Current Delivered by GPIO pin at 3.3 v

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DeAa_335316
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 I want know how much current delivered by GPIO pin ,when M8C runing at 3.2 v ?

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ETRO_SSN583
Level 9
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Look at the data sheet for the part you have choosen, there is

   

a source (P channel output transistor) and a sink (N channel

   

output transistor) spec for current delivered at a specific voltage.

   

In the electrical specifications section of datasheet.

   

 

   

Some data sheets also have curves of Iol and Ioh vs Vol and Voh.

   

 

   

Regards, Dana.

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DeAa_335316
Level 4
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 they mention Maximum Port pin current =50mA 

   

they did not mention the voltage level 

   

i want to know at 3.2 V level

   

what is the current deliver at strong mode , High Z , High Z analog , Pull up , Pull Down .

   

I am using CY8C28445-24PVXI 

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ETRO_SSN583
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The max port current is the limitation for all pins total

   

current allowed in the port.

   

 

   

You use the term source current, so that would be current sourced from Vdd

   

thru the P channel output transistor in the port driver.

   

 

   

   

 

   

 

   

   

 

   

 

   

Regards, Dana.

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Anonymous
Not applicable

 HI Dana thanks 

   

one silly question -

   

total current of port pin is 80mA and port are divided into two parts even and odd pins .

   

that means (80/2 ) 40mA for both even and odd ..

   

if we are using all 8 pins of port ...that means each pin deliver 10mA current .

   

Suppose if i want to use only two pins of port. and my requirement is 30mA current for each pin .

   

can i connect one pin to even port pins and other pin to odd port pins ?

   

or

   

both pin connect to even or odd pins port . it will automaticlly adjust the current ?

   

 

   

plzz inlighten me on this confusion ...........

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Bob_Marlowe
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I am afraid you take the test-conditions as absolute ratings. Only the second row of dana's last post shows what you want to know: IOH = min 10mA under the given conditions.

   

 

   

Bob

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ETRO_SSN583
Level 9
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No, there is no active current management, its related to internal

   

buss drop to insure logic noise margin specs.

   

 

   

What are you actually driving ?

   

 

   

Regards, Dana.

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DeAa_335316
Level 4
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 i want to connect two LED in parallel...

   

Today i tested Red , blue and green LED with 3v coin cell battery .

   

Red LED is taking = 20.1mA

   

Blue is taking =1.64mA

   

Green is taking = 2.55mA 

   

if i connect two Red LED in parallel .it need 40mA total current . 

   

if port not able to deliver such amount of current then voltage across the led will drop. then brightness of led will decrease.

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Bob_Marlowe
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Probably the first to give up is your coin-cell. The cr2032 has a capacity of ~200mAh which would result in 5hrs of your 2 red LEDs.

   

The first LED that will shut down is the blue one, because forward voltage for blue LEDs is ~2.9V

   

Forward voltages

   

Red   1.6V

   

Green 2.1V

   

Blue 2.9V

   

 

   

Working resistor is (UBatt - ULED) / ILED

   

Red: (3.3 - 1.6) / 20mA = 85 Ohm. Regarding cell capacity I would suggest to reduce current to 5mA (using a low-current LED) and an R of 330 Ohms.

   

 

   

Calculate for blue LED for yourself...

   

 

   

Bob

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ETRO_SSN583
Level 9
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I assume you dont actually mean two LEDs pin to pin parallel

   

as they will not current share properly due to Vth differences.

   

 

   

You can drive LEDs to ground or to Vdd, the former preferred because

   

the Nchannel has better switch characteristics =

   

 

   

   

 

   

The equation for Rled = ( Voh - Vled ) / Iled where Voh is estimated

   

Vbatt - Vdspchannel, latter from spec in DC characteristics. This for driving

   

to Vdd.

   

 

   

For driving to ground Rled = ( Vdd or Vbatt - Vthled - Vol ) / Iled.

   

 

   

The port can handle the current, you could parallel two pins to improve

   

Vol.

   

 

   

Regards, Dana.

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DeAa_335316
Level 4
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 what do you thing if i use switch mode pump and run M8C at 5V ... 

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ETRO_SSN583
Level 9
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The SMP is not capable of supplying the LED current you

   

need, so you would drive LEDs to ground, and use an alternate

   

supply/regulator to supply LED current. In addition you have to

   

insure the pin voltage when led off does not violate the allowable

   

voltage relative to Vdd on PSOC.

   

 

   

Regards, Dana.

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