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Driving LED's | Cypress Semiconductor

Driving LED's

Summary: 5 Replies, Latest post by sjb69 on 01 Feb 2010 07:56 AM PST
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sjb69's picture
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6 posts

Hello,

Can you tell me the best way to drive four high current LED's from this board? I see there are four high current sinks (25 mA) (HC DO1, DO2, DO13, and DO 14), but can the on-board 3.3V regulator take the load?

Thanks, Steve

sjb69's picture
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6 posts

Hi Steve,

May I know which kit you are talking about.

Best regards,

Sachin

sjb69's picture
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6 posts
Originally posted by: sjb69

Hello,

Can you tell me the best way to drive four high current LED's from this board? I see there are four high current sinks (25 mA) (HC DO1, DO2, DO13, and DO 14), but can the on-board 3.3V regulator take the load?

Thanks, Steve

The Kit that all FIRST Teams are using is:

CY8CKIT-003 PSoC3 FirstTouchtm Kit

I'd also like to know this answer. Plus the following:

How many mA's on the non High Current DO's?

How many mA's total can we draw/sink?

sjb69's picture
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6 posts

Yes, it is the CY8CKIT-003 PSoC3 FirstTouch Kit

I checked the regulator part number, it is rated for 330 mA. Not sure how much your board draws, hopefully there is 150 mA head room at least. Bigger problem is the 3.3V supply. Blue, white, and high brightness green LED's take 3.5V usually to turn on, so that limits the colors we can use.

Steve

sjb69's picture
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6 posts

Steve,

In my opinion, the best way to drive high brightness LEDs is to use external driver (Transistor or FET) and use a higher Collector / Drain voltage.

mreffler,

For GPIOs, the sink/source current is 8mA/4mA. For SIOS, the sink/source current is 25mA/4mA

Each quadrant of the device has a VDDIO pin that provides the supply to the GPIOs in that quadrant. The total current that can be sunk / sourced is 100mA per quadrant.

sjb69's picture
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6 posts

Okay, that confirms my design direction. I'll have to check the schematic, hopefully I can get the 5v supply from the USB port down through the 28 pin header. I do not want to use batteries and the rules prohibit any supply other than the USB port.

Steve

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