PWM fan IC question

[1-3-2-4]

For the fan output it requires a resistor to the transistor in my case I will be using a BD135 the fan I'm using is 12V .60A is a 100 ohm resistor sufficient enough?

The IC I'm using is a MIC502

 

[audioguru]

The MIC502 datasheet shows a minimum transistor drive current of 10mA. The BD135 transistor datasheet recommends a base current that is 1/10th the collector current so your circuit probably will not work since the MIC502 does not produce an output current of 0.6A/10= 60mA.
Micrel says to keep the base resistor value as high as possible (they recommend 250 ohms for a high gain transistor with less load current than yours) to reduce heating in the MIC502 but your transistor has lower gain and higher load current so it needs a much lower resistor value.

 

[1-3-2-4]

How about using a 510 mosfet instead?

 

[audioguru]

The datasheet for the IRF510 shows that it turns on well with a gate voltage of at least 10V.
The datasheet for the MIC502 shows that its output is only 8.6V when its output current is 10mA (but might be higher with less current).
Then some IRF510 Mosfets MIGHT NOT WORK.

The datasheet for an IRL510 shows that it turns on well with a gate voltage of at least 5V so all of them will work.

 

[1-3-2-4]

Hmm did not think of that. . With the bd531 will I need a heatsink on it? From whati understand I need a 200 ohm resistor on the base.

 

[audioguru]

I cannot find a datasheet for a BD531.

 

[1-3-2-4]

Sorry bd135, not at home right now

 

[audioguru]

Dyslexia?
With your load of 600mA then a BD135 needs a base current of 60mA but the datasheet for the MIC502 shows only 10mA.
Also IF the MIC502 can deliver 60mA without over-heating then we do not know its voltage drop. Then we cannot calculate the base resistor value.

 

[1-3-2-4]

Hmm I was told that it would not be a issue the calculations given to me on another site seems it's no problem

Rb = (12 - 0.6) / Ib
= 11.4 / 0.048
= 237.5 ohms

 

[audioguru]

Hmm I was told that it would not be a issue the calculations given to me on another site seems it's no problem

Rb = (12 - 0.6) / Ib
= 11.4 / 0.048
= 237.5 ohms

The other website is completely wrong. The datasheet for the MIC502 also has errors.

The datasheet for the BD135 shows that with a collector current of 500mA it saturates fairly when its base current is 50mA. Your collector current will be 600mA then the base current should be 60mA, not 48mA.

The datasheet for the MIC502 says that with a 12V supply, its OUT voltage is 3.2V, not 12V.
Graphs on the datasheet show that the OUT voltage is 3.8V, not 12V and not 3.2V.

The datasheet warns that if you allow the output current to be higher than 10mA then the IC gets hot. They show a graph that STOPS at 18mA, not 48mA.

If OUT is 3.2V and the base voltage of the transistor is 0.8V then the base resistor has 3.2V - 0.8V= 2.4V and its value for a current of 10mA is 2.4V/10mA= 240 ohms.

If OUT is 3.8V and the base voltage of the transistor is 0.8V then the base resistor has 3.8V - 0.8V= 3.0V and its value for a current of 10mA is 3.0V/10mA= 300 ohms.

But then the BD135 can have a collector current no more than 10mA x 10= 100mA. Maybe the MIC502 can produce an output current of 18mA then the collector current of the BD135 can have a collector current no more than 18mA x 10= 180mA.

Therefore your circuit probably will not work.