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.
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
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.
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 ?
both pin connect to even or odd pins port . it will automaticlly adjust the current ?
plzz inlighten me on this confusion ...........
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.
No, there is no active current management, its related to internal
buss drop to insure logic noise margin specs.
What are you actually driving ?
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.
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
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...
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
For driving to ground Rled = ( Vdd or Vbatt - Vthled - Vol ) / Iled.
The port can handle the current, you could parallel two pins to improve
what do you thing if i use switch mode pump and run M8C at 5V ...
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.