Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

pic12F(LF)xxxx sink source pin current ...

Status
Not open for further replies.

voidptr

Member
hi, here my first noob questions :)

im currently using 2 pins of pic12F1840 to drive a circuit (one pin sourcing other sinking) compose of resistors and a coil.
every thing is fine when at Vdd = 5V
my circuit is not working at low Vdd = 2.5, not enough current flowing but it can be my fault bad choice of components tho.

i need to know if the current source sink max current for a pin (around 20mA i guess) is constant when Vdd go low, around like 2AA or 2.5V or on the complete space Vdd (2.3v to 5.5v) vs Clock diagram.

is it the same with the LF version ? Vdd (1.8v to 3.6v)
i think i will have sacrifice a pic to find that out ...
 
Last edited:
Look at the data sheet! It has a graph of output current verses supply voltage. hint: The current drops with supply voltage.
 
Look at the data sheet! It has a graph of output current verses supply voltage. hint: The current drops with supply voltage.

thanks ! but where ?
first my 12F1840 has no charts !
---------------------------
31.0 DC AND AC
CHARACTERISTICS GRAPHS
AND CHARTS
Graphs and charts are not available at this time.
----------------------------------

i got than info from
Absolute Maximum Ratings

Maximum output current sunk by any I/O pin.... 25 mA
Maximum output current sourced by any I/O pin ... 25 mA

and

VOL Output Low Voltage(4) I/O ports
max 0.6 V
IOL = 8mA, VDD = 5V
IOL = 6mA, VDD = 3.3V
IOL = 1.8mA, VDD = 1.8V

VOH Output High Voltage(4) I/O ports
min VDD - 0.7- V
IOH = 3.5mA, VDD = 5V
IOH = 3mA, VDD = 3.3V
IOH = 1mA, VDD = 1.8V


is this really that, max output at 3.3V is 6mA ?


i also took a peak one other pic12, but i didn't find that chart you said, there is not output io max current vs Vdd ...

i know im noob ! it is my first pic12 !
 
Last edited:
VOL Output Low Voltage(4) I/O ports
max 0.6 V
IOL = 8mA, VDD = 5V
IOL = 6mA, VDD = 3.3V
IOL = 1.8mA, VDD = 1.8V

VOH Output High Voltage(4) I/O ports
min VDD - 0.7- V
IOH = 3.5mA, VDD = 5V
IOH = 3mA, VDD = 3.3V
IOH = 1mA, VDD = 1.8V

This is not really the max current.
The part pulls low best so lets talk about that.
Supply = 5V
The output is low.
The load is from supply to pin.
The part will pull low to 0.6V from ground and supply 8mA. At 4mA the pin is at 0.3V. At 16mA it will be at 1.2V (approx.) The pull down looks like 75 ohms (at 5V supply).

At 1.8V supply the pull down will look like a 750 ohm resistor.
 
noob's tests ...

last week i got some time and i was still in need for some answer
i then tried to put on some tests myself ...
because a don't own a nice variable power supply, i just did some spot tests value ...
so for a PIC F version i was able to draw from an io pin at least 15mA on the complete
Vdd valid space ... of course Vpin change with Vdd but the output transistor seems to
be able to constantly source current ...
there's also the max current you can pass throught the pic, see spec for the formula, but in my case i only use 1 pin so, it doesn't matter ...

:)
 
Last edited:
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top