supplied from a MAX604 5V
> >500 mA regulator with 220uF caps on both input and output. The input
> >current to the MAX is more than enough
> >
> >What happens is this: When turning the amp on there is a high current
> >transient, which causes a voltage drop, which causes the processor to
> >reset.
> >
> >Is there a simple way to solve this problem without replacing the voltage
> >regulator ?   This is a battery powered application so a low standby
> >current is necessary. Therefor I also need the shutdown facility of the
> >regulator.
> >
> >When I manage to get the application running, the amp behaves as it
> >should.
> >
> >Any ideas on how to make a 'soft start' with a TDA2822S ??
> >
> >
> >Regards
> >
> >
> >Attila Muhi  -  SM4RAN
> >
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