maximum current on an stk500

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Hello,

I'm planing a small circuit that will be plugged onto the stk500 via the expansion connector 0/1. Now I must know how many current my circut can consum when I'm using VTG as supply voltage.

Regards

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It surely would help to give a rough estimate. Are you looking for 10mA? 100mA? 1000mA?

The schematics of the STK500 are readily available. IIRC, there is a standard LM317 that is then adjusted to give VTG. Most of your answer will be the specs of the LM317. Much of the rest will depend on what you are powering the STK500 with.

With an appropriate "wall wart" of 500+mA, you should have no problems powering a few hundred mA--e.g., an LCD with backlight.

Since we all love our STK500s like a family member, it made me feel better to add a heat sink to the LM317 and '7805 on my "main" dev STK500.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Hello,
my application will consum around 350 mA, has already someone calculated the consumption of the parts that are mounted on the stk500 (without the target AVR)?

Regards

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Like, insignificant compared to 350mA. Put your current meter across the VTARGET jumper. The "system" part of the STK500 has its own regulator.

As I said, see the schematics. Look at the LM317 specs. Heat sink if you have a large voltage drop.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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I guess that depends on the uC chosen, and the number of LEDs lit up. One could calculate an estimated max current for the board, or stick an ammeter in series with its power supply and measure it .

I've always considered the STK500 a development platform, and not a power supply.

Much easier, especially at 350 mA, to have a separate power supply for your project, and tie the grounds together.

JC

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Quote:

I've always considered the STK500 a development platform, and not a power supply.

;) I find I rarely use the STK500 as a development platform--we will normally make a board for the prototypes, or butcher an existing app.

But I do use it as my primary ISP platform, and that includes often/usually powering the target through the ISP interface for ISP and development. It is VERY handy, IMO, to have a nice programmable power supply when doing different apps. Easy to step up and down to check brown-out levels, operation at low supply voltage, and the like. Sure, you could use a bench supply but then you have to connect it to the target board somehow--our apps often have the "normal" supply on a different board, and it is very handy to work with the AVR board itself. And there has to be provisions for ISP connection anyway. Very simple. [Now, danni doesn't need that ISP connection so his values will be different. ;) ]

A glance at the datasheet (doing OP's legwork) indicates 500mA or more for that regulator depending on the voltage drop. Cement on a heat sink and much more is possible.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.