[SOLVED] Powering up a fan (3 wire) using MOSFET LL110

[InNeedOfHelp]

Hey peoples, i need your help here trying to power up a fan using a FET transistor.

Fan has 3 wire . Red Black Yellow



This is the MOSFET im using.


and i also believe there is this component that my supervisor gave me but i can't find the details and the datasheet. i believe it is US 75 thermal sensor. something similiar to TC74 .

 

[hemnath]

Read about the mosfet. Best tutorial i found, read the pdf i have attached.

N-channel Enhancement Mosfet means, when u positive gate voltage, conduction starts from drain to source

Select the mosfet according to your design,
and read the datasheet of your mosfet ...
Connect red wire to Drain of mosfet, black wire to source of mosfet. When you apply gate voltage, conduction starts and drain to source, and the fan will starts rotating. Is this you need?

Best wishes.

 

[InNeedOfHelp]

Thank you very much.

 

[InNeedOfHelp]

So the yellow wire no need connect?

 

[hemnath]

you just need to run the fan right? .. yellow wire reports the RPM of the fan ..
leave it in your case. just connect red and black wires.

 

[InNeedOfHelp]

hi Hemnath,

i followed your instructions and successfully power up the fan ..
Now i got another new problem is that i must somehow press a button on the demo board 02-01630-1 and power up the fan using C programming codes.
Any advice on this situation.
Look forward to your reply asap .

thank you very much

 

[hemnath]

well its not a big problem.
This is the logic and you can use it.
IF (button_pressed)
then output_high(fan)
else
output_low(fan)

 

[InNeedOfHelp]

but what about the connection of the fan to the board, do i need to wire-wrapped anything?

 

[hemnath]

looking in your LL110 datasheet, it shows Vgs = 5V.
If your microcontroller output is +5v, then only it switches the mosfet compelety ON.
So i recommend you to use a npn transistor and mosfet to power up the fan.
connect output from uC pin to base of NPN transistor with a series resistor, and more than 5V(say about +6V) to collector, and emitter to gate of MOSFET.
output from uC pin switches the NPN transistor and which switches the gate voltage.

 

[InNeedOfHelp]

is there any ways to connect without using a NPN transistor as resource for this project only gave me ll110 only..

 

[InNeedOfHelp]

Hi Hemnath,

the datasheet of the fan says that the yellow wire is a sensor..
do you know what it meant by that?

 

[hemnath]

As replied in post #5, i mentioned about this. that is, tachometer output to indicate that the fan is running and the speed to the processor. in your case, i think you can leave that wire.

 

[InNeedOfHelp]

oh..
i managed to display some words in the LCD already .
can you teach me how to initialise the TC74?
before initialize the TC74 do we need to initialize the i2c ?

 

[hemnath]

ofcourse, first you must initialize the i2C before getting the data.

 

[InNeedOfHelp]

how to initialize it ?

#define		TC74_READ	   0x9B
#define		TC74_WRITE	   0x9A   

//////////////////////////////////////////////////////////////
void tc74_write(unsigned char reg,unsigned char val)
{
i2c_start(); 
i2c_write(TC74_WRITE);    
i2c_write(reg);  
i2c_write(val); 
i2c_stop(); 
}  
//////////////////////////////////////////////////////////////
void tc74_read(unsigned char reg,unsigned char *value)
{
i2c_start();
i2c_write(TC74_WRITE);
i2c_write(reg); 
i2c_repStart();
i2c_write(TC74_READ);
*value=i2c_read(0);  //ACK 
i2c_stop();   
}

is this correct?

 

[hemnath]

signed int8 TC74_read_temperature(void)
{
signed int8 retval;

i2c_start();
i2c_write(TC74_WRITE);
i2c_write(TC74_READ); 

i2c_start();   // Re-start
i2c_write(TC74_READ);
retval = i2c_read(0);
i2c_stop();
return(retval);
} 

void main()
{
signed int8 temp;
while(1)
  {
   temp = TC74_read_temperature();
   printf("Temperature (C) = %d\n\r", temp);
   delay_ms(1000);
  }
}

 

[InNeedOfHelp]

:hemnath , could you help me write out the whole program ?

 

[hemnath]

what else you want to do in your project? i have posted in #16. did you tried it? Does it displays the ADC value in LCD?

 

[InNeedOfHelp]

the post in #16 has some errors..

 

[hemnath]

what error it shows?