I recently implemented a PWM based buck regulator in ATtiny13A (selected th=
is due to package size; the PIC i have on hand are 18F2455).
Features:

=A0 5-12V input, 4.15V max output with voltage foldback at 800mA,=A0 (yes y=
ou guessed it right, a lithium ion battery charger)
=A0"mains" detection, Battery under voltage protection, Charging indication=
 LED.

=A0 MIC3287 based white led driver driving a chain of 6 white LEDs (yes, so=
me sort of rechargeable torch)

Without any code optimisation , the 1K flash was 99% occupied.

-Mahesh


>________________________________
> From: David Duffy (AVD) <david@audiovisualdevices.com.au>
>To: Microcontroller discussion list - Public. <piclist@MIT.EDU>=20
>Sent: Thursday, 17 January 2013 2:30 PM
>Subject: Re: [PIC] Simple PWM Regulation
>=20
>On 17/01/2013 4:30 PM, IVP wrote:
>>> I was thinking the PWM should allow Vout to be the same as Vin
>>> (except for the MOSFET loss) when the PWM is at 100%
>> Fig18 is a buck-boost I use
>>
>> http://www.intusoft.com/onsemipdfs/an920-d.pdf
>>
>> Very handy when the input DC can be wide-ranging. For example
>> an SLA that could go from 11V+ to 14V and you need 12V out
>> or being able to grab just about any wallwart (particularly if a bridge
>> is added to the input to fix wrong polarity or AC)
>
>Hmmm... after checking out that MC34063 app note, I think the PIC + PWM=20
>design is the way to go.=A0 Only one high current component (cheap MOSFET)=
=20
>and I can also implement low voltage shut-down and other function very=20
>easily in firmware.
>
>I think the PIC method is also the safest bet for something I have to=20
>build a prototype of and ship overseas in the next couple of days.=A0 Once=
=20
>we get client feedback (overall project needs to be approved by someone=20
>else), we can go from there.
>David...
>
>--=20
>___________________________________________
>David Duffy=A0 =A0 =A0 =A0 Audio Visual Devices P/L
>Unit 8, 10 Hook St, Capalaba 4157 Australia
>Ph: +61 7 38235717=A0 =A0 =A0 Fax: +61 7 38234717
>Our Web Site: www.audiovisualdevices.com.au
>___________________________________________
>
>--=20
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>http://mailman.mit.edu/mailman/listinfo/piclist
>
>
>
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